JPH02242893A - Lubricating oil composition - Google Patents

Abstract

PURPOSE:To provide a lubricating oil composition exhibiting a good dispersibility of graphite fluoride at both low and high temperatures by dispersing the graphite fluoride in a non-polar base oil with a dispersing agent containing oxybutylene groups. CONSTITUTION:Graphite fluoride particles having an average particle size of 0.02-10mum preferably in an amount of 0.05-50% is dispersed in a non-polar base oil with a dispersing agent preferably having three or more oxymethylene groups [preferably R<1>O-(C4H6O)mH, R<1>O-(C4H8O)mX-(OC4H8O)nOR<2> (R<1> and R<2> are preferably 1-20C alkyl, alkylphenyl or acyl; X is preferably 1-4C alkylene; m and n are preferably >=3)]. The preferable examples of the non-polar group are liquids such as paraffinic hydrocarbons, naphthenic hydrocarbons, olefinic polymerized oils, alkylated aromatic oils, animal and vegetable oils, etc., having viscosities of usually 5-3,000cp (ordinary temperature).

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a lubricating oil composition having good dispersibility of fluorinated graphite.

[Conventional technology] Mineral oil,
Various solid and liquid additives are added to lubricating oils such as synthetic oils and animal and vegetable oils.
, l and (C,F)□ are typical examples. Attempts have been made to add fluorinated graphite to lubricating oil to improve its lubricating properties, such as preventing load-bearing seizure and reducing friction. Kosho 60-567
60, Japanese Patent Publication No. 62-61638, etc., but due to the poor performance of the dispersant used, the fluorinated graphite in the dispersed liquid causes agglomeration and sedimentation within a few hours, resulting in a change in the shape of the fluorinated graphite. In some cases, the settled fluorinated graphite solidified and became clay-like, making redispersion impossible. These trends are particularly noticeable in non-polar lubricating oils.

[Problems to be Solved by the Invention] Fluorinated graphite itself has a property of being extremely incompatible with oil as well as with water. Therefore, the dispersion stability is particularly poor in non-polar lubricating oils, and there are problems in that they readily coagulate and settle.

For example, in order to obtain a practical lubricating oil with improved extreme pressure properties and friction resistance, it is necessary to add fluorinated graphite to the base oil by 0.00%.
However, even if such an amount of fluorinated graphite is mixed with the base oil and mechanically dispersed, This alone causes aggregation and sedimentation of fluorinated graphite.

Various studies have been conducted to improve the dispersion stability of such fluorinated graphite in oil. For example, Japanese Patent Publication No. 60-56760 proposes a lubricating oil composition in which fluorinated graphite particles are dispersed in a lubricating oil using a dispersant containing at least one propylene oxide group in the molecule. However, the dispersant containing a propylene oxide group described in the same publication is subject to extremely limited practical use due to its stability at low temperatures.

In other words, there is a fatal flaw in starting the engine at low temperatures and in lubrication for the refrigerator.

An object of the present invention is to provide a lubricating oil composition in which fluorinated graphite is dispersed in a nonpolar base oil in a stable state without agglomeration or sedimentation, and exhibits similar properties even at low temperatures.

[Means for Solving the Problems] The present invention has been made to solve the above-mentioned problems, and provides a lubricating oil in which fluorinated graphite is dispersed in a non-polar base oil using a dispersant containing an oxybutylene group. A composition is provided.

Furthermore, the present invention also provides a lubricating oil composition in which a carboxyl group-containing surfactant is used simultaneously with the dispersant in order to further stabilize the dispersibility.

The dispersant of the present invention contains a small number (one oxybutylene group, preferably three or more oxybutylene groups) in one molecule. Preferred examples include -
Sailor (I) R'O (C, I (,0) or H or general formula (
H) R'O(C,8,0).

X(OC,8,0),,OR'' [wherein R1 and R2
are the same or different alkyl groups, alkylphenyl groups or acyl groups (preferably each group having 1 to 20 carbon atoms),
X is an alkylene group (preferably one with 1 to 4 carbon atoms)
, where m and n are each an integer of 1 or more (preferably 3 or more). (I) or (II)
The fractional agent exhibits favorable performance due to its high solubility in non-polar base oil and high wettability to fluorinated graphite. These dispersants may further have oxyethylene groups or oxypropylene groups added thereto in a random or block form.On the other hand, the surfactant used in combination with the above-mentioned dispersants is a carboxylate surfactant. Preferably, the general formula (ill
) (RCOO), M (wherein R is an alkyl group having 10 or more carbon atoms, preferably 20 or more carbon atoms, p is an integer of 1 to 2, M
Surfactants represented by alkali metals or alkaline earth metals or lanolin fatty acid salts are preferred because of their low-temperature stability. In the present invention, the amount of the dispersant in the lubricating oil composition consisting of the base oil, fluorinated graphite, the above-mentioned dispersant, and optionally the above-mentioned surfactant is 0.1 to 50%, preferably 1.0 to 20%. However, the surfactant is the same < 0
．． A content of 0.005% to 10%, preferably 0.01% to 7% is preferred because the uniform dispersion state of the lubricating oil composition can be maintained stably for a long period of time.

Next, the fluorinated graphite used in the present invention is preferably in the form of particles, and although the particle size is not particularly limited, the average particle size is usually in the range of 0.02 to 10 microns, and the particle distribution is preferably controlled. Preferably, it is uniform. Further, the amount of fluorinated graphite in the lubricating oil composition according to the present invention is 0.05 to 5.
0% is preferable, and if it is less than 0.05%, the lubrication performance will be inadequate, and if it is more than 50%, the price will be high compared to the performance, which is not preferable.

Next, preferred non-polar base oils for use in the present invention include mineral oils such as paraffinic hydrocarbon oils and naphthenic hydrocarbon oils, synthetic hydrocarbon oils such as olefin polymerized oils, alkylated aromatic oils, and synthetic hydrocarbon oils. They are oils, animal and vegetable oils, etc., and are liquid substances that usually have a viscosity of 5 to 300 Dcp (at room temperature).

[Function] The dispersant obtained according to the present invention dissolves well in non-polar base oil and has high wettability to fluorinated graphite.
Fluorinated graphite has excellent dispersion stability in oil, for example,
Even if left for a long period of time, such as 6 months or more, the
Even at high temperatures such as 90℃, for example -20 to 3
There is very little sedimentation of fluorinated graphite even at low temperatures such as 0°C.

[Example] Reference Example 1 Dispersant A [Structure 2 CL (CHa) r IO (CJa
O) r oH) ]990g fluorinated graphite (particle size 0.2
10 g of micro-particles were uniformly dispersed in a ball mill at room temperature for 10 hours, and the dispersion liquid was placed in a glass tube with an inner diameter of 27 am to observe dispersion stability. Dispersion stability was determined by placing the dispersion to be tested in a stoppered test tube with an inner diameter of 27 m @ up to a height of 50 mm, allowing it to stand at room temperature, and measuring the height of the precipitate.

Reference Example 2 35 g of dispersant A, 5 g of surfactant (lanolin fatty acid calcium salt), and 10 g of fluorinated graphite were dispersed in a ball mill, and the dispersion stability was observed.

Reference Examples 3 to 6 Dispersant B [CHs(CHa) +J(CJaO)xo
H], dispersant C[CH, (mountain) a @0 (C, 8, 0)
Fluorinated graphite was dispersed using a combination of No. 8 and a lanolin fatty acid calcium salt surfactant, and the dispersion stability was observed.

Reference Comparative Examples 1 to 2 Dispersant containing a propylene oxide group and having good compatibility with machine oil [Structure: R'0(CHIGHlCHQ)rI)I
Table 1 shows the dispersion stability of 90 g of R: CH3 (CH2) 1°nJo] and 10 g of fluorinated graphite together with the results of Reference Examples 1 to 6.

Examples 1 to 6, Comparative Examples 1 to 2 Reference Examples 1 to 6 and Reference Comparative Examples 1 to 2 to 97 g of spindle oil
3 g of each fluorinated graphite dispersion were added and mixed. The dispersion stability, friction coefficient, and ultimate load-bearing pressure of the prepared lubricating oil composition were measured. The lubricating oil composition was transferred to a 100 ml graduated cylinder and stored in a constant temperature bath for 90 days, and the sedimentation layer inside the graduated cylinder was observed to determine dispersion stability.

The results are shown in Table 2.

In addition, the symbols in the table mean the following.

O: No sediment was observed.

△: A slight amount of sediment is observed.

×: Sediment is observed.

The friction coefficient was measured using a pendulum type oil-based friction tester (manufactured by Shinko Zoki ■) under standard test conditions. The ultimate load-bearing pressure was measured using a four-ball friction tester (manufactured by Soda Shinko Corporation Ti) using a step method in which a load of 0.5 kg was applied every minute at a spindle rotation speed of 200 rpm.

Table 1

Claims (2)

[Claims] (1) A lubricating oil composition comprising fluorinated graphite dispersed in a nonpolar base oil using a dispersant containing an oxybutylene group. (2) The lubricating oil composition according to claim 1, wherein a carboxylate surfactant is used together with a dispersant containing an oxybutylene group.