KR100802696B1 - Lubricating oil composition for compressed natural gas engine - Google Patents

Abstract

An engine oil composition for a compressed natural gas engine is provided to protect an engine due to a good wear preventing function and a valve train and a piston due to a good oxidation preventing function and to extend the exchange period of engine oil. An engine oil composition for a compressed natural gas engine consists of base oil of 78~90wt.%, an anti-oxidation agent of 0.05~3wt.%, a purifying agent of 1~7wt.%, a viscosity index improving agent of 0.1~5.0wt.%, an anti-foaming agent of 0.0005~2wt.%, and a wear resistant agent of 0.5~5wt.%. The wear resistant agent is produced by mixing primary zinc-dialkyl dithiophosphate and secondary zinc-dialkyl dithiophosphate at the weight rate of 2:1. The base oil has a coefficient of kinematic viscosity of 3~10cSt at 100deg.C. Mineral oil and synthetic oil of a fixing agent with a viscosity index over 100 are individually used or mixed.

Description

Lubricating oil composition for Compressed natural gas engine

The present invention relates to an engine oil composition for a compressed natural gas engine, and more particularly, an engine oil composition prepared by generating a synergistic effect between components by containing a base oil, an antioxidant, a detergent, a viscosity index improver, an antiwear agent, and an antifoaming agent. The present invention relates to an engine oil composition for compressed natural gas engines that protects an engine with excellent anti-wear performance, protects a valve train and a piston because of excellent oxidation resistance, and extends an engine oil exchange cycle.

In order to improve the performance of engine oils, the SAE (Socie of Automotive Engineers), ASTM (formly the American Society for Testing and Materials) and API (American Petroleum Institute) Institutions are constantly working and various standards for engine oil have been set and improved.

In order to perform the crank mechanism, lubrication and cooling functions of various engine parts, the engine oil requires proper viscosity characteristics, extreme pressure, oxidative stability, and friction characteristics, which are lubricating performances under high loads. Eggplants must be properly formulated with base oils and additives.

In order to efficiently use energy and prevent global warming, regulations on automobile exhaust gas such as carbon dioxide are becoming more and more strict.In order to cope with such environmental regulations, engine oil used together with the change of engine structure to compressed natural gas (CNG) engine Development is underway for the purpose of improving fuel efficiency.

In addition, recently, the output per unit displacement of the engine is continuously increasing, and the air resistance coefficient of the vehicle shape is lowered to increase the thermal load on the engine oil.In general, when the temperature of the lubricating oil rises to 10 ° C, the oxidation rate is increased by 2 times. Shorten the life.

Thus, in the production of engine oil, antioxidants are usually mixed with base oil, and mercapto-based and phenol-based antioxidants are usually limited in antioxidant performance.

Accordingly, the present inventors have tried to solve the problems of the anti-oxidation and anti-wear performance of the engine oil.

As a result, amine-based antioxidants and primary zinc-dialkyldithiophosphates and secondary zinc-dialkyldithiophosphates are mixed in base oils in an optimum ratio and viscosity index improvers, blue tablets, dispersants, metal deactivators, and antifoaming agents. It was found that the engine oil composition prepared by synergistic effect of each component, including the back, has excellent anti-wear performance to protect the engine and excellent oxidation resistance to extend the engine oil replacement cycle.

Accordingly, an object of the present invention is to provide an engine oil composition for a compressed natural gas engine excellent in wear resistance and oxidation resistance.

In the present invention, the engine oil composition for a compressed natural gas engine comprising a base oil, an antioxidant, a detergent, a viscosity index improver, an antifoaming agent,

In the natural gas engine oil composition, an engine for compressed natural gas engines comprising 0.5 to 5 wt% of a primary zinc-dialkyldithiophosphate and a secondary zinc-dialkyldithiophosphate in a weight ratio of 2: 1. The oil composition is characterized.

The present invention will be described in more detail as follows.

Conventional engine oil is prepared by mixing a variety of additives in the base oil and the characteristics of the engine oil is affected by the additives a lot. The present invention is a combination of an anti-wear agent, antioxidant, and a cleaning agent to minimize the side effects caused by Ash (ash) and the engine oil composition that maintains the antioxidant and wear resistance.

The base oil used in the present invention is a generic term for lubricating oil used for lubrication of gear devices, and has a function of preventing rapid contact between tooth surfaces, reducing friction and wear, and preventing melting. The base oil has a kinematic viscosity in the range of 3 to 10 centistokes (cSt) at 100 ℃ and less than 3 centistokes (cSt) to increase the oil consumption by excessive evaporation under high temperature use conditions, more than 10 centistokes (cSt) Viscosity increases at low temperature, causing problems in low temperature startability. The base oil is used alone or mixed with a fixed mineral oil and synthetic oil, the content is used in the range of 78 ~ 90% by weight, when the content is less than 78% by weight of the additive is excessively increased, especially low temperature There is a problem that the viscosity increase in the severe, and when the amount exceeds 90% by weight of the additive is too small to exhibit the function as the engine oil.

The antioxidant used in the present invention has the property of preventing the oxidation of the engine oil. Specifically, one or a mixture of three or more selected from 3-hydroxydiphenylamine, phenyl-alpha-naphthylamine, etc. is used. . The antioxidant is used in the range of 0.05 to 3% by weight, the use of less than 0.05% by weight of the antioxidant performance is weakened, if the content exceeds 3% by weight such as competitive adsorption, metal corrosion occurs.

The detergent used in the present invention is used in the range of 1 to 7% by weight, and when used less than 1% by weight, the cleanliness is insignificant, and problems such as 7% by weight of competitive adsorption and ash generation occur. The detergent uses calcium sulfonate or magnesium sulfonate having an infectious value of 400 or more, and an amount of ash is increased due to an excessive amount of a detergent for exerting effective cleanliness when the infectious agent is less than 400.

The viscosity index improver used in the present invention has the characteristics of improving the viscosity index and increasing the fluidity at low temperature, and selected from ethylene-propylene copolymer, polyisoprene-polystyrene copolymer, hydrogenated styrene-isoprene, or the like. When two or more kinds of mixtures are used, the amount used is in the range of 0.1 to 5.0% by weight, and if less than 0.1% by weight, the low temperature fluidity deteriorates and the startability at low temperature is lowered. There arises a problem that the viscosity rises due to reduction and oxidation.

The defoaming agent used in the present invention is used in the range of 0.0005 to 2% by weight, and when used in an amount less than 0.005, there is a problem in that it is not possible to effectively suppress the generation of bubbles in the lubricating oil. A problem of precipitation in lubricating oil occurs, and one or two kinds of mixtures selected from silicone, polymethacrylate, and the like are used as the antifoaming agent.

The anti-wear agent used in the present invention is used in the range of 0.5 to 5% by weight and can be used at less than 0.5% by weight and can not exhibit effective wear resistance. Problems such as abrasion resistance is lowered, and the first zinc-dialkyldithiophosphate and the second zinc-dialkyldithiophosphate are mixed in a 2: 1 weight ratio to prevent initial abrasion when the weight ratio is less than 2: 1. The performance is deteriorated, and when the ratio exceeds 2: 1, there is a problem that wear resistance is degraded early due to sludge generation and deterioration due to competitive adsorption.

In the preparation method of the composition of the present invention, the base oil is first prepared, and then the additive having low activity is added, and the additive having low dosage is added at the same activity. In the case of this composition, the prepared base oil is added in the order of an antifoaming agent, a pour point lowering agent, a viscosity index improver, an antioxidant, and a cleaning agent. After the addition, the mixture is stirred using a stirrer at a temperature of 70 ° C. or higher, and the speed of the stirrer can be adjusted according to the size and design value of the stirrer. In the case of a small stirrer, the composition is prepared by stirring at 300 to 500 rpm in the case of a large stirrer at 100 to 400 rpm.

Hereinafter, the present invention will be described in more detail based on the following examples, but the present invention is not limited to the examples.

Example  1 and 2 and Comparative example  1 to 3

The components shown in Table 1 below were mixed under the condition that the temperature is 70 ℃, 400 rpm of the stirrer to prepare a composition. The physical properties of Examples 1 to 2 and Comparative Examples 1 to 3 were measured, and the results are shown in Table 2.

Test Example

1.Kinematic viscosity: measured by ASTM D 445 method.

2. Acid value: measured by ASTM D 664 method.

3. The total alkalinity was measured by ASTM D 2893 method.

4. Metal wear powder: measured by ASTM D 4951 method.

From the test results, it can be seen that the primary zinc-dialkyldithiophosphate, secondary zinc-dialkyldithiophosphate, and antioxidant were used in combination, and the change in kinematic viscosity compared to new oil was small, and the increase in the computational value was small. In addition, as a result of the analysis of metal wear, Examples 1 and 2 exhibited excellent performance in the valve wear at a significantly lower level. In particular, the wear of Example 2 shows a lower result than Example 1. In the case of Comparative Examples 1 to 3 using the conventional phenol-based antioxidant, the total acid value increased by more than 100%, and the total alkali value also dropped sharply, and it was impossible to use. It can be seen.

Therefore, when the engine oil is manufactured according to the present invention, the oxidation resistance is greatly improved, the service life is increased, and the valve seat wear resistance is excellent, and thus it can be applied to the lubricating oil used in the natural gas engine engine maintaining the optimal valve recession performance.

As described above, according to the present invention, the engine oil composition for a natural gas engine is greatly improved in oxidation resistance and excellent in wear resistance, and can be applied to engine oil used in natural gas engines such as automobiles.

Claims (7)

In the engine oil composition for compressed natural gas engine comprising a base oil, an antioxidant, a detergent, a viscosity index improver, an antifoaming agent, Compression, characterized in that the natural gas engine oil composition, containing 0.5 to 5% by weight of the first zinc-dialkyldithiophosphate and secondary zinc-dialkyldithiophosphate in a weight ratio of 2: 1 by weight Engine oil composition for natural gas engine. The method of claim 1, Base oil 78 ~ 90 wt%, antioxidant 0.05 ~ 3 wt%, detergent 1 ~ 7 wt%, viscosity index improver 0.1 ~ 5.0 wt%, defoamer 0.0005 ~ 2 wt% and primary zinc-dialkyldithiophosphate and secondary An engine oil composition for a compressed natural gas engine, wherein the zinc-dialkyldithiophosphate comprises 0.5 to 5% by weight of an antiwear agent mixed in a 2: 1 weight ratio. The method according to claim 1 or 2, The base oil has a kinematic viscosity of 3 ~ 10 cSt at 100 ℃, the engine oil composition for compressed natural gas engines, characterized in that using a fixed mineral oil and synthetic oil having a viscosity index of 100 or more alone or mixed. The method according to claim 1 or 2, The antioxidant is a compressed natural gas engine engine oil composition, characterized in that the mixture of one or two selected from 3-hydroxydiphenylamine, and phenyl-alpha-naphthylamine. The method according to claim 1 or 2, The cleaning agent is an engine oil composition for a compressed natural gas engine, characterized in that the total salt is calcium sulfonate of 400 or more, and one or two selected from magnesium. The method according to claim 1 or 2, The viscosity index improver is an engine oil composition for a compressed natural gas engine, characterized in that one or more selected from ethylene-propylene copolymer, polyisoprene-polystyrene copolymer, and hydrogenated styrene-isoprene. The method according to claim 1 or 2, The antifoaming agent is an engine oil composition for a compressed natural gas engine, characterized in that the silicone, and one or a mixture of two selected from polymethacrylate.