JPH03243696A - Low-noise urea grease composition - Google Patents

Abstract

PURPOSE:To provide the title composition excellent in low-noise performance, heat resistance and durability compared to the conventional low-noise lithium soap grease, comprising a specific urea compound and a base oil at a specified proportion. CONSTITUTION:The objective composition comprising (A) 2 -40wt.% of a urea compound of the formula [R1 and R3 are each mixture of 8-18C alkyl and 5-95 (pref. 20-70)mol% of oleyl; R2 is 3,3'-dimethyl-4,4'biphenylene] and (B) 98 - 60 wt.% of a base oil consisting of alpha-olefin oligomer, paraffin mineral oil, dimethyl silicone, pentaerythritol tetraester etc.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a diurea grease composition used in bearings that require low noise.

[Conventional technology and its problems] Due to recent technological developments and users' preference for luxury products, it has become a challenge to improve the inherent functionality of home appliances, OA equipment, and even automobile parts, as well as reduce harsh noise. ing.

One of the sources of noise in such equipment is bearings that support the rotating shafts of rotating devices such as motors.

The noise generated from this bearing, together with the noise generated from other parts, raises the overall noise level of the device. Causes of this bearing noise include problems with bearing machining and assembly accuracy, mounting accuracy, and the effects of foreign matter and thickener particles in the grease used as a lubricant, but in recent years, this has become a problem. is the noise caused by lubricating grease. In other words, when foreign matter or thickener particles in the lubricating grease that have entered the tiny gap between the rolling elements and the raceway of the bearing break or collapse, they cause the bearing to vibrate, which manifests itself as bearing noise.

Lithium soap grease, which is manufactured through a strictly controlled manufacturing process to prevent foreign matter from entering, is widely used in bearings that require low noise, but due to harsher usage conditions in recent years, it is not stable for long periods of time even at high temperatures. There is a growing demand for grease that exhibits excellent performance.

In response to these demands, attempts have been made to use urea grease, which has a gel structure that is more stable at high temperatures than lithium soap grease, but urea grease has problems with bearing noise due to the nature of its thickener particles. It is not widely used in bearings that require low noise.

The present inventors first analyzed commercially available urea grease in order to investigate the cause of bearing noise caused by urea grease. ) is about 1104L at most, and most of them are less than 5ヰ■, but the unit particles are 20 to 200
There were many aggregates of about 4 m in length, and it was determined that these aggregates were the cause of the bearing noise.

In addition, for each of the combinations of amines, diisocyanates, and base oils shown below, a formulation was created such that the weight ratio of the urea compound produced by the reaction of the amine and diisocyanate to the base oil was 10:90, and the amine group The oil solution and the diincyanate base oil solution are mixed and reacted, and 170
A prototype was prepared and analyzed using a common method of heating and stirring to ℃, cooling to room temperature, and finishing with a Miki roll mill.

Amines n-propylamine, isopropylamine n-butylamine isobutylamine S-butylamine
n-pentylamine 3-methylbutylamine, n-hebutylamine n-octylamine, 2-ethylhexylamine n-dodecylamine, n-tetradecylamine n-hexadecylamine, n-octadecylamine aniline 4-biphenylamine p- Phenetidine, p-7 nisidine p-dodecylaniline, cyclopentylamine cyclohexylamine.

Dihydroabiethylamine.

3.5.5-) Limethylhexylamine.

Oleylamine diisocyanates 1.5-Naphthylene diisocyanate 4.4'-Diphenylmethane diisocyanate 2.4-
Tolylene diisocyanate 3.3'-dimethyl-4
, 4'-biphenylene diisocyanate hexamethylene diisocyanate base oil α-olefin oligomer (40°C kinematic viscosity 30 cSt)
Paraffinic mineral oil (Kinematic viscosity at 00°C, 67 cSt) Dimethyl silicone (Kinematic viscosity at 25°C, 200 cSt) Pentaerythritol tetraester (Kinematic viscosity at 40°C, 31 cSt) Analysis results show that oleylamine and 3.3'-dimethyl-4
, 2 in all prototype greases except for the grease in which 4'-biphenylene diisocyanate was reacted in the base oil.
0-200. It was confirmed that there were many aggregates of Peng size.

Among the samples containing about 20 to 200 aggregates,
n-octylamine and 4,4'-diphenylmethane diisocyanate were dissolved in paraffinic mineral oil (40°C kinematic viscosity 67c).
Grease, cyclohexylamine and 4,4'-diphenylmethane diisocyanate reacted in pentaerythritol tetraester (40℃ kinematic viscosity 31c
As a result of trying to further pass the grease reacted in St) through a three-roll mill, it was confirmed that the grease was reduced by about 50% after passing through it 20 times. However, even after 100 passes, a slight decrease is observed, but it does not disappear completely. In addition, such a method requires excessive time and labor, and is difficult to use in practical use. Homogenizer treatment, ball mill treatment, and colloid mill treatment were tried as methods, but no significant effects were obtained.As mentioned above, it is thought that once aggregates are formed, there is a limit to mechanical treatment. Ta.

Grease made by reacting oleylamine with no aggregates and 3,3'-dimethyl-4,4'-biphenylene diinocyanate in base oil has excellent low noise performance, but does not remain quiet for a long time. For example, grease based on mineral oil (thickener content: 20% by weight) has a
The mixing consistency (JIS K 22205.3) was 2 in 0 days.
71 to 328, showing a tendency to soften considerably, and dropping point test (JIS K 22205
．． In 4), it drips at temperatures below 180°C, and in reality it can only be used at temperatures below 150°C.In other words, greases using this thickener have poor storage stability and stability compared to other urea greases. There was a problem that high temperature stability was poor.

[Means for Solving the Problem] Therefore, the present inventors have proposed a method that impairs the excellent low-noise performance of a grease prepared by reacting oleylamine and 3,3'-dimethyl-4,4'-biphenylene diisocyanate in a base oil. As a result of extensive research into thickeners that have excellent storage stability and high-temperature stability, we have discovered a thickener represented by the following general formula.

General Formula % Formula % [In the formula, R1 and R3 are a mixture of an alkyl group having 8 to 18 carbon atoms and an oleyl group, and the proportion of the oleyl group is 5 to 95 mol%. In addition, R2 represents a 3,3'-dimethyl-4,4'-biphenylene group.] In this formula, R
If 1 and R3 contain an alkyl group, a phenyl group, or a cycloalkyl group having 7 or less carbon atoms, aggregates of the thickener will be formed, which is not suitable for the present invention. 1 carbon number in R1 and R3
If it contains more than 8 alkyl groups, it is difficult to obtain a long-chain monoamine as a raw material at an economical price, so it is not suitable for practical use.In addition, the proportion of oleyl groups in R1 and R3 is ~95 mol% preferably 20-7
If it is less than 5 mol%, aggregates of the thickener will grow, and if it exceeds 95 mol%, storage stability and high temperature stability will be poor, and both are not suitable for the present invention.

That is, the urea grease composition consisting of the thickener and base oil represented by the above general formula has excellent low noise performance and can be stored for 60 days with a change in mixing consistency of ±1O or less. It has stability and high temperature stability with a dropping point of 190°C or higher.

As a result of further research, R1 and R3 of the above general formula
By separately manufacturing two or more types of grease with different alkyl groups and mixing them, a grease with a higher perfect score than any of the greases before mixing and a gel structure that is stable even at high temperatures can be obtained. I found something that can be done. As for the mixing ratio of the two types of grease, an increase in the dropping point is observed even when the weight ratio of the thickener of the two types of grease is 1:S9. In order to achieve this, a mixing ratio such that the weight ratio of different thickeners is 10-90 to 90-10 is desirable.

By the method described above, we have completed an extremely useful urea grease that has the high temperature stability characteristic of urea grease and also has lower noise performance that is superior to lithium soap grease.

The urea grease described in claim 1 of the present invention can be produced by mixing base oil solutions of all amines and all diisocyanates at 80 to 120°C, and mixing them at a rate of 1 to 5°C per minute while stirring. The temperature is raised to 170-200℃, left to cool, and then finished with a three-roll mill.
It can be obtained by a known general manufacturing method. Furthermore, the method for mixing two or more types of greases containing different alkyl groups in their thickeners as set forth in claim 2 of the present invention can be carried out as long as the greases are uniformly and well mixed. The apparatus is not particularly limited, but in order to obtain the grease of the present invention having a stable gel structure even at high temperatures, it is necessary to mix the greases.

Even if two or more different types of alkylamines are mixed during the reaction of diincyanate and amine, the desired urea grease cannot be obtained.

The base oils used in the present invention are generally known lubricating oils, such as mineral oil, α-olefin oligomer silicone oil, diester oil, triester oil, tetraester oil, fluorine oil, phosphate ester oil, castor oil, and phenyl ether oil. Al with oil, alkylnaphthalene, alkylene glycol, etc.

In the diurea grease composition of the present invention, the content of the diurea compound as a thickener is 2 to 40% by weight, preferably 5 to 35% by weight. Diurea compound content is 2
When the weight percent is not swirled, the thickening effect is small and the grease does not form.If it exceeds 40 weight percent, the grease becomes too hard and a sufficient lubricating effect cannot be obtained.

In addition to the original ingredients, various additives such as antioxidants, rust preventives, and extreme pressure agents are added to the diurea grease of the present invention in order to further improve its performance without impairing its intended properties. I can do things.

[Effect] The effect of the present invention is generally considered to be as follows, but the detailed mechanism has not yet been elucidated.

The diurea grease of the present invention is first characterized in that an oleyl group and an alkyl group having 8 to 18 carbon atoms are appropriately mixed in the thickener. This method improved the storage stability and high temperature stability of a grease obtained by reacting oleylamine and 3,3'-dimethyl-4,4'-biphenylene diisocyanate in a base oil. This has a cis structure in which the hydrocarbon group is on the same side as the double bond, and the oleyl group, or cis-8-octadecenyl group, has a largely bent three-dimensional structure in the center of the carbon chain in the diurea molecule. Because of its 3D structure, it is difficult to form thickener particle aggregates, but it is thought that the instability as a thickener due to its 3D structure was alleviated by mixing an appropriate amount of alkyl groups. .

Furthermore, the second feature is that two or more types of greases containing different alkyl groups as thickeners are mixed among the greases obtained by the above method. This blend further improved high temperature stability. The reason why the dropping point increases by mixing in this way is thought to be that particles with different properties, ie, particles with different alkyl groups in the thickener, mutually reinforce the gel structure.

Generally, when a solution in which two or more types of monoamines are uniformly dispersed is added to a diincyanate solution and reacted, three or more types of diurea compounds are generated depending on the difference in the amine residues bonded to both ends. The proportion depends on the reactivity of the monoamine used and the mixing ratio. However, these diurea compound molecules do not form separate particles for each type in grease, but are mixed together in a complex manner, and although the individual particles may differ slightly from each other, they are similar. It is thought that the particles have certain properties. Therefore, even if two or more different types of alkylamines are mixed during the reaction of diisocyanate and monoamine, thickener particles with different properties can mutually reinforce the gel structure. The diurea grease described in claim 2 of the invention cannot be obtained.

[Example] The present invention will be specifically explained by the following Examples and Comparative Examples. The abbreviations, terms, and test methods used in Examples and Comparative Examples are as follows.

■TO[] I 3.3-dimethyl-4,4'-biphenylene diinocyanate ■Mineral oil Paraffin-based refined mineral oil 40°C kinematic viscosity 87 cSt ■α-
Olefin α-olefin oligomer 40℃ kinematic viscosity 30cSt■
Phenyl ether alkyl diphenyl ether Kinematic viscosity at 40℃ 87cSt■
Oleyl/non-oleyl ratio Indicates the molar ratio between the oleyl groups and other hydrocarbon groups (non-oleyl groups) of both terminal groups of all diurea compounds in the grease. For example, oleyl group is 30 mol%, non-oleyl group is If it is 10 mol%, it is expressed as 90/10.

■Mixing consistency According to JIS K 22205.3.

■Full score According to JIS K 22205.4.

■Storage Stability Approximately 500 g of grease is stored in a sealed container at 25±3°C for 60 days, then the mixing consistency is measured, and the difference in consistency from before the test is calculated using the following formula.

Difference in consistency = Mixing consistency after 60 days - Mixing consistency before the test ■ Number of aggregates Applying the dirt test (JIS K 22205.9), apply grease to a slide glass, cover it with a cover glass, and create a grease film. The thickness was set to 30 pm, and an optical m-microscope (
Observed at 100x magnification), 0.46mw x 0.64mm
Count the aggregates with a size of 20 L or more within the frame.

・Anzolone value of 1 Anzolone meter is widely used as a vibration measuring device for rolling bearings, and is a device that rotates the inner ring of the bearing and indicates the vibration of the outer ring that is loaded with a thrust load in units of anzolone.0 This invention So, bearing 6200, grease filling amount 0.30g, bearing inner ring rotation speed 180Or, p
, m, the bearing was rotated for 1 minute under the condition of thrust load 2.0 kg, and after 1 minute the old ghBand (1800"
100OOH2) is read as the anzolone value.

The table shows the formulation and test results of each grease of Examples and Comparative Examples. The manufacturing method of each grease is as follows.

Examples 1 to 12) Comparative Examples 1 to 6 With the formulation shown in the table, 80% total diisocyanate was added to the base oil topical amount.
Add all amines to the solution heated and dissolved at 80°C and the remaining base oil.
The heated and dissolved solution was mixed and stirred well for 20 minutes.

The mixture was stirred at an average rate of 2°C per minute at 190°C.
The temperature was raised to ℃. After cooling to around room temperature, each grease was passed through a three-roll mill twice to obtain each grease.

Examples 13 to 15 The greases obtained in Example 2 and Example 8 were mixed in the formulation shown in the table and passed through a three-roll mill twice to obtain each grease.

Example 16 Example 2) The grease obtained in Example 6 and Example 8 was
They were mixed at a weight ratio of 40:30:30, respectively, and passed through a three-roll mill twice to obtain a grease.

Comparative Examples 7 to IO A commercially available urea grease and a commercially available low-noise lithium soap grease.

From Examples 1 to 12, it is clear that the thickener contains an oleyl group and a carbon number of 8.
It can be seen that the storage stability and high-temperature stability of the grease of Comparative Example 1 were improved without impairing the low-noise performance of the grease of Comparative Example 1 by appropriately mixing the alkyl groups of 1 to 18.

The greases of Examples 1 to 12 had the same level of drop density as commercially available low-noise lithium soap greases, but there were no aggregates larger than 20 mm, and the anzolone value was 11.5 to 1.
3.5, and it is clear that it has superior low-noise performance to the commercially available urea greases and commercially available low-noise lithium soap greases shown in Comparative Examples 7 to 10.

The greases of Example 11 and Example 12 have different alkyl groups in the thickener, but two different types of alkyl amines were added during the reaction with the diisocyanate.
Since it is not a mixture of greases, it does not have a high dropping point.

Examples 13 to 16 are mixtures of two or more types of greases according to claim 1 of the present invention having different alkyl groups in their thickeners, and all of the greases were recognized to have a perfect score. In particular, Examples 14 to 16 are extremely useful greases that have excellent high-temperature stability, which is a characteristic of urea greases, and low-noise performance that is superior to commercially available low-noise lithium soap greases.

The grease of Comparative Example 1 has excellent low noise performance, but
Since there is no appropriate amount of alkyl groups, the high temperature stability and storage stability are inferior to the grease of the present invention.

Since the greases of Comparative Examples 2 to 5 contain an alkyl group having 7 or less carbon atoms, a cycloalkyl group, or a phenyl group in the thickener, aggregates of the thickener are formed and the desired low noise performance is not achieved. does not have.

In Comparative Example 6, since the oleyl group in the thickener was less than 5 mol %, aggregates of the thickener were present and the desired low noise performance was not achieved.

(Effects of the Invention) The low-noise urea grease composition according to the present invention is a dispersion system of fine diurea compound crystals free of aggregates of 20 iL or more of diurea compound particles as a thickener, and is different from the conventional one. It is possible to manufacture by a similar concentrating method.

The obtained diurea grease composition was confirmed to have low noise performance and high temperature stability superior to commercially available low noise lithium soap greases.

That is, the present invention has the effect of providing a low-noise urea grease that has better heat resistance and durability than conventional low-noise lithium soap grease.

Claims (2)

[Claims] (1) General formula R1-NHCONH-R2-NHCONH-R3 [wherein R1 and R3 are a mixture of an alkyl group having 8 to 18 carbon atoms and an oleyl group, and the ratio of oleyl groups is 5 to 9
5 mol%, and R2 is 3,3'-dimethyl-4,
Represents a 4'-biphenylene group. A low-noise urea grease composition comprising 2 to 40% by weight of a urea compound represented by the following formula and 98 to 60% by weight of a base oil. (2) 2 of the grease composition according to claim 1
A low-noise urea grease composition that is a mixture of more than one type and maintains a stable grease structure even at high temperatures.