JPH03126790A - Lubricating oil composition - Google Patents

Abstract

PURPOSE:To obtain a lubricating oil composition capable of keeping excellent defoaming property over a long period and suitable as engine oil, gear oil, hydraulic fluid, automatic transmission oil. bearing oil, etc., by compounding a specific amount of a perfluoroether as an essential component. CONSTITUTION:The objective composition is produced by using a perfluoroether preferably expressed by formula [R1 and R2 are 1-4C perfluoroalkyl; R3 is 1-4C perfluoroalkylene; (n) is integer of >=2 (preferably 10-300)] as an essential component and adding 1-1.000wt.ppm of the perfluoroether to a synthetic or mineral base oil having a viscosity range of preferably 2-1,000cSt (at 40 deg.C).

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a lubricating oil composition, and more specifically, it is used for applications such as engine oil, gear eraser, hydraulic oil, automatic transmission oil, bearing oil, etc., and has excellent properties. The present invention relates to a lubricating oil composition having antifoaming properties.

[Prior Art and Problems to be Solved by the Invention] Lubricating oil is generally used in circulation in order to save the amount used. Therefore, the oil that has passed through the lubricating section returns to the oil sump. Since the oil traps air in the lubricating oil section, the water that returns to the oil sump is usually bubbling. If these bubbles persist, they will gradually increase and eventually the oil will be blown out of the oil sump.

For this reason, lubricating oils are required to have antifoaming properties.

In order to improve the antifoaming properties of lubricating oils, antifoaming agents such as silicone oil and polyacrylate have conventionally been added to base oils.

Silicone oil is an excellent antifoaming agent, but it becomes more soluble in light oils and its antifoaming function is significantly reduced. Moreover, silicone oil deteriorates due to long-term use, harsh use conditions, or coexisting chemical substances, and in that case, the antifoaming function is lost.

In addition, polyacrylate has poor defoaming function, and there has been a desire for an antifoaming agent that can solve the above problem.

On the other hand, perfluoroether is known as a synthetic lubricating base oil, but because it hardly mixes with other mineral oils or synthetic oils, it has never been used as a minor component of lubricating oils.

An object of the present invention is to provide a lubricating oil composition which has excellent antifoaming properties and whose antifoaming properties do not deteriorate much even under long-term or severe conditions.

As a result of repeated research in line with the above objectives, the present inventors discovered that adding a small amount of perfluoroalkyl ether to lubricating oil provides excellent antifoaming properties, leading to the completion of the present invention. .

[Means for Solving the Problems] That is, the present invention provides a lubricating oil composition characterized by containing perfluoroether as an essential component in an amount of 1 to 1000 wtpI)m based on the total amount of the composition. .

Hereinafter, the content of the present invention will be explained in more detail.

As the base oil used in the lubricating oil composition of the present invention, any base oil that is normally used as a lubricating base oil can be used, regardless of whether it is a mineral oil type or a synthetic type.

For example, for mineral oil-based lubricating oils, the fraction obtained by distilling mineral oil under normal pressure or under reduced pressure can be used by solvent membrane filtering, solvent extraction,
Those purified by appropriate combinations of hydrogenolysis, solvent membrane waxing, hydrocharcoal waxing, sulfuric acid washing, clay purification, hydrogenation refining, etc. are used.

Specific examples of synthetic lubricating oils include normal paraffin, imparaffin, polybutene, polyisobutylene, α-olefin oligomers such as 1-decene oligomers, alkylbenzenes such as monoalkylbenzene, dialkylbenzene, and polyalkylbenzene, Alkylnaphthalenes such as alkylnaphthalenes, dialkylnaphthalenes and polyalkylnaphthalenes, diesters such as di-2-ethylhexyl sebacate, dioctyl adipate, diisodecyl adipate, ditridecyl adipate and ditridecyl glutarate, trimethylolpropane caprylate, trimethylolpropane Polyol esters such as caprylate, pentaerythritol-2-ethylhexanoate, and pentaerythritol belargonate; polyglycols such as polyethylene glycol, polyethylene glycol monoether, polypropylene glycol, and polypropylene glycol monoether; polyphenyl ether; Examples include cresyl phosphate and silicone oil.

In the present invention, these oils may be used alone or in combination. It can also be used by mixing the above.

The preferred viscosity range of the base oil is 2 to 1 at 40°C.
It is the oosest. As the perfluoroether which is an essential component in the present invention, those having various structures can be used, but preferably the perfluoroether type (1) or a mixture of two or more types of perfluoroethers represented by the general formula are used. In the above formula, R4 and R2 may be the same or different,
Each represents a straight chain or branched perfluoroalkyl group having 1 to 4 carbon atoms, and R3 is a straight chain or branched perfluoroalkyl group having 1 to 4 carbon atoms.
+1 perfluoroalkylene group is shown.

Further, n represents an integer of 2 or more, preferably 10 to 300. Specifically, R1 and R2 include perfluoromethyl group, perfluoroethyl group, perfluoropropyl group, 1so-perfluoropropyl group, perfluorobutyl group, 1so-perfluorobutyl group, 5eC-perfluorobutyl group. group, tert-perfluorobutyl group, and the like. Further, R3 specifically includes perfluoromethylene group, perfluoroethylene group, perfluorotrimethylene group, perfluoropropylene group, perfluorotetramethylene group, perfluorobutylene group, perfluoro 1,2
-dimethylethylene group, perfluoro 1-methyltrimethylene group, perfluoro 2-methyltrimethylene group, etc.

In the perfluoroether in the present invention, different perfluoroalkylene groups may be present in one molecule. In that case, different perfluoroalkylene groups may be randomly copolymerized or block copolymerized.

Furthermore, the viscosity of the perfluoroether in the present invention is
Although not particularly limited, usually 10 to 1000
0 cst, @20℃, preferably 20-200
0cst @20°C. The average molecular weight is also not particularly limited, but is usually 500 to 500.
00, preferably 1800 to 10000.

In the lubricating oil composition of the present invention, the content of the perfluoroether is 1 to 1000 wtp1 based on the total amount of the composition.
000, preferably 3 to 100 wtppm. Perfluoroether content is Iwtp
If it is less than 1000 pm, sufficient antifoaming effect cannot be obtained.
If it exceeds wtppm, it is not preferable because there is a possibility of sedimentation and separation.

The lubricating oil composition of the present invention may contain known additives as necessary for the purpose of further enhancing its performance. Such additives include, for example, antioxidants, detergent dispersants, viscosity index improvers, pour point depressants, oil agents, antiwear agents, extreme pressure agents, corrosion inhibitors, metal deactivators, and rust inhibitors. agents, other antifoaming agents, emulsifiers, demulsifiers, bactericidal agents, coloring agents, and the like. Details of these various additives can be found, for example, in “Lubricating Oil Academic Policy Vol. 15, No. 6” or “Toshio Sakurai (ed.),”
"Petroleum Product Additives" (Saiwai Shobo)" etc. These additives are appropriately selected depending on the use of the lubricating oil. The lubricating oil composition of the present invention contains essential components such as Compared with conventionally known antifoaming agents, fluoroether is less likely to deteriorate due to interaction with other additives, and other additives can be selected from a wide range, so it is also superior in this respect.

The total amount of these various additives added is usually 50 wt% or less, preferably 30 wt% or less, based on the total amount of the composition.

The lubricating oil of the present invention includes engine oil (4-cycle gasoline engine oil, 2-cycle gasoline engine oil, land diesel engine oil, marine diesel engine oil, gas engine oil, etc.), turbine oil (industrial turbine oil, marine turbine oil, etc.). , gas turbine oil, etc.), gear oil (automotive gear oil, industrial gear oil, automatic transmission oil, etc.), hydraulic oil, compressor oil, vacuum pump oil, refrigeration oil, metal processing oil (cutting oil, grinding oil, Rolling oil, press oil, drawing oil, drawing oil
It is preferably used for various purposes such as ironing oil, rolled parts, forged parts, etc.), sliding guide surface parts, and bearing oil.

[Effects of the Invention] Since the lubricating oil composition of the present invention contains a small amount of perfluoroether, (1) it is possible to prevent foaming of light oils, / (2) defoaming due to deterioration. (3) It is now possible to use lubricating oil additives that could not be used because they degrade silicone oil, etc. It is an excellent lubricating oil composition with the following characteristics.

[Examples] Hereinafter, the content of the present invention will be explained in more detail with reference to Examples and Comparative Examples.

Example 1 and Comparative Example 1 Industrial bearing oil (base oil viscosity 220C8t, @40℃
perfluoroether (product name).

Pombljn Y25, viscosity 250 cst,
@20°C, molecular weight 3000, manufactured by Asahi Glass ■) to the total amount of oil (Example 1) and silicone oil (3000cs) in place of perfluoroether.
An oxidation test was conducted on the product (Comparative Example 1) in which 30 wtppm of t, @25°C) was added to the total amount of oil, and then a foaming test was conducted.

The test conditions and foaming test results are shown below.

Oxidation test: Based on JIS K 25143.1, 15
The song was oxidized at 0°C for 120 hours.

Foaming test: Based on JIS K 2518, 24°C
The test was conducted.

Foaming test results: Automotive transmission oil (base oil viscosity 14 cst
, @too℃ mineral oil type) and perfluoroether (
Product name: Pombljn Y45, viscosity 250c
st.

@20℃, molecular weight 3000, manufactured by Asahi Glass ■) to the total amount of oil (Example 2) and polyacrylate instead of perfluoroether to the total amount of 200 wtppm of the oil (Comparative Example 2) An oxidation test was conducted, and then a foaming test similar to that in Example 1 was conducted. The oxidation test conditions and foaming test results are shown below.

Oxidation test: Based on JIS K 25143.1, 1
The oil was oxidized at 50°C for 100 hours.

Foaming test results

Claims (1)

[Claims] 1. A lubricating oil composition containing 1 to 1000 wtppm of perfluoroether as an essential component, based on the total amount of the composition.