JPH0277494A - Urea grease composition improved in acoustic performance - Google Patents

Abstract

PURPOSE:To provide the title composition excellent in thermal stability and shear stability, small in softening tendency, improved in acoustic effect, containing each specific two kinds of diurea compound at specified ratio. CONSTITUTION:The objective composition comprising (A) 90-20mol% of a compound of formula I (R1 and R3 are each 1-18C alkyl; R2 is bitolylene) and (B) 20-90mol% of a second compound of formula II (R4 and R6 are each 8C-saturated alkyl; R5 is diphenylmethane). The preferable amount of this composition to be incorporated is 5-20 pts.wt. based on 100 pts.wt. of a mineral oil or synthetic oil.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to urea grease compositions with particularly improved acoustic performance.

(Problems to be solved by the prior art and the invention) In general, urea grease has a higher dropping point than grease using lithium soap as a thickener, is thermally stable, and can be used at high temperatures for long periods of time, so it is heat resistant. It came to be used in a wide range of places as a grease. However, although the performance of urea grease has improved year by year, its track record is limited, and there are many points that need to be improved depending on the application. For example, when looking at acoustic performance, most commercially available urea greases have extremely poor acoustic performance and cannot be used at all in areas where acoustic performance is important. Therefore, most of the greases that are said to be for low-acoustic applications are lithium soap-based greases. However, as the demands for machines to be smaller, lighter, more precise, lower noise, and have longer lifespan have grown year by year, the bearings used in these rotating parts have naturally become smaller, faster, and rotated at higher speeds, and the number of parts has increased. Because of this concentration, the temperature also rises, making the lubrication environment extremely difficult. A number of greases have been studied to deal with these situations, but there are almost no greases that satisfy all requirements in terms of performance. For example, many lithium soap-based greases, which are widely used as general-purpose greases, have relatively good acoustic performance, and most bearings that place emphasis on acoustic performance use lithium soap-based greases. However, compared to heat-resistant greases (urea-based, clay-based, complex soap-based, sodium-terephthalamate-based, etc.), it has a lower operating temperature limit and can hardly be used in areas subject to high temperatures.

On the other hand, urea-based grease has excellent thermal stability,
Although it is preferred for use in areas subject to high temperatures, its acoustic performance is very poor, making it unsuitable for bearings where acoustic performance is important.

In general, the grease lubrication mechanism for bearings is such that the grease packed inside the bearing is temporarily blown away by rotation, and then undergoes repeated churning and channeling until it reaches a
Grease or oil of Wl and it is supplied to the sliding surfaces to lubricate them. Acoustics detects the vibrations generated on this sliding surface (between the ball or roller and the race surface or retainer) as sound, but this vibration is caused by mechanical vibrations caused by unevenness or play on the sliding surface. There are vibrations generated by the bearing itself, and vibrations generated by dust and dirt mixed in from the outside, as well as solid foreign matter contained in grease, intervening on the bearing sliding surface.

Solid foreign matter contained in grease is so-called external dirt, dust, etc., but the thickener in grease is also a solid foreign matter, and the acoustic performance depends on the form and type of this thickener. Different.

For example, lithium soap-based grease has a three-dimensional fibrous structure and gels through a saponification reaction between lithium hydroxide and oils, fats, or fatty acids, but the fibers themselves are soft and the cooling method and other factors Through processing, it is possible to make the fibers smaller and finer, making it relatively easy to create a grease with good acoustic performance. In addition, urea grease is generally a grease that contains a compound formed by the reaction of amine and isocyanate as a thickener, but most of the urea compounds obtained through this reaction are hard, granular particles, and these are dissolved in the oil. It is dispersed and maintains a grease state. If the granular particles are large, the acoustic performance will naturally deteriorate, so making the particles finer will improve the acoustic performance to some extent, but it will not be a fundamental improvement. Some urea greases retain their fibrous structure, while others have thickener particles that soften and have good acoustic performance. Many greases harden.

Conventional techniques include JP-A-58-18593 (diurea-based grease and its manufacturing method) and JP-A-62-44039.
(High Dropping Point Lithium Complex Grease Compositions), where additives such as succinimide or metal salt detergents are used to improve acoustic performance by uniformly dispersing the thickener. There are many. However, especially in the case of grease grease, the effect of these additives is small for the reasons mentioned above, and the essential acoustic performance can hardly be improved. It has been difficult to produce grease with good acoustic performance, mechanical stability and heat resistance, and there has been a tendency to ignore acoustic performance.

By changing the type or combination of isocyanates and amines used as raw materials for thickeners, a wide variety of urea greases can be made, and the performance of these greases is also wide-ranging. Become.

(Means for Solving the Problem) The inventors of the present application have conducted intensive research to overcome the drawback of poor acoustic performance of conventional urea grease compositions, and as a result, have produced a number of prototype urea greases that have excellent acoustic performance. We have found that when diurea compounds with particularly excellent properties are selected and the diurea compounds are mixed in a specific proportion, a grease with extremely excellent acoustic performance and shear stability can be obtained. That is, it has been discovered that a grease containing a thickener mixed with a limited diurea compound in a specific ratio has excellent acoustic performance and shear stability.

That is, the present invention provides a grease thickener characterized by containing 90 to 20 mol% of a compound represented by the following general formula +a) and 20 to 90 mol% of a compound represented by the following general formula (b), and a grease thickener characterized by containing a compound represented by the following general formula ( It is characterized by consisting of 100 parts by weight of a mixture containing 90 to 20 mol% of a compound of al and 20 to 90 mol% of a compound of the following general formula (bl), and 5 to 90 parts of a compound (c) of the following general formula: and 2 to 3 parts of the grease thickener according to claim 1 or 2 per 100 parts by weight of mineral oil or synthetic oil.
This is a urea grease composition characterized in that it contains 0 parts by weight.

General formula % Formula % Preferably, when the above-mentioned thickener is contained in 5 to 20 parts by weight per 100 parts by weight of mineral oil or synthetic oil, a grease with extremely excellent performance can be obtained.

In the diurea mixture of (a) and (b), (b)
If the proportion of the compound is less than 20 mol %, the effect of mixed use will be small, and if it exceeds 90 mol %, the acoustic performance will not improve. When 5 to 90 parts by weight of the compound (b) is mixed with 5 to 90 parts by weight of the compound (b) (relative to the al compound) (relative to 100 parts by weight of the mixture of al and (b)), the ratio of the compound b) is 20 to 90 mol%. Improved performance and perfect score. When the proportion of the compound (C) is less than 5 parts by weight, the effect of mixing and use is small, and when it exceeds 90 parts by weight, it is not preferable from the viewpoint of consistency.

In the grease according to the present invention, R1 is a bitrylene group, R1
and a diurea compound in which R1 is a linear or branched saturated alkyl group or unsaturated alkyl group having 18 carbon atoms, R3 is a diphenylmethane group, and R4 and R6 are linear or branched linear or branched alkyl groups having 8 carbon atoms. When mixed with a diurea compound which is a saturated alkyl group, or when a diurea compound in which R1 is a tolylene group or a bitrylene group, and R1 and R are an alkyl-substituted aromatic group or a halogen-substituted aromatic group, is added to the above mixture. It is a diurea grease characterized by excellent acoustic performance and shear stability. Even if a diurea compound were prepared by converting R+ to R7 to a compound other than the above, there would be no effect at all in terms of performance. For example, when R and R8 are octadecyl groups and R2 is a diphenylmethane group or tolylene group, the mechanical stability of diurea grease at high temperatures is extremely poor.

In addition, diurea grease containing a thickener in which R4 and R4 have 8 carbon atoms and R1 is a tolylene group or a bitrylene group, or an alkyl group having 10 to 14 carbon atoms can be used.
Diurea grease containing a thickener in which 3 is a tolylene group, a bitrylene group, or a diphenylmethane group has poor mechanical stability at high temperatures. Further, diurea grease containing a thickener in which R1 and R9 are an alkyl-substituted aromatic group or a halogen-substituted aromatic group and R is a diphenylmethane group has very poor acoustic performance.

In the grease according to the present invention, R9 and R1 are, for example, octadecyl groups and R2 is a bitrylene group (a
l compound, and R4 and R6 are, for example, octyl groups and R
6 is represented by a diphenylmethane group (By combining BL compounds in a specific ratio, the mechanical stability at room temperature, which is a drawback when using a fat compound alone, is improved, and the acoustic performance is also improved. Furthermore, in the mixture of (a) and (bl compounds, R1 and R1 are an alkyl-substituted aromatic group or a halogen-substituted aromatic group, and R6
is represented by a tolylene group or a bitlylene group (C
) By adding a compound, it is possible to further improve the dropping point and improve the thermal stability of the grease without impairing the above performance. In order to further improve the performance of this lubricating grease, various additives such as antioxidants, extreme pressure agents, and anti-wear agents may be added.

(Effects of the Invention) The diurea grease of the present invention not only has extremely excellent acoustic performance, but also has excellent thermal stability from room temperature to high temperature.
It has good mechanical stability, with a stable grease structure even when exposed to high temperatures for long periods of time, and has little tendency to harden or soften due to shearing. Moreover, it is an extremely excellent urea grease with little tendency to soften due to lack of shear stability from room temperature to high temperature.

Hereinafter, the present invention will be described in detail with reference to Examples.

3.3'-vitrylene-4,4'-diisocyanate of the compound (a) and 6 of the total amount of base oil at the blending ratio shown in Table 1.
0% by weight of the base oil was placed in a grease pot and heated to approximately 80°C to dissolve the diisocyanate. It was added gradually and stirred vigorously. After about 10 minutes, (
After adding the BL compound diphenylmethane 4,4'-diisocyanate, octylamine dissolved in base oil in an amount of 20% by weight of the total amount of base oil was added and stirring was continued. The temperature rose due to the reaction between the diisocyanate and the amine, but after stirring in this state for about 30 minutes, the reaction was completed by heating to 170°C. Thereafter, the mixture was allowed to cool to room temperature and kneaded to make a grease.

The viscosity of the mineral oil shown in the examples was 11 cst (100°C), and the viscosity of the polyol ester oil was 7 cst (100°C). The consistency of the grease in each example was perfect, shell roll (room temperature and 150°C, 24 hours), The results of the consistency after heating at 150°C (25°C, immiscible) and the acoustic test are shown in Table 1.

Put diisocyanate and mineral oil in an amount of 80% by weight of the total amount of mineral oil into a grease pot at the mixing ratio shown in Table 2 above, heat it to about 80°C to dissolve the diisocyanate, and then add 2% of the total amount of mineral oil.
Amine dissolved in 0% by weight mineral oil was added and stirred. After continuing stirring in this state for about 30 minutes, the mixture was heated to 170° C. to complete the reaction, allowed to cool to room temperature, and kneaded to prepare a grease.

Next, a grease was prepared by mixing the diurea grease of Example 6 and the diurea grease consisting of the compound (C) above.

Grease consistency of each example, perfect score, shell roll (
Table 2 shows the results of the consistency after heating (25°C, immiscible) at room temperature and 150°C for 24 hours, and the acoustic test at 150°C. In addition, a grease was made by adding additives such as antioxidants and rust preventive agents to the grease of Example 10 (Example 21), and a test was conducted comparing it with commercially available urea grease. Indicated.

(Hereinafter #'t3) Table 3 Measurement method Consistency: JIS K2220 Dropping point: JIS K2220 Shell roll: ASTM D1831 150°C hardness after heating: According to JIS K2220, 2-consistency measuring device was filled with grease, 150°C, After heating for 72 hours, it was cooled and the unworked penetration was measured at 25°C.

Acoustic test: Measured by the method described in Japanese Patent Publication No. 53-2357.

Claims (3)

[Claims] (1) A grease thickener characterized by containing 90 to 20 mol% of a compound represented by the following general formula (a) and 20 to 90 mol% of a compound represented by the following general formula (b). General formula (a) R_1NHCONHR_2NHCONHR_3(
b) R_4NHCONHR_5NHCONHR_6 In the above formula, R_2 represents a bitrylene group, and R_1 and R_3 represent a linear or branched saturated or unsaturated alkyl group having 18 carbon atoms. R_5 represents a diphenylmethane group, and R_4 and R_6 represent a linear or branched saturated alkyl group having 8 carbon atoms. (2) 100 parts by weight of a mixture containing 90 to 20 mol% of the compound of the following general formula (a) and 20 to 90 mol% of the compound of the following general formula (b) and (c) of the following general formula
A grease thickener comprising 5 to 90 parts by weight of a compound. General formula (a) R_1NHCONHR_2NHCONHR_3 (b) R_4NHCONHR_5NHCONHR_6 (c) R_7NHCONHR_8NHCONHR_9 In the above formula, R_2 is a bitrylene group, and R_1 and R_3 are a linear or branched saturated alkyl group or an unsaturated alkyl group having 18 carbon atoms. . R_5 represents a diphenylmethane group, and R_4 and R_6 represent a linear or branched saturated alkyl group having 8 carbon atoms. R_8 represents a tolylene group or a bitrylene group, and R_7 and R_9 represent an alkyl-substituted aromatic group or a halogen-substituted aromatic group. (3) 2 to 30 parts of the grease thickener according to claim 1 or 2 per 100 parts by weight of mineral oil or synthetic oil.
A urea grease composition characterized in that it contains parts by weight.