JPH01259097A - Grease composition having long life at high temperature - Google Patents

Abstract

PURPOSE:To obtain the title composition useful for manufacturing automobiles, slightly evaporating and oxidizing at a high temperature, having excellent shear stability and adhesivity, by blending a base oil containing an alkyl diphenyl ether oil with a specific amount of a specific diurea compound as a thickening agent. CONSTITUTION:A base oil comprising an alkyldiphenyl ether oil an essential component is blended with 2-35wt.% diurea compound shown by the formula [R1 and R3 are 6-12C aromatic hydrocarbon or 8-20C straight chain alkyl (the ratio of aromatic hydrocarbon group in R1 and R3 is 50-100mol%); R2 is 6-15C aromatic hydrocarbon] as a thickening agent to give the aimed composition.

Description

[Detailed Description of the Invention] (Field of Industrial Application) Mechanical technology has made remarkable progress in recent years, and in the automobile industry, bearings are becoming faster due to smaller and lighter parts, and lubrication points tend to become hotter. . Particularly in electrical components, the lubricating points are directly connected to or near the engine, which is a heat generating element, and the temperature rises significantly. Furthermore, in the steel industry, the number of high-temperature lubrication points is increasing due to the spread of continuous casting equipment and the like.

The present invention meets these lubrication conditions at high temperatures, long life, and
The present invention relates to a highly reliable grease composition.

(Prior Art) Looking at the technology for using grease, lubrication of such high-temperature locations has been addressed, for example, in the automobile industry by early replacement of lubricated parts, and in the steel industry by central lubrication of grease. However, these methods are contrary to the concept of maintenance-free design and resource saving.

Regarding the content of grease, various improvements and inventions have been made in order to obtain a grease that has a long life at high temperatures, and most of these have been related to the base oil and thickener that are the basis of grease.

(Problems to be Solved by the Invention) Under these current circumstances, mineral oil is used as the base oil in many greases on the market. Mineral oil cannot withstand continuous use at high temperatures due to evaporation and oxidative deterioration. Ester oil and poly-α-olefin oil, which are synthetic oils, generally have better heat resistance than mineral oil, but the former lacks viscosity for high-temperature lubrication and is prone to evaporation and oxidative deterioration, while the latter is more susceptible to evaporation and oxidative deterioration.・It has drawbacks such as oxidative deterioration and the formation of sludge due to this, and cannot withstand long-term use at temperatures above 160°C. In terms of thickeners, metal soaps have a thickening structure that is destroyed at high temperatures and cannot withstand long-term use, while clays have drawbacks in lubricity at high temperatures. Urea-based materials exhibit better heat resistance than these, but those whose terminal groups are mainly aliphatic and alicyclic groups have drawbacks in shear stability and poor adhesion to lubricated surfaces. There was a drawback of softening leakage from the lubricated parts.

Therefore, the present invention uses a synthetic oil with excellent heat resistance that exhibits little evaporation, oxidative deterioration, and sludge formation at high temperatures as the base oil, and uses a urea-based compound with excellent shear stability and adhesion as the thickener. By using this product, we can obtain a grease that has a long life at high temperatures, and by providing this highly reliable grease to industry, we aim to promote maintenance-free and resource saving.

(Means for Solving the Problems) The present invention was achieved as a result of intensive research to obtain a grease that has a long life and high reliability at high temperatures. In addition, as a thickener, the following general formula (R2 in the formula is an aromatic hydrocarbon group having 6 to 15 carbon atoms,
R9 and R5 represent an aromatic hydrocarbon group having 6 to 12 carbon atoms or a linear alkyl group having 8 to 20 carbon atoms, and the proportion of the aromatic hydrocarbon group in R5 and R3 is 50
~100 mol%) of the diurea compound represented by 2
The present invention relates to a grease composition that has a long life at high temperatures and is characterized by containing ~35% by weight.

The alkyldiphenyl ether used in the present invention is obtained by the addition reaction of 1 mole of diphenyl ether and 1 to 3 moles of α-olefin having 10 to 22 carbon atoms, and its properties vary depending on the number of carbon atoms in the α-olefin and the number of moles used.
It is a colorless to yellow transparent liquid and is itself a known substance. Regarding alkyldiphenyl ether oil, Japanese Patent Publication No. 44263/1983 describes a rotary pump oil containing alkyldiphenyl ether oil as an essential component.
Seawater resistant hydraulic oil in Publication No. 1722, Special Publication No. 52-246
Publication No. 28 discloses a diffusion pump oil, and Japanese Patent Publication No. 58-22515 discloses a lubricating oil for chains used at high temperatures. In the present invention, the content of alkyldiphenyl ether is not particularly limited, but in order to obtain a grease that has a long life at high temperatures, it should preferably be contained in an amount of 50% by weight or more based on the base oil. The oil is
Examples include mineral oil, ester-based synthetic oils typified by diesters and tetraesters, and synthetic hydrocarbon oils typified by polyα-olefins.

Further, the diurea compound represented by the formula (1) used as a thickener is usually obtained by the reaction of a diisocyanate and a monoamine, and in the present invention, the diurea compound represented by the formula (1) is used as a thickener.
The proportion of aromatic hydrocarbon groups in R1 and R3 in ) is set to 50 to 100 mol%, but the reason for this is that if it is less than 50 mol%, shear stability and adhesion to the lubricated surface may deteriorate. This is because bearings leak significantly at high temperatures and cannot withstand long-term use. The diisocyanates that become R2 after the above reaction include aromatic isocyanates such as 2.4-tolylene diisocyanate, 2.6-)lylene diisocyanate, diphenylmethane-4,4'-diisocyanate, and naphthylene-1,5-diisocyanate; is a mixture and R.I.
Monoamines that become +R1 include aromatic amines such as aniline, benzylamine, toluidine, and chloroaniline; octylamine, nonylamine, decylamine, undecylamine, dodecylamine, tridecylamine, tetradecylamine, pentadecylamine, and hexadecylamine; These are linear amines such as decylamine, heptadecylamine, octadecylamine, nonyldecylamine, and eicosylamine. The amount of the diurea compound blended is 2 to 35% by weight based on the base oil. If the amount is less than 2% by weight, the resulting grease will be fluid, and if it exceeds 35% by weight, it will solidify, so both are suitable for bearings. It is not suitable as a grease to lubricate etc.

Additionally, additives such as antioxidants, rust preventives, extreme pressure agents, oily agents, and solid lubricants may be added to the grease composition of the present invention, if necessary.

(Function) The alkyldiphenyl ether oil used in the present invention has sufficient viscosity at high temperatures, and is comparable to conventional synthetic oils, i.e.
It evaporates less at high temperatures than ester oils or poly-α-olefin oils, and has excellent oxidation stability and produces less sludge. In addition, greases with terminal aromatics and diurea compounds mainly consisting of terminal aromatics as thickeners not only exhibit good heat resistance and oxidation stability characteristic of urea greases, but also exhibit good shear stability and adhesion. It was confirmed that there was little leakage from the bearings.

The grease composition of the present invention uses a base oil containing alkyldiphenyl ether as an essential component, which has excellent heat resistance and oxidation stability, and the thickener has a terminal aromatic substance that has excellent heat resistance, oxidation stability, shear stability, and adhesion. By using a diurea compound mainly consisting of group and terminal aromatics, it is possible to have a long life at high temperatures.

(Example) Hereinafter, the present invention will be specifically explained with reference to Examples.

In each of the Examples and Comparative Examples, greases were manufactured based on the ingredients shown in Tables 1 and 2, and their physical properties were evaluated by the methods shown below.

(a) Consistency: Based on JIS K 2220.

(b) Shell roll with 10% water content...ASTM D 1
831, 80°C x 168hr test was conducted for 25 hours.
1/4 worked penetration at °C (JIS 2220)
Measure.

This time, we added 10% water to the grease as a promotion condition.
We conducted a test.

(c) Bearing lubrication life...AST)'l D 1741
The test was conducted at 180°C according to the following. In addition, the weight of the bearing before and after the test was measured, and the remaining amount of grease was calculated using the following formula.

Half of the base oil shown in Table 1 and the entire amount of monoamine were placed in a reaction vessel and heated to 70 to 80°C. In a separate container, half of the base oil and the entire amount of diisocyanate were heated to 70 to 80°C, and this was added to the reaction container and stirred. Due to the exothermic reaction, the temperature of the reactant will rise, but continue stirring in this state for about 30 minutes, and after the reaction has sufficiently occurred, the temperature will rise to 175-185°.
It was held at C for 30 minutes and cooled. This was kneaded in a three-roll mill to obtain the desired grease.

In the reaction vessel, base oil 156. The entire amounts of Og and octadecylamine were taken and heated to 70-80'C. In a separate container, base oil 156. Og and tolylene diisocyanate 21.2 g
The mixture was heated to 70-80°C, added to a reaction vessel, and stirred. After continuing to stir for about 30 minutes, the mixture was heated to 180 to 200°C and completely dissolved, so it was immediately cooled and kneaded in a three-roll mill. 400 g of the grease obtained in this way and 1600 g of the grease obtained in Example 3
g were uniformly mixed and kneaded using a three-roll mill to obtain the desired grease.

This negative praise 11 2 4 The target grease was obtained by the same method as in Examples 1 to 5, but using the ingredients shown in Table 2.

780.0 g of base oil and the entire amount of octadecylamine were placed in a main reaction vessel and heated to 70 to 80°C. In a separate container, 780.0 g of base oil and 106.0 g of tolylene diisocyanate.
0 g was taken, heated to 70-80°C, added to the reaction vessel, and stirred. After continuing to stir for about 30 minutes, the temperature is raised to 180-200''C, and the mixture is completely dissolved.
Cooled immediately. This was kneaded in a three-roll mill to obtain the desired grease.

The alkyldiphenyl ether oils shown in Examples and Comparative Examples have a kinematic viscosity of 123.0 cSt at 40°C.
, a synthetic oil with a viscosity index of 125 and a flash point of 284°C, and a pentaerythritol ester oil at 40°C.
The base oil was a synthetic oil having a kinematic viscosity of 29.6 cSt, a viscosity index of 124, and a flash point of 254°C. The tolylene diisocyanate used was a commercially available product containing 2,4-tolylene diisocyanate and 2,6-tolylene diisocyanate in a ratio of 8:2.

Comparing the Examples and Comparative Examples in terms of shear stability, those in which the terminal group of the diurea compound as a thickener is mainly aromatic, that is, Examples 1 to 6 and Comparative Example 4 are good. In addition, the remaining amount in the bearing lubrication life test (180'C) was good in all Examples. In the comparative examples, the heat resistance of the thickener was insufficient, and some thickeners leaked out of the bearing due to softening due to heat (Comparative Example 1.3), while others were observed to fall out of the bearing due to extreme channeling (Comparative Example 1.3). Comparative Example 2) was observed. These phenomena are also noticeable in the lubrication life time. Comparative Example 4 had good shear stability and adhesion because the thickener was a terminal aromatic diurea compound, but evaporation and oxidation of the base oil were large and the life was shorter than that of the example.

(Effects of the Invention) As is clear from the above description, the grease composition of the present invention has a specific amount of a specific diurea compound blended into a base oil containing alkyldiphenyl ether oil as an essential component.
It has low evaporation and oxidation under high temperatures, has excellent shear stability and adhesion, and has a long life.

Claims (1)

[Claims] 1. The base oil containing alkyldiphenyl ether oil as an essential component has the following general formula ▲mathematical formula, chemical formula, table, etc. as a thickener▼...(1) (R_2 in the formula an aromatic hydrocarbon group having 6 to 15 carbon atoms; R_1 and R_3 represent an aromatic hydrocarbon group having 6 to 12 carbon atoms or a linear alkyl group having 8 to 20 carbon atoms;
A grease having a long life at high temperatures, characterized by containing 2 to 35% by weight of a diurea compound represented by R_1 and R_3, in which the ratio of aromatic hydrocarbon groups is 50 to 100 mol%. Composition.