KR20120012126A - Manual Transmission Oil Composition Enhanced Low Temperature Transmission Performance - Google Patents

Abstract

PURPOSE: A manual transmission oil composition having improved low temperature speed change function is provided to offer the low viscosity at the low temperature for improving the durability of a manual transmission. CONSTITUTION: A manual transmission oil composition having improved low temperature speed change function contains 78-80wt% of polyalphaolefin synthetic base oil, 10-12wt% of polyalkyl methacrylate, and 8-12wt% of ash-free dispersing agent, extreme pressure additive, or their mixture. The manual transmission oil contains polyalphaolefin synthetic base oil. The base oil has the viscosity greater than 130. The number average molecular weight of the polyalkyl methacrylate is 300,000-400,000. The polyalkyl methacrylate contains 60-80wt% of C12-15 alkyl methacrylate and 20-40wt% of ethyl hexylmethacrylate.

Description

Manual Transmission Oil Composition Enhanced Low Temperature Transmission Performance

The present invention relates to a manual transmission oil containing a polyalphaolefin synthetic base oil and a viscosity modifier.

In general, the transmission is a device that is installed between the clutch and the propulsion shaft or the clutch and the reduction gear device to transmit the power of the engine to the driving wheel by changing the rotational force and speed to suit the driving state of the vehicle. The manual transmission changes the rotational speed and rotational force transmitted from the engine through gear shifting according to the clutch operation and driving conditions necessary to control the power and transmits it to the driving wheels to obtain the speed and torque required by the driver.

The vehicle manual transmission is equipped with a synchronizer transmission mechanism to facilitate the shift operation of the driver. The synchronizer shift mechanism is a mechanism for smooth shift operation by matching the speed of the clutch gear and the short term gear during shifting. In the synchronizer transmission mechanism, a gear forming sleeve is engaged in synchronism with the clutch gear and the short term by synchronizing the inclined surface of the synchronic mesh with the short term. At this time, if the oil viscosity rises excessively, the sensation of shifting is impeded by the friction at the time of contact, and the shifting feeling is lowered, and in particular, the shifting may not occur in the region where the outside air temperature is below -20 ~ -50 ℃.

In order to solve this problem, Korean Patent No. 298,035, Korean Patent No. 706,434, and Korean Patent Publication No. 2008-0109877 disclose a method of lowering the viscosity of an oil at a low temperature. The lower the viscosity of the manual transmission oil deteriorates the durability of the transmission, it may cause a problem that the rattle noise is increased.

Accordingly, the present invention, as a result of the efforts to solve the above problems, using a polyalkyl methacrylate having a number average molecular weight of 300,000 ~ 400,000 as a base oil synthetic base oil (PAO), a viscosity index improver (SAE 75W85) The present invention was completed by developing a manual transmission oil composition having a lower viscosity at a lower temperature than other manual transmission oils.

Accordingly, an object of the present invention is to provide a manual transmission oil composition having a high viscosity at high temperatures and having good durability and a rattling noise reduction performance required by a manual transmission, and having a low viscosity at low temperatures and having good transmission at low temperatures.

The present invention relates to a manual transmission base oil composition comprising a base oil and a viscosity index improver, wherein the base oil contains 78 to 80 wt% of a polyalphaolefin (PAO) synthetic oil, and a polyalkyl methacrylate having a number average molecular weight of 300,000 to 400,000 as a viscosity index improver. It is characterized by a manual transmission oil composition comprising a rate of 10 to 12% by weight and an additive of 8 to 12% by weight.

The manual transmission oil composition according to the present invention can improve the durability and rattle noise reduction and low temperature transmission of the manual transmission.

Hereinafter, the present invention will be described in more detail.

The base oil is a polyalphaolefin (PAO) synthetic base oil, and it contains a polyalkyl methacrylate having a number average molecular weight of 300,000 to 400,000 as a viscosity index improver to reduce durability and rattle noise. And other transmission oil compositions which can improve other performances (shear stability, frictional properties, thermal stability, and oxidation stability), and in particular, can reduce the flow resistance at low temperatures to improve low temperature shiftability.

Each of the compositions of the present invention will be described in more detail.

First of all, the base oil, which is one of the compositional compositions of the present invention, preferably uses a PAO synthetic base oil having an average kinematic viscosity of 100 ° C. of 3 to 8 cSt, a viscosity index of 130 or more, and a pour point of −60 ° C. or less. At this time, if the 100 ° C kinematic viscosity of the base oil is 3 cSt or less, there is a problem of increasing the oil usage due to excessive evaporation under high temperature conditions, and a viscosity increase at a low temperature is more severe than 8 cSt. It is preferable to use those having a kinematic viscosity in the above range. The amount thereof is preferably 78 to 80% by weight based on the total weight of the manual transmission oil composition.

Next, the viscosity index improver, which is one of the compositions of the present invention, increases the viscosity of the manual transmission oil, and serves to suppress the increase in viscosity at low temperatures, thereby increasing the viscosity index. The polyalkyl methacrylates preferably have at least four more preferably four to ten polymer chains. In addition, C ₁₂ It is preferable to include 60 to 80% by weight of C ₁₅ alkyl methacrylate and 20 to 40% by weight of 2-ethylhexyl methacrylate. It is preferable that the polyalkyl methacrylate has a kinematic viscosity of 100 ° C. or higher and 650 cSt or higher, and the amount of the polyalkyl methacrylate is preferably 10 to 12% by weight. And, if it exceeds 12% by weight, the viscosity at high temperature and low temperature is increased as well, causing a problem of lowering durability due to the viscosity decrease by shear during durability progression.

In addition, additives generally added to the manual transmission oil composition may be added. The additive is preferably added 8 to 12% by weight based on the total manual transmission oil composition. Specifically, the additive may be used alone or in combination with an anti-wear agent, a metal-based clean dispersant, a phosphate ester friction modifier, a bis succinimide type ashless dispersant, or an extreme pressure additive.

The antiwear agent is preferably zinc dithiophosphate, the metal clean dispersant is preferably calcium sulfonate, and polysulfide is preferably used as the extreme pressure additive.

Hereinafter, the present invention will be described in more detail with reference to Examples. However, the present invention is not limited by the following examples.

Example  1 to 3 and Comparative example  1 to 6: Manual Transmission Oil  Preparation of the composition

To prepare a manual transmission oil composition by stirring and mixing the composition shown in Table 1 under the conditions 60 ~ 80 ℃.

Classification (Unit: Weight%) Example Comparative example One 2 3 One 2 3 4 5 6 Synthetic base oils ^{1 )} 18.0 18.0 18.0 41.0 20.0 37.0 17.0 35.0 15.0 Synthetic base oils ^{2 )} 61.0 61.0 61.0 40.0 61.0 40.0 60.0 40.0 60.0 Viscosity index improver ^{3 )} 11.0 11.0 11.0 9.0 9.0 13.0 13.0 15.0 15.0 additive Zinc Dithio Phosphate 1.0 1.0 2.0 1.0 1.0 2.0 1.0 1.0 2.0 Calcium sulfonate 4.0 2.0 3.0 4.0 2.0 3.0 4.0 2.0 3.0 Phosphate Ester 2.0 4.0 2.0 2.0 4.0 2.0 2.0 4.0 2.0 Bis succinimide 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 Polysulfide 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 total 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 1) Chevron Philips PAO 4 (100 ℃ Kinematic Viscosity: 3.8cSt, Viscosity Index: 130, Pour Point: -69 ℃)
2) PAO 6 from Chevron Philips (100 ℃ Kinematic Viscosity: 5.9cSt, Viscosity Index: 135, Pour Point: -61 ℃)
3) Lubrizol (Anglamol) (number average molecular weight about 350,000)

Test Example : Viscosity (kinetic viscosity, -40 ° C) Low temperature viscosity ), Shear stability

Using the manual transmission oil composition prepared in Examples 1 to 3 and Comparative Examples 1 to 6 kinematic viscosity was tested according to ASTM D 445, low temperature viscosity according to ASTM D 2983.

Shear stability test was carried out for 48 hours according to CEC L-45-A99 (Viscosity Shear Stability of Transmission Lubricants (Taper Roller Bearing)) to measure the viscosity change in 100 ℃ by measuring the viscosity change as a ratio.

division Example Comparative example One 2 3 One 2 3 4 5 6 Kinematic viscosity (cSt) 100 ℃ 11.2 11.3 11.2 8.0 8.5 12.5 13.0 13.5 13.5 40 ℃ 51.1 49.3 49.5 39.7 42.1 59.3 61.2 68.2 69.2 Viscosity index 219 228 227 179 185 215 219 206 202 Low Temperature Viscosity (-40 ℃, cP) 11,000 10,000 10,000 10,000 10,500 15,000 18,500 28,000 30,000 Shear stability (%) 28 28 28 28 28 32 32 35 35

As shown in Table 2, Comparative Examples 1 and 2 have good shear stability and low temperature viscosity, but have low kinematic viscosity, which is disadvantageous in terms of durability and rattle noise. Comparative Examples 3 to 6 have high viscosity at high temperatures and are good in terms of durability and rattle noise, but are inferior to Examples 1 to 3 in terms of low temperature viscosity and shear stability. Examples 1 to 3 have viscosity of 11.2 to 11.3 at high temperature, which satisfies the durability of the transmission, and shows a good level in terms of rattle noise (11 or more). It was expected to be able to improve the low-temperature shift performance was confirmed to show the most excellent viscosity characteristics than the comparative example.

Claims (4)

78 to 80% by weight of polyalphaolefin (PAO) synthetic base oil,
10 to 12% by weight of polyalkyl methacrylate having a number average molecular weight of 300,000 to 400,000, and
A manual transmission oil composition comprising 8 to 12% by weight of an anti-abrasive agent, a metal-based clean dispersant, a phosphate ester friction modifier, a bis succinimide type ashless dispersant or an extreme pressure additive.
The manual transmission oil composition of claim 1, wherein the base oil has an average kinematic viscosity of 3 to 8 cSt at 100 ° C., a viscosity index of 130 or more, and a pour point of −60 ° C. or less.
The method of claim 1, wherein the polyalkyl methacrylate is C ₁₂ Manual transmission oil composition comprising 60 to 80% by weight of C ₁₅ alkyl methacrylate and 20 to 40% by weight of 2-ethylhexyl methacrylate.
The manual transmission oil composition of claim 1, wherein the antiwear agent is zinc dithiophosphate, the metal-based clean dispersant is calcium sulfonate, and the extreme pressure additive is polysulfide.