KR20050056329A - Composite of lubricant oil for shock absorber - Google Patents

Abstract

The present invention relates to a lubricant composition for a shock absorber, comprising 83 to 92% by weight of mineral oil as a base oil, friction modifier, sludge inhibitor and dispersant, viscosity index improver, antioxidant, antifoam, lubricant and pole It comprises 8 to 17% by weight of an additive including an oppressive agent. According to the present invention, by using only mineral oil as the base oil, by appropriately selecting the type and composition of the additives, such as excellent friction reducing effect, excellent anti-foaming, minimizing the viscosity change of the oil due to high temperature change, chemical resistance to nitrogen gas, proper kinematic viscosity, etc. Lubricants can be provided at very low cost while satisfying the characteristics.

Description

Composition of lubricant oil for shock absorbers

The present invention relates to a lubricating oil composition for a shock absorber, and more particularly to a lubricating oil composition using mineral oil as a base oil as an oil for shock absorbers and the like.

The shock absorber, one of the representative shock absorbers, is mounted under the vehicle body of automobiles, construction machinery, farm equipment, and two-wheeled vehicles to absorb vibration of the vehicle body up and down according to the impact transmitted from the road surface to the vehicle. It aims to increase the service life by improving the load, protecting the cargo loading and reducing the dynamic stress of each part of the body, and also restraining the movement under the spring to secure the tire groundability and suppress the change caused by the inertia force to improve the vehicle's movement performance. .

In the shock absorber, such vibration suppression force is generally referred to as damping force. Generally, there are a mechanism of generating damping force using a method of using solid friction and a method using a fluid pressure. Shock absorbers used in automobile suspensions are lightweight, compact and relatively large in terms of absorbed energy, and the damping force characteristics of the operating speed can be arbitrarily determined. It is used.

Looking at the general structure of the shock observer, a portion of the cylindrical outer tube connected to the wheel is inserted into the cover connected to the vehicle body, the outer tube includes an inner tube (in tube) again, An oil cylinder formed from the cover extends into the inner tube. Lubricating oil and nitrogen gas are filled inside the inner tube. If the impact occurs due to irregularities in the bottom of the road surface while the vehicle is running, the cover and the outer tube are compressed while the lubricant is discharged into the space between the outer circumferential surface of the inner tube and the inner circumferential surface of the outer tube through the small tube of the inner tube. State) Absorbs the shock, and when it returns to the road surface state of the impact-free plane, the cover and the outer tube are tensioned as the lubricant returns to its original position.

Lubricants used in the shock absorber penetrate into the sliding surfaces of the inner and outer tubes, so the friction coefficient must be extremely low, and there should be no disassembly when mixing with nitrogen gas. It should have minimum viscosity change in heat, self-decomposition ability against oil sludge caused by friction between inner tubing and outer tube, and vehicle with minimum viscosity change at low temperature in black region and winter operation. It should provide optimum convenience for driving.

Conventional shock absorber lubricants that satisfy these characteristics include products manufactured by Japanese ax cots, US Delphi, Germany Sachs, etc., and mostly synthetic oils (PAO, ester 界) are mainly used.

However, the above-described conventional shock absorber lubricants are very expensive, but are currently being produced in order to pay a large amount of royalties due to imports from foreign countries or technical cooperation.

In addition, in the existing lubricating oil for shock absorbers, efforts have been made to reduce the frictional force as much as possible in the apparatus in motion, but have not yet achieved a perfect effect.

Under this background, there is a strong need for new lubricants, which have superior friction reduction effects than existing lubricants, but have very low production costs.

Accordingly, it is an object of the present invention to provide a new lubricant composition which is inexpensive while having all the characteristics to be provided for the shock absorber lubricant.

In particular, it is an object of the present invention to provide a lubricating composition which uses mineral oil as base oil instead of synthetic oil which has been used as base oil in existing lubricating oils.

In addition, another object of the present invention is to provide a lubricant composition excellent in friction reduction effect.

The lubricant composition for a shock absorber according to the present invention includes 83 to 92% by weight of mineral oil as a base oil, a friction modifier, a sludge inhibitor and a dispersant, a viscosity index improver, an antioxidant, an antifoaming agent, a lubricating agent and an extreme pressure agent. It comprises 8 to 17% by weight of an additive comprising a.

The additive, based on the content of the total composition, the additive is 5 to 7% by weight of a friction modifier selected from dimethylallylphosphate or dinonyl naphthalene sulfonate (Dinonyl naphthalene sulfonate), calcium sulfonate ( Sludge inhibiting and dispersing agent selected from polymers including calciumsulfonate, triphenylsulfonate and nitrogen 1 to 2.0% by weight, polymethacrylate, polybutylene, polyacrylate 3 to 5% by weight of viscosity index improver selected from (polyacrylate), 0.1 to 1.0% by weight of antioxidant selected from BHT zinc dithiophosphate, organic sulfite, bisphenol-based, silicone polymer as antifoaming agent 0.01 to 1.0% by weight, selected from tricresyl phosphate or chlorinated paraffin It is included in the lubricant and the extreme pressure agent 0.1% to 1.0% by weight.

In the lubricating composition for a shock absorber according to the present invention, the kinematic viscosity of mineral oil as base oil is 7 to 9 (cSt / 40 ° C.), and the kinematic viscosity of the additive has a range of 8 to 15 (cSt / 40 ° C.).

Such a composition has excellent friction lowering effect, stability against temperature change, and good antifoaming property. In particular, while using only 100% mineral oil as a base oil, it is characterized by the effect of friction modification (friction modification) that exceeds the existing lubricants by properly selecting the additive type and composition ratio.

Lubricants such as engine oil and shock absorber oil are largely composed of base oil and additives, and are manufactured by heating and blending them according to a desired quality standard. Base oils include paraffinic base oils, naphthenic base oils, and aromatic base oils. Each component is contained in a certain amount in the base oil, and the base oil accounts for 70 to 90% of the lubricant product.

Since base oil accounts for more than 80% of the lubricating oil component, good base oils are essential for high performance lubricants. Base oil should be excellent in viscosity maintaining ability, protects machinery by forming strong oil film even in heat and cold, and has excellent thermal / oxidation stability for long lasting lubricating oil performance.

In the lubricating oil composition of the present invention, the base oil is a mineral oil rather than a synthetic oil. In particular, a highly refined mineral oil having little wax component is used, and a paraffinic oil having almost no sulfate ash is used.

Synthetic oil base oils are usually prepared by starting from petroleum and combining low molecular weight compounds into compounds having a viscosity suitable for lubricating oil, while mineral oil base oils are obtained from crude oil as a complex of hydrocarbon compounds present in nature.

The present invention by using such a mineral oil as a base oil can provide a part as a base oil to the sludge production inhibitory effect, which had to rely only on the additives, the effect of suppressing the viscosity change of the oil due to changes in the external environment. It also provides a lubricant composition with minimized friction modifiers that play a critical role in the life of the shock absorber.

In the lubricating oil composition of the present invention, base oil is one obtained by centrifugation of wax from mineral oil at low temperature. This improves the low temperature fluidity of the mineral oil as base oil and has a kinematic viscosity in the range of 7 to 9 (cSt 40 ° C.).

On the other hand, the lubricating oil composition of the present invention is based on mineral oil, but the stability of the lubricating oil by adding a small amount of synthetic oil (for example, poly alpha olefin, diester, or polyol ester) to the extent that the manufacturing cost is not seriously increased. You can also improve.

Next, the additive used for the lubricating composition of this invention is demonstrated. The additive is added to the base oil in accordance with various performances required for lubricating oils, for example, a clean dispersant, an antioxidant, a viscosity index improver, a pour point depressant, an antifoaming agent, and the like.

The lubricating oil composition of the present invention can be obtained from a lubricating oil using a conventional synthetic oil as base oil by adding dimethylaryl phosphate sulfate or dinonyl naphthalin sulfonate in an amount of 5 to 7% by weight based on the weight of the total composition. Better friction reduction effect can be obtained.

These effects were compared to the friction degree by applying a force of 20 Newton to the friction rotating body of RPM 5.2 mm / sec, it was confirmed that the lubricating oil according to the present invention shows a better friction reduction value than the lubricating oil using the conventional synthetic oil as a base oil Could.

The lubricating oil composition of the present invention also adds 1 to 2.0% by weight of a sludge inhibiting and dispersing agent selected from polymers including calcium sulfonate, triphenylsulfonate and nitrogen based on the weight of the total composition. This results in sludge suppression and dispersion, which are ideal for base oils of the compositions of the invention. When the amount of the sludge suppression and the dispersant is large, there may be an adverse effect of depositing the residue. Therefore, it is preferable that the amount is not more than 2%.

In addition, the lubricating oil composition of the present invention comprises at least one viscosity index improver such as polymethacrylate. The amount of addition is in the range of 3 to 5% by weight based on the weight of the total composition is appropriate, it is better not to add excessive amount because it is rather decomposed from the base oil during operation. Other useful viscosity index improvers include polybutylene, polyacrylates, styrene maleic esters, and hydrogenated styrene.

In addition, about 0.1 to 1.0% by weight of zinc dithiophosphate, organic sulphate, bisphenol group, and the like are added as antioxidants, and as an antifoaming agent, silicone is added. The polymer is added 0.01 to 1.0% by weight.

In addition, 0.1-1.0% by weight of tricresyl phosphate or paraffin chloride is added as a lubrication and extreme pressure additive.

Lubricants prepared by incorporating such an additive into mineral oil finally maintain a kinematic viscosity of 11 to 15 (cSt / 40 ° C.).

On the other hand, as long as all of the above compositions are satisfied and the characteristic effects according to the present invention are maintained, the shock absorber oil for automobiles, the shock absorber oil for agricultural or construction machinery, and the door closer mounted to the opening and closing device of the fire door are provided. In addition, a suitable amount of other additives may be included in the lubricating oil composition of the present invention to have the basic performance required in the lubricating oil of the gas cylinder of the vehicle front hood and the rear hood.

In order to confirm the effect of the lubricant composition according to the present invention, the friction coefficient, which is a very important factor in the life of the shock absorber, and the degree of change in tension and compression were measured. In the experiment, the lubricating oil according to the present invention and the shock absorber using the existing foreign imported oil were subjected to tension and compression four times at 22 ° C., and then heated to 80 ° C., and then subjected to tension and compression four times at 22 ° C. again. The experimental results are shown in Table 1 below.

Measurement results of friction coefficient and degree of change in tension and compression division Test speed (m / s) Test result by oil sample (Newton) T company oil (Japan) Oil of the invention Company M oil (the United States) min max Deviation min max Deviation min max Deviation Seal 0.052 93 109 16 99 117 18 100 125 25 0.13 354 384 30 370 399 29 377 457 80 0.26 854 872 18 877 908 31 879 938 59 0.39 994 1027 33 1008 1040 32 1022 1075 53 0.52 1137 1177 40 1145 1176 31 1168 1222 54 1.04 1902 1941 39 1861 1898 37 1919 1977 58 1.56 2900 2943 43 2799 2840 41 2939 2995 56 compression 0.052 75 107 32 72 92 20 68 84 16 0.13 125 141 16 119 138 19 98 119 21 0.26 198 211 13 199 216 17 161 198 37 0.39 253 263 10 251 269 18 226 258 32 0.52 306 320 14 300 317 17 280 315 35 1.04 527 551 24 498 527 29 524 565 41 1.56 789 821 32 750 783 33 810 845 35 Average 26 26 43

From the results of Table 1, it can be seen that the lubricating oil composition according to the present invention exhibits the same or better effect than the foreign lubricants currently in use in the friction reduction effect during tension and compression, which are the absolute conditions of the shock absorber oil. Can be. In other words, it can be seen that the lubricating oil composition based on mineral oil is not inferior in terms of effect, but surpasses, compared with conventional oils based on synthetic oil, which is 3-4 times more expensive than this.

In addition to what has been described above, the lubricating composition according to the present invention will be able to obtain the desired properties by using a variety of known additives commonly used in the same art as the present invention.

Lubricant composition of the present invention, while using a low-cost mineral oil as a base oil, the friction reducing effect that the buffer lubricating oil must be provided, excellent anti-foaming, minimizing the viscosity change of the oil due to high temperature change, chemical resistance to nitrogen gas, appropriate It satisfies all characteristics such as kinematic viscosity.

Therefore, it is expected to prevent foreign currency outflow and to greatly increase exports by replacing foreign lubricants used in the past.

Claims (5)

Base oil is composed of 83 to 92% by weight of mineral oil and 8 to 17% by weight of additives, The additive is 5 to 7% by weight of a friction modifier selected from dimethylallylphosphate or dinonyl naphthalene sulfonate, calciumsulfonate, triphenylsulfonate, nitrogen Sludge inhibiting and dispersing agent selected from polymers containing nitrogen 1 to 2.0% by weight, viscosity index improver selected from polymethacrylate, polybutylene, polyacrylate 3 to 5 %, BHT zinc dithiophosphate, organic sulfite, 0.1-1.0 wt% antioxidant selected from bisphenol-based, 0.01-1.0 wt% silicone polymer as antifoaming agent, tricresyl phosphate Or 0.1 to 1% by weight of lubricating and extreme pressure additives selected from chlorinated paraffin Lubrication composition for a shock absorber according to claim.       The lubricating composition for a shock absorber according to claim 1, wherein the mineral oil is a paraffinic oil obtained by removing a wax component and sulfuric acid ash through a refining process.        The lubricating composition for a shock absorber according to claim 1, wherein the mineral oil has a kinematic viscosity of 7 to 9 (cSt / 40 ° C) and the additive has a kinematic viscosity of 8 to 15 (cSt / 40 ° C).        The lubricant composition for a shock absorber according to claim 3, wherein the composition has a kinematic viscosity of 11 to 15 (cSt / 40 ° C).        The lubricating composition for a shock absorber according to claim 1, wherein the composition is used for shock absorber oil of a vehicle, door closer lubricating oil, and lubricating oil of a gas cylinder for a vehicle.