JPS59149997A - Lubricating oil composition - Google Patents

Abstract

PURPOSE:A lubricating oil composition with good dispersibility for solid lubricant difficultly causing sedimentation and separation, which is obtd. by mixing lubricating oil with modified low-molecular polytetrafluoroethylene. CONSTITUTION:90-99.999mol% tetrafluoroethylene and 0.001-10mol% fluorine- contg. alpha-olefin of formula CF2=CFR (wherein R is Cl, 1-10C perfluoro- or polyfluoroalkyl or 1-10C perfluoro- or polyfluoroalkyloxy, in which at least one O atom may be contained in the carbon chain of alkyl or alkyloxy) are copolymerized in the presence of a chain transfer agent to obtain modified low-molecular polytetrafluoroethylene (B) of particle size of 0.1-50mum and of number- average MW of 1,000-50,000. Then a liquid lubricating oil (A), liquid at room temp., such as fluoroil is mixed with not more than 30wt% component B.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a lubricating oil composition, and more particularly to a lubricating oil composition comprising a solid lubricant mixed with a lubricating oil.

BACKGROUND OF THE INVENTION Lubricating oil compositions comprising polytetrafluoroethylene mixed with lubricating oils, organic solvents, or water are well known. For example, Japanese Patent Application Laid-Open No. 116798 discloses a solid lubricant (1). A lubricating oil composition is disclosed in which graphite and/or polytetrafluoroethylene are dispersed and mixed in a lubricating oil. This lubricating oil composition was developed to reduce friction loss and wear and prevent seizure, but the solid lubricant in the lubricating oil has poor dispersibility and tends to cause sedimentation and separation of the solid lubricant. . Generally, lubricating oil compositions made by mixing a solid lubricant with a lubricating oil have the disadvantage that the solid lubricant tends to settle and separate.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a lubricating oil composition comprising a solid lubricant mixed with a lubricating oil, in which the solid lubricant has good dispersibility and does not cause sedimentation or separation.

The lubricating oil used in the present invention may be liquid at room temperature, for example, 7. c, Sudomari, NJJ, lawn oil, fluorosilicone oil, animal oil, vegetable oil, mineral oil, paraffinic synthetic oil, etc. Modified low molecular weight polytetra 7/L' oleoethylene of the solid lubricant used in this specification is tetrafluoroethylene 9
0 to 99.999 mol% fluorine-containing α-olefin 0.
001 to 10 mol%, and the fluorine-containing α-olefin to be subjected to copolymerization has the general formula: Compounds represented by fluoro or polyfluoroalkyl μ groups or carbon chains containing one or more oxygen atoms, such as chlorotrifluoroethylene, hexafluoropropylene, perfluoroalkyl vinyl ether, CFg= CFOCH! (CF)nH (where n=
0 to 9), etc. The copolymerization ratio of this fluorine-containing α-olefin is preferably within the above range; if it is smaller than the above range, separation between the lubricating oil and the solid lubricant tends to occur, and if it is larger than the above range, the copolymerization ratio is Because the melting point decreases.

Due to the heat generated when a high load is applied, the copolymer repeatedly melts and condenses, gradually becoming larger particles, which begin to act as foreign substances on lubricated surfaces, reducing the lubricating effect.

This modified low-molecular-weight polytetrafluoroethylene can be produced by polymerizing using a chain transfer agent or by decomposing high-molecular-weight modified polytetrafluoroethylene with W beam, heat, etc., and the particle size is 0.1~ 50 μm, number average molecular weight is 1,000 to 50,000.

The solid lubricant, modified low molecular weight polytetrafluoroethylene, preferably has a weight of 80% by weight based on the lubricating oil.
It is used by adding and mixing up to % by weight.

The lubricating oil composition of the present invention can be used with the above composition alone, but if necessary, surfactants, oiliness improvers, corrosion inhibitors, detergent dispersants, antifoaming agents, viscosity index improvers, and fluorine additives may be added. It is also possible to use a lubricating oil additive such as a lubricating oil additive.

Next, the present invention will be specifically explained with reference to Examples and Comparative Examples.

Example 1 Paraffinic synthetic oil (viscosity 170 CP, 25°C) 90
gK solid lubricant modified low molecular weight polytetrafluoroethylene (copolymer of 99.78 mol% tetrafluoroethylene and 0.22 mol% hexafluoropropylene, particle size 0.2-0.4 μm"; number average molecular weight 5,000-10
．． 000) was added and thoroughly mixed using a turbo disperser. 25m of this mixture is 14M@Me x 1
The mixture was placed in a 60-mm test tube, sealed, and allowed to stand upright at 25°C for 72 hours to measure the degree of sedimentation.

The degree of sedimentation here refers to the value obtained by dividing the length from the bottom of the test tube to the liquid level 6) by the length B) from the liquid level to the top of the settled solid lubricant, multiplied by 100. It is expressed by the formula: %, and a small value of the degree of sedimentation (%) indicates good dispersibility in terms of sedimentation and separation.

The results are shown in Table 1.

Examples 2 to 8 Using the modified low molecular weight polytetrafluoroethylene of the solid lubricant shown in Table 1, mixing and measurement of the degree of sedimentation were carried out in the same manner as in Example 1, except for the same procedure as in Example 1.

The results are shown in Table 1.

Comparative Examples 1 and 2 / Using the low molecular weight polytetrafluoroethylene of the solid lubricant shown in Table 1, mixing and measurement of the degree of sedimentation were performed in the same manner as in Example 1, except for the same procedure as in Example 1.

The results are shown in Table 1 together with Examples 1-8.

Claims (1)

[Scope of Claims] 1. A lubricating oil composition comprising a mixture of a lubricating oil and modified low molecular weight polytetrafluoroethylene. 2. The modified low molecular weight polytetrafluoroethylene is tetrafluoroethylene 90-99.999-e. The lubricating oil composition according to the above item 1, which is a copolymer with 10 to 10 mol% of fluorine-containing α-olefin o, ooi. 8. The lubricating oil composition according to item 1 above, in which less than 80% by weight of modified low molecular weight polytetrafluoroethylene is mixed.