KR20190012156A - lubricant - Google Patents

Abstract

Discloses a lubricant suitable for use as a buffer fluid. The lubricating oil comprises at least 40% by weight of the GTL base oil, based on the weight of the lubricating oil, and has a viscosity index in the range of 50 to 1000, and a pour point of less than -30 占 폚.

Description

lubricant

The present invention relates to a lubricant suitable for use as a shock absorber. The invention also relates to the use of lubricating oils in shock absorbers.

A shock absorber (also referred to as a damper) is a mechanical device designed to mitigate or attenuate sudden shock impulses and dissipate kinetic energy. The shock absorber is an important part in the support of automobiles, motorcycles or bicycle suspensions, aircraft landing gears, train suspensions and many industrial machines. Large buffers are also used in construction and civil engineering to reduce the susceptibility of structures to earthquake damage and resonance.

The shock absorber can dissipate kinetic energy into thermal energy. The hydraulic shock absorber consists of a cylinder with a sliding piston inside. The cylinder is filled with buffer fluid. This fluid-filled piston / cylinder combination is also referred to as a dashpot. Wheel suspension in a vehicle usually includes several shock absorbers with pressure elastic means such as coil springs, leaf springs or torsion bars. This spring is simply a spring that does not waste, absorb, or absorb energy and is not a buffer. As the wheel moves horizontally, the spring will absorb the up and down forces and convert it to heat. The shock absorber damps the wheel bounce effectively by decelerating the motion of the non-spring weight up and down with a hysteresis, such as a tire of a wheel, for example. This is achieved by converting the kinetic energy to heat through fluid friction due to the flow of buffer fluid through a narrow orifice, such as an inner valve.

WO201063752 discloses a fluid which can be used as a buffer fluid having high biological degradability and high compatibility with viscosity improvers, especially at low temperatures. The fluid comprises a base oil composition and a viscosity index improver. Base oil compositions include esters of GTL base oils and polyhydroxy compounds.

The inventors have sought to provide a lubricant suitable for use as a buffer fluid having advantageous properties, for example, longer period shear stability and / or lower temperature viscosity characteristics than commercially available buffer fluid.

The inventors have found that suitable lubricating oils for use as buffer fluids can be prepared from a beneficial combination of GTL base oils, alkylbenzenes or alkylnaphthalenes and viscosity modifiers. Such combinations exhibit excellent shear stability and good low temperature viscosity.

Accordingly, the present invention provides a lubricating oil comprising:

(a) 40 wt.% or more of a GTL base oil based on the weight of the lubricating oil;

(b) from 5 to 25% by weight, based on the weight of the lubricating oil, of alkylbenzene or alkylnaphthalene; And

(c) 0.1 to 20% by weight, based on the weight of the lubricating oil, of a viscosity index improver;

The lubricating oil has a viscosity index in the range of 50 to 1000, and a pour point of less than -30 占 폚.

Lubricants are suitable for use in shock absorbers, but can also be used as industrial lubricants such as fork or hydraulic oils, bearings and circulating oils.

The present invention further provides the use of a lubricant according to the present invention in a shock absorber.

The present invention further provides a vehicle comprising lubricant according to the present invention.

The lubricating oil comprises at least 40% by weight of the GTL base oil based on the weight of the lubricating oil. The lubricating oil preferably comprises 50 to 90 wt.%, More preferably 60 to 85 wt.% Of the GTL base oil, based on the weight of the lubricating oil.

The term " GTL base oil " is used to describe a base oil that is synthesized by the Fischer-Tropsch method of converting natural gas to liquid fuel. They have a very low sulfur content and aromatic content and a very high paraffin composition ratio compared with mineral oil refined from crude oil. The GTL base stock may be a mixture of several different GTL base oils having different viscosities. The dynamic viscosity of the GTL base oil is preferably in the range of 2 to 10 mm ² / sec, more preferably 2.5 to 7 mm ² / sec at 100 ° C. The dynamic viscosity is suitably determined according to ASTM D445. Suitable base oils known as "GTL 4" and "GTL 3" are available from Shell.

The lubricating oil comprises from 5 to 25% by weight of alkyl benzene or alkyl naphthalene based on the weight of the lubricating oil. Suitably the alkylbenzene or alkylnaphthalene is a mixture of different alkylbenzene molecules and / or alkylnaphthalene molecules. Alkylbenzenes and / or alkylnaphthalenes may be mono- or poly-substituted, but are preferably mono- or disubstituted. In a preferred embodiment, the lubricating oil comprises a mixture of 5-25% by weight of alkylbenzenes mono- or di-substituted with linear and / or branched alkyl groups and the alkyl group is a C ₆ -C ₂₀ alkyl group, preferably C ₉ is a -C ₁₅ alkyl group. The dynamic viscosity (determined by ASTM D445 as appropriate) of the alkylbenzene or alkyl naphthalene at 40 DEG C is preferably 3 to 400 mm ² / s, preferably 3 to 50 mm ² / s and more preferably 3 to 10 mm ² / s is appropriate. The average relative molecular weight is suitably from 180 to 300, preferably from 200 to 280, more preferably from 230 to 260. [

The lubricating oil comprises from 0.1 to 20% by weight, based on the weight of the lubricating oil, of a viscosity index improver. The lubricating oil preferably comprises 1 to 18% by weight, more preferably 3 to 10% by weight, of a viscosity index improver.

Viscosity index improvers (also referred to as VI improvers, viscosity modifiers, or viscosity improvers) provide high and low temperature operability to lubricants. These additives impart shear stability and allowable viscosity at elevated temperatures and low temperatures. Suitable viscosity index improvers include both low molecular weight and high molecular weight hydrocarbons, polyesters and viscosity index improvers and viscosity index improver dispersants that can function as both dispersants. Typical molecular weights of these polymers are from about 10,000 to 1,000,000, more usually from about 20,000 to 500,000, and more typically from about 50,000 to 200,000. Examples of suitable viscosity index improvers are polymers and copolymers of methacrylate, butadiene, olefins or alkylated styrenes.

Preferably, the viscosity index improver is polymethylmethacrylate (also referred to as PMMA), i.e. a copolymer of methyl and alkyl methacrylates of various chain lengths. A particularly preferred PMMA viscosity index improver is the commercially available Viscoplex viscosity improver (Viscoplex is the trade name of Rohm GmbH & CO. (KG, Darmstadt, Germany)).

The lubricating oil suitably further comprises one or more additives typically used in the buffer fluid. These additives may be added in the form of an additive package. Typical additive packages include antioxidants and antiwear agents, but may also include additives such as dispersants, detergents, rust inhibitors, metal deactivators, extreme pressure additives, foam inhibitors, pour point depressants, wax modifiers, sealants, friction modifiers, lubricants, Coloring agents, antifoaming agents and antidotes.

The lubricating oil preferably comprises a wear resistant additive. Suitable abrasion resistant additives typically include metal containing and metal free alkyl thiophosphates such as zinc dialkyl dithiophosphates used in amounts of from about 0.4% to about 1.4% by weight of the lubricating oil.

The lubricating oil preferably comprises a defoaming agent. Silicone and organic polymers are typical antifoaming agents. Preferably, the defoamer is a low-silicone or no-silicone defoamer such as an acrylic copolymer or fatty amine ethoxylate. The amount of antifoaming agent is suitably less than 1% by weight, preferably less than 0.1% by weight, more preferably less than 0.05% by weight, based on the weight of the lubricating oil.

The lubricating oil has a viscosity index in the range of 50 to 1000, preferably in the range of 100 to 600. [ A suitable viscosity index is determined according to ASTM D2272. If the viscosity index is too low, the lubricating oil will tend to be too viscous at low temperatures and too thin at high temperatures, and then the lubricating oil will not effectively function in the buffer.

The lubricating oil preferably has a pour point of less than -30 占 폚, preferably less than -45 占 폚. Suitably the pour point is determined according to ASTM D97. If the lubricating oil has a higher pour point, the fluid does not flow under cold ambient conditions and the buffer containing fluid does not work.

The lubricating oil suitably has a kinematic viscosity at 40 캜 of at least 7 mm ² / s, preferably at least 10 mm ² / s and more preferably at least 12 mm ² / s. Suitably the kinematic viscosity is determined according to ASTM D445 at 40 占 폚. It is important to have this viscosity in order for the lubricant to work effectively in the buffer.

The lubricating oil suitably has a Brookfield viscosity of less than 2000 cP at -40 캜, more preferably less than 1500 cP, and most preferably less than 1250 cP. The Brookfield viscosity at -40 캜 as appropriate is determined by ASTM D2983. It is important to have this viscosity in order for the lubricant to work effectively in the buffer.

The lubricating oil suitably has a shear stability of less than 10%, more preferably less than 5%, most preferably less than 3%, measured according to CEC L-45-99 at 40 占 폚. It is important that lubricants have the highest possible shear stability (the least shear stability loss possible under test conditions), so that when used in shock absorbers, lubrication oils have the correct viscosity range for efficient operation for as long as possible. If the shear stability of the lubricating composition is low, the shear rate and viscosity will soon be out of range.

Hereinafter, the present invention will be described with reference to examples, but the present invention is not limited thereto.

Example

Having the composition shown in Table 1 A buffer fluid (Example 1) was prepared:

Table 1

Two GTL base stocks are purchased from Shell. The GTL 4 base oil has a viscosity of 3.80 to 4.20 cSt at 100 캜 (as measured by ASTM D445). The GTL 3 base oil has a viscosity of 2.8 cSt at 100 캜 (as measured by ASTM D445). The alkylbenzene was a mixture of mono-substituted alkylbenzenes having a kinematic viscosity of 3 to 5 mm ² / s at 40 ° C. The fluid was prepared by mixing all components and heating until a homogeneous mixture was formed.

Test

The buffer fluid of Example 1 and two commercial buffer fluids (Comparative Example 1 and Comparative Example 2) were tested. Table 2 shows the tested properties of Example 1, Comparative Example 1 and Comparative Example 2, the test methods used and the results.

Table 2

The results show that the three buffer fluids have similar densities and viscosities at 40 ° C to 100 ° C and viscosity indices. The buffer fluid of the present invention (Example 1) has an improved Brookfield viscosity compared to commercial buffer fluids (Comparative Example 1 and Comparative Example 2) and also has excellent shear stability.

Claims (8)

As a lubricating oil,
Based on the weight of the lubricating oil, at least 40% by weight of a GTL base oil;
From 5 to 25% by weight, based on the weight of the lubricating oil, alkylbenzene or alkylnaphthalene; And
From 0.1 to 20% by weight, based on the weight of the lubricating oil, of a viscosity index improver,
Wherein the lubricant has a viscosity index in the range of 50 to 1000 and a pour point of less than -30 占 폚.
The lubricating oil of claim 1 comprising from 50 to 90% by weight of a GTL base oil.
3. A method according to claim 1 or 2, wherein the linear and / or branched alkyl group with a single-substituted or di-, and comprises a mixture of alkyl benzene substituted 5 to 25% by weight of the alkyl group is a C ₆ -C ₂₀ alkyl group , Lubricating oil.
4. Lubricating oil according to any one of claims 1 to 3, wherein the viscosity index improver is selected from polymers and copolymers of methacrylate, butadiene, olefin or alkylated styrene.
5. Lubricating oil according to any one of claims 1 to 4, comprising an alkyl thiophosphate containing or not containing a metal in an amount of from about 0.4% to about 1.4% by weight of the lubricating oil.
6. Lubricating oil according to any one of claims 1 to 5, comprising an acrylic copolymer or fatty amine ethoxylate in an amount of less than 0.1% by weight, based on the weight of the lubricating oil.
Use of a lubricating oil according to any one of claims 1 to 6 in a shock absorber.
A vehicle comprising a shock absorber according to claim 7.