JPH02208396A - Diurea grease composition having improved acoustic property - Google Patents

Abstract

PURPOSE:To obtain the title composition excellent in heat stability and shear stability by incorporating a specified amount of a thickening agent containing a plurality of specified diurea compounds into a base oil comprising a mineral oil or synthetic oil. CONSTITUTION:A base oil comprising a mineral oil or synthetic oil is mixed with 2-35wt.% thickening agent containing diurea compounds respectively of the formula R1NHCONHR2NHCONHR3 and of the formula R1NHCONHR4 NHCONHR3 [wherein R1 is 12-22C straight-chain (un)saturated alkyl; R2 is tolylene or xylylene; R3 is an alkyl or halogen-substituted aromatic group; R4 is bitolylene].

Description

[Detailed description of the invention] a. OBJECTS OF THE INVENTION INDUSTRIAL FIELD OF APPLICATION The present invention relates to urea greases with improved acoustic properties.

Conventional Waves and Problems to be Solved In general, urea grease has a higher dropping point, is thermally stable, and has a longer service life than greases that use lithium soap as a thickener.
In recent years, urea grease has come to be widely used as a heat-resistant grease, and the required performance has diversified as the applications for urea grease have expanded.

For example, lithium-based grease is mostly used in places where acoustic characteristics are important, but as the demands for smaller, lighter weight, precision, lower noise, and longer life of machines increase year by year, bearings are also becoming smaller. Due to the high speed rotation and the high density of parts, the temperature rises, creating a very harsh lubrication environment. It is becoming difficult to use lithium-based grease to deal with this situation.

On the other hand, urea-based greases have excellent thermal stability and are used in areas subject to high temperatures like heat-resistant greases (clay-based, Combresox soap-based, sodium-terephthalate-based, etc.), but their acoustic properties are extremely poor. It is unsuitable for bearings where acoustic characteristics are important.

In general, bearing acoustics refers to vibrations generated on the sliding surface between the bearing's holes or rollers and races, or the sliding surface between the retainers, which is detected as sound.

This vibration includes not only the vibration of the bearing itself but also the vibration caused by dust entering from the outside and solid foreign matter in the grease intervening on the bearing sliding surface.

The thickener in grease is also a solid foreign substance, and like dirt and flakes, the form and type of the thickener affect the acoustic characteristics of the grease. For example, lithium soap-based grease can be produced relatively easily by saponifying fats and oils or fatty acids with lithium hydroxide, then melting the soap, and cooling and other treatments to make the lithium soap fibers small and fine. Grease can be made.

Further, urea grease is a grease containing a urea compound produced by a reaction between an amine and an isocyanate as a thickener. The urea compound obtained by this reaction is often dispersed as large particles in the oil and has poor acoustic properties. Although the acoustic properties can be improved by a treatment method that reduces the size of the particles, this method is not preferred because it is extremely uneconomical.

In the conventional technology, succinic acid is used during thickener production as disclosed in JP-A-58-18593 (diurea-based grease and its manufacturing method) and JP-B-62-44039 (high dropping point lithium complex grease composition). Another method is to add additives such as imides or metal salt detergents to improve the acoustic properties by finely and uniformly dispersing the thickener. However, in the case of urea grease, the effect is small and it is difficult to improve the acoustic characteristics.

Means for Solving the Constituent Problems of the D0 Invention The inventors of the present invention conducted research to overcome the drawback of poor acoustic properties of conventional urea grease compositions.
Isocyanes are raw materials for thickeners in urea grease.
It has been discovered that diurea grease with extremely excellent acoustic properties and shear stability can be obtained by changing the type or combination of 1. and amines.

That is, the present invention is based on the formula % (wherein R+ is a linear saturated alkyl group or a linear unsaturated alkyl group having 12 to 22 carbon atoms, R2 is an l-IJ lene group or a xylylene group, and R3 is an alkyl-substituted aromatic group). or a halogen-substituted aromatic group, and R4 represents bi-1-lylene group. This patent is characterized by containing %.

In the diurea compound used as a thickener, (8) by reaction between an isocyanate having a tolylene group, a xylylene group, or a bitrylene group and an amine having a linear saturated alkyl group or a linear unsaturated alkyl group having 12 to 22 carbon atoms. Although the diurea compound produced improves acoustic properties, the resulting grease often has a low perfect score of 200°C or less, and has poor shear stability.

(B) A diurea compound produced by the reaction of an isocyanate having an l-lylene group, a xylylene group, or a bitrylene group with an amine having an alkyl-substituted aromatic group or a halogen-substituted aromatic group improves the perfect score to 250°C or higher. , the acoustic properties and shear stability of the resulting grease are poor.

(C) Isocyanate having l-lylene group or xylylene group and bitrylene group, amine having linear saturated alkyl group or linear unsaturated alkyl group having 12 to 22 carbon atoms, and alkyl-substituted aromatic group or halogen-substituted aromatic group Diurea compounds produced by reacting with amines have high dropping points and provide greases with excellent acoustic properties and stability.

(1)) The Shiralea compound produced by reacting the diisocyanate described in item (C) above with an amine having a linear saturated alkyl group or a linear unsaturated alkyl group having 12 to 22 carbon atoms has a perfect score of 200. Provide grease with low shear stability, below °C.

(E) The sirarea compound produced by reacting only the diisocyanate-1- described in item (C) with an alkyl-substituted aromatic group or a halogen-substituted aromatic group provides a grease with poor acoustic properties and shear stability.

(F) The siralea compound produced by reacting the above amine with an isocyanate having a diphenylmethane group instead of the bitrylene group contained in the diisocyanate-1 described in item (C) above is a grease with poor acoustic properties and shear stability. give. In particular, the resulting grease has poor shear stability at high temperatures.

(G) Isocyanate described in the preceding section (C) and carbon number 12
Silarea compounds produced by reacting only amines having linear saturated alkyl groups or linear unsaturated alkyl groups shown below improve the dropping point of greases, but give greases with poor acoustic properties and shear stability.

The amount of the thickener used in the present invention, mineral oil or synthetic oil, to be blended in the base oil is 2 to 35% by weight, preferably 5 to 20% by weight, based on the base oil.

If the amount of thickener added is less than 2% by weight, the consistency will decrease.
2 is not sufficient, and on the other hand, if it exceeds 35% by weight, the grease becomes too hard. Especially thickener 5 to 20
When blended in weight percent, a grease with extremely excellent performance can be obtained.

In order to further improve the performance of the grease of the present invention, various additives such as antioxidants, extreme pressure agents, and anti-wear agents can be added.

Next, the present invention will be described in detail with reference to examples, but the present invention is not limited thereto.

Examples 1 to 9, Comparative Examples 1 to 11 2.4/2.6-1-lylene diisocyanate (2,4/2.6 mixing ratio 80-tχ
/20%) or metaxylylene diisocyanate or 3,3'-bitricin-4,4'-diisocyanate or diphenylmethane 4,4'-diisocyanate and 60% by weight of the total amount of base oil as a grease. After putting it in a pot and heating it to about 70°C to dissolve the diisocyanate,
A linear alkylamine or an aromatic amine dissolved in 40% by weight of residual oil was gradually added and vigorously stirred. Although the temperature rose due to the reaction between diisocyanate and amine, 3
After stirring in this state for 0 minutes, the reaction was completed by heating to 120°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 Examples and Comparative Examples is 11 cst (
100℃), polyol ester oil was 7 cst (10
0'C). Grease consistency of each example and comparative example, perfect score, shell roll (room temperature and 150°C
824h) and the results of the acoustic test are shown in Table 1.

In Table 1, Comparative Examples 1 to 8 have an isocyanate component (
al and (bl, linear saturated aliphatic amine or unlinear unsaturated aliphatic amine, aromatic amine, or halogen-substituted aromatic amine) grease properties (acoustic properties,
The purpose of this test was to investigate the effect on the shear stability (full score, shear stability).

From Example 1 and Comparative Example 8, the diurea compound is the component (a).
It was found that when the component (bl) is contained, a sharper acoustic characteristic can be obtained than when the component (a) is contained alone. Also, from Example 1 and Comparative Example 9, diurea compounds other than the component (b) can be obtained. (diphenylmethane-4,4' diisocyanate) was found to have poor acoustic properties.

Further, from Example 1 and Comparative Example 11, it was found that using a linear aliphatic amine alone cannot sufficiently improve both the dropping point and the acoustic properties.

Furthermore, from Comparative Examples 10 and 11, when a linear saturated alkylamine having 12 or less carbon atoms is used instead of a linear saturated alkylamine having 12 or more carbon atoms, a grease with significantly inferior acoustic properties can be provided. Understood.

In Examples 1 to 9, a grease property test was conducted using a grease containing a diurea compound containing components (a) and (bl), a linear saturated (unsaturated) alkylamine, and an aromatic (halogen-substituted aromatic) amine. I did it.

As a result, it was found that the acoustic properties, dropping point, and shear stability were different from those of the greases of Comparative Examples 1 to 11.

Example 10 Grease was prepared by adding additives such as an antioxidant and a rust preventive to the grease of Example 1. A performance test was conducted comparing this with commercially available grease, and the results are shown in Table 2.

From Table 2, it was found that the grease of the present invention had a high dropping point and its acoustic properties were significantly superior to commercially available products.

Effects of the Invention The diurea grease of the present invention not only has good thermal stability, which is a characteristic of urea grease, but also has good shear stability from room temperature to high temperature. It is an extremely excellent urea grease that has a stable structure and good acoustic properties, which were the drawbacks of urea grease.

Consistency: JIS K 2220 Drop Point: JIS K 2220 Shellrono I) A! 1. : AsTM D 183'
Acoustic test: Measured by the method described in Japanese Patent Publication No. 53-2357.

Agent: Patent Attorney 1) Osamu Sumi Procedural amendment December 22, 1999

Claims (1)

[Claims] Formula (a) R_1NHCONHR_2NHCONHR_3(
b) R_1NHCONHR_4NHCONHR_3 (wherein R_1 is a linear saturated alkyl group or linear unsaturated alkyl group having 12 to 22 carbon atoms, R_2 is a tolylene group or xylylene group, R_3 is an alkyl-substituted aromatic group or a halogen-substituted aromatic group, R_4 represents a bitrylene group) An acoustic property characterized by containing a thickener containing diurea compounds (a) and (b) represented by 2 to 35% by weight based on the base oil, which is mineral oil or synthetic oil. A diurea grease composition with improved