JPH026599A - Lubricant composition - Google Patents

Abstract

PURPOSE:To enable the use under high-temperature and high-shear conditions, by compounding specific diamide-dureas(DADU) as thickening agents, thereby improving heat resistance and mechanical stability. CONSTITUTION:The title lubricant compsn. is prepd. by compounding 25-50wt.% of DADU compds. of the formula R1CONHR2NHCONHR3NHCONHR4NHCOR5 (wherein R1, R5 are 1-22C aliphatic, alicyclic or aromatic hydrocarbon radicals; R2, R4 are 1-8C aliphatic, alicyclic or aromatic hydrocarbon radicals; R3 is an aliphatic, alicyclic or aromatic hydrocarbon radical) with base oils (pref. ester base oils or base oils wherein not less than 1/3 is ester oils). The DADU compd. is obtd. by polyaddition reaction of, e.g., 2mol of N-(4-aminophenyl) acetamide with 1mol of diphenylmethane-4,4'-diisocyanate.

Description

[Detailed Description of the Invention] (Industrial Application Field) The requirements for grease used in the lubricating parts of various mechanical elements have become even stricter due to the spread of maintenance-free technology, and greases with better heat resistance and mechanical stability have become more demanding. Grease with a high temperature is desired.

Greases with excellent heat resistance and mechanical stability are required in various lubrication equipment, and the performance requirements for greases used in steelmaking equipment, automobile parts, etc., under high-temperature conditions or under conditions subject to strong shearing. are demanding and need a grease that can withstand those conditions.

The present invention relates to a lubricant composition used under such severe conditions.

(Prior art) Semi-solid lubricants such as grease have various advantages such as being difficult to scatter or leak, have a simple sealing mechanism, and can be used in a wide range of temperatures. It is widely used in various electrical products, automobile parts, etc.

Conventionally, metal soap grease (for example, lithium soap grease) has been used in various lubricated parts. However, metal soap grease lacks heat resistance at high temperatures exceeding 150°C, so there is a possibility of it scattering or leaking.Recently, urea grease, which has better heat resistance, is being used. became.

Metal soap grease such as lithium grease, which has excellent versatility, is used for centrally-greased bearings in steel manufacturing equipment, etc., but urea grease is preferably used for bearings that are exposed to high temperature conditions. .

Furthermore, conventional urea greases include diurea, triurea,
There are many types such as tetraurea, polyurea, polyurethane urea, etc., but diurea grease, which has two urea groups in the thickener molecule, is the mainstream because it has excellent thermal stability, mechanical stability, and thermosetting properties. there were.

(Problems to be Solved by the Invention) Various urea greases, including diurea grease using a diurea compound as a thickener, have a structure with a urea group in the molecule. Furthermore, as shown in the structural formula below,
The shape of the micelles formed as an aggregate of each urea molecule, that is, the thickener micelles, is formed by hydrogen bonds with hydrogen atoms and oxygen atoms within the urea group, as shown in formula (2). It is said that

The deterioration of urea grease is thought to occur when the thickener contained in the grease is subjected to heat or mechanical shearing, resulting in changes in the hydrogen bonds forming the micelle shape. In the case of diurea grease, by measuring the thermogravimetric change of the diurea compound, which is a thickener, it was found that decomposition occurs at 220 to 225°C. Use under temperature conditions is basically unfavorable.

(Means for Solving the Problems) The present invention was achieved as a result of intensive studies to further strengthen the degree of hydrogen bonding between urea compound molecules among diurea greases.

That is, the present invention is based on the following general formula % (1) (wherein and R5 are aliphatic, cyclocyclic, or aromatic hydrocarbon groups having 1 to 22 carbon atoms, and are the same as each other) However, R2 and R4 are aliphatic, cyclocyclic, or aromatic hydrocarbon groups having 1 to 8 carbon atoms, and may be the same or different from each other, R3
The present invention relates to a lubricant composition characterized in that it contains 5 to 50% by weight of a compound represented by (representing an aliphatic, cyclocyclic, or aromatic hydrocarbon group having 6 to 14 carbon atoms). The compound shown in formula (1) is a diurea compound having two urea groups at the center of the molecular chain, but there are two urea groups at both ends.
It is characterized by having amide groups. The micelle structure of urea grease formed by a compound with such a structure and base oil makes it possible to form four hydrogen bonds between molecules as shown in formula (3). It has superior heat resistance and mechanical stability compared to diurea grease with the structure shown. In the conventional technology, in the case of diurea grease, the thickener decomposes under conditions of 220 to 225°C or higher. This is due to the breaking of intramolecular bonds,
Therefore, by strengthening the bonds between molecules, thermal stability,
A thickener with good shear stability is formed.

-i Urea Grease thickeners usually contain two or more polar groups, that is, urea groups, and have a large molecular weight. Molecules with many polar groups also have strong intermolecular bonds.

On the other hand, the larger the molecule, the poorer its ability to retain oil as a thickener.

From the above, it has many polar groups as a thickener,
We selected one with a small molecule and conducted extensive research.

Representative examples of raw materials for the compound shown in formula (1) are as follows: two molecules of N-(4-aminophenyl)acetamide (monoamine), which is an intermediate for synthetic dyes, and one molecule of diphenylmethane-4, Obtained by polyaddition reaction of 4'-diisocyanate (diisocyanate). Furthermore, N-(
4-Aminophenyl)acetamide can be obtained by easily reducing N-(4-nitrophenyl)acetamide with a nickel or platinum catalyst in an alcohol solution under a hydrogen stream.
(4-aminophenyl)acetamide.

Such aromatic amines are easily converted into diazonium salts and coupled with aromatic phenols and aromatic amines to produce azo compounds, making them extremely important compounds in the dye industry, and their availability is comparatively low. It is easy to understand.

In order to strengthen the intermolecular bonding force of the diurea compound obtained by the polyaddition reaction between diisocyanate and monoamine, the present inventors have conducted intensive studies and found that diisocyanate and N-(4-aminophenyl)acetamide, etc. We have discovered that a diurea compound having two amide groups, that is, diamide diurea (hereinafter abbreviated as DADU), obtained by combining an aromatic monoamine with an amide group, has significantly superior physical properties compared to conventional diurea compounds. It is. In addition, the manufacturing method of DADU and DADU
The method for producing grease using DU as a thickener is as follows.

1) When reacting in a base oil, add the diisocyanate to the base oil and keep it at a temperature of 40 to 120 ° C. If the diisocyanate is solid, confirm complete dissolution, add the monoamine, and further raise the temperature to 160 ° C. The mixture is brought to a temperature of ~200°C, maintained within the temperature range for 0 to 120 minutes, cooled, and kneaded in a three-roll mill to form a grease. In this case, the lubricant composition of the present invention needs to contain 5 to 30% by weight of the compound of formula (1) in the base oil as a grease thickener. If it is less than 5% by weight, which is outside the range stipulated in the present invention, it will be too soft and almost liquid and will not have the characteristics of a grease, and if it exceeds 30ffl-1%, it will be too hard (too hard,
This causes problems such as poor lubrication in the lubrication of bearings, etc.

2) When reacting in a solvent, add the diisocyanate to the high boiling point solvent and completely dissolve it. In addition, if it is difficult to dissolve, heat as necessary.

Furthermore, after complete dissolution, the monoamine is added and reacted, and the solvent is removed. Next, this DADU is mixed into the base oil and 3
Knead with this roll mill to form a semi-solid viscous consistency.

However, in this case, a large amount of thickener is required, and the base oil needs to contain 25 to 50% by weight of the thickener. As in the case of reacting in base oil, if it is less than 25% by weight, it will be too soft and almost liquid and will not have the characteristics of a grease, and if it exceeds 50% by weight, it will become too hard. , causing problems such as poor lubrication in the lubrication of bearings, etc.

There are no restrictions on the base oil, and at least one of ester oil, ether oil, polyα-olefin oil, and mineral oil shall be used, and antioxidants, rust preventives, oiliness agents, extreme pressure agents, etc. may be added. It may also contain an agent.

The DADU according to the present invention is preferably an ester oil base oil or one in which one-third or more of the base oil is an ester oil from the viewpoint of affinity and compatibility with the base oil.

(Function) The present invention relates to a diurea grease that allows four hydrogen bonds to be formed between molecules, like DADU. Although the effect of the lubricant composition of the present invention is not clear, it is thought to be as follows.

The micellar structure of conventional urea greases using urea compounds as thickeners is said to be formed by two strong hydrogen bonds between hydrogen and oxygen atoms within the urea group. Further, since such hydrogen bonds are relatively hydrophobic, they are resistant to shearing in the presence of water, which is one of the environments in which urea grease is used.

When urea grease undergoes a change in properties, it is often due to a change in the thickener that thickens the base oil, that is, a change in the molecules of the urea compound. The changes are often due to changes in the hydrogen bonds that hold the molecules together due to heat, water, and mechanical shear forces. The phenomenon and degree of change also vary depending on the type of amine compound that combines with the diisocyanate to form the urea compound, such as aliphatic amines, cyclocyclic amines, and aromatic amines. However, diisocyanates and diurea compounds formed from these monoamine compounds,
The number of urea groups in the molecule is limited to two. Therefore, the number of hydrogen bonds between molecules that can form thickener micelles is limited to two, and it cannot be said that they necessarily have strong bonds.

Phenomena such as grease softening due to mechanical shearing are observed. Furthermore, in manufacturing, it is extremely difficult to make a pure compound, so it cannot necessarily be said to be a good grease.

However, it is believed that the DADU according to the present invention allows not only hydrogen bonding due to two urea groups but also hydrogen bonding due to two amide groups. Therefore, D.A.D.
Diurea grease using U as a thickener is considered to be extremely stable against heat, water, and mechanical shearing forces compared to other diurea greases.

Furthermore, there are greases that use urea compounds such as triurea, which has three urea groups, and tetraurea, which has four urea groups, as thickeners, but these greases harden after being repeatedly heated and cooled (example). and Comparative Examples) Hereinafter, the present invention will be explained in more detail with reference to Examples and Comparative Examples.

81.8 g of diphenylmethane 4,4' diisocyanate was added to 820 g of pentaerythritol tetraester oil and heated to 70''C while stirring.

This is followed by N~(4-aminophenyl)acetamide 98.
Add 2g and raise the temperature to 190″C while stirring.
After that, it was left to cool to room temperature and kneaded using a three-roll mill.
The desired composition was obtained.

1. 71.8 g of hexamethylene diisocyanate was added to 800 g of flamed pentaerythritol tetraester oil and heated to 70°C while stirring. 128.2 g of N-(4-aminophenyl)acetamide was added to this, and the temperature was raised to 190°C while stirring, then allowed to cool to room temperature, and kneaded in a three-roll mill to obtain the desired composition. Ta.

73.4 g of tolylene diisocyanate was added to 800 g of pentaerythritol tetraester oil and heated to 70"C while stirring. To this was added 126.6 g of N-(4-aminophenyl)acetamide and stirred. The mixture was heated to 190'C while performing the above steps, and then allowed to cool to room temperature, and kneaded using a three-roll mill to obtain the desired composition.

73.6 g of diphenylmethane 4.4' diisocyanate was added to 850 g of pentaerythritol tetraester oil and heated to 70° C. while stirring.

76.4 g of n-octylamine was added thereto, and the mixture was heated to 205°C while stirring, then cooled to room temperature, and kneaded using a three-roll mill to obtain the desired composition.

Static transparency Mainly 770 g of pentaerythritol tetraester oil and 131.9 g of diphenylmethane 4,4'-diisocyanate.
was added and heated to 70''C while stirring.

Add 98.1 g of aniline to this, and add 1 g of aniline while stirring.
The temperature was raised to 90°C, then cooled to room temperature, and kneaded using a three-roll mill to obtain the desired composition.

Next, the lubricant compositions of the above Examples and Comparative Examples were subjected to a thermal stability test according to the test method shown below, and the obtained results are shown in Tables 1 and 2, respectively.

Testing friend [Test 1] Extract the oil from the sample grease with n-hexane, use the residue and the sample grease as the test sample, and measure the weight of the test sample against the heat when it melts in an N2 gas atmosphere using a differential differential thermal balance. The change was determined, and the superiority or inferiority of thermal stability was determined based on the difference in weight loss initiation temperature.

[Test 2] Sample grease was applied to a thickness of 1.0M on a 5pcc steel plate that had been cleaned with petroleum benzene and acetone, and was left at 180°C and 200°C for 24 to 200 hours.
After that, it is left to cool to room temperature, and the worked penetration is measured using a 1/4 scale consistency in accordance with JIS K 22205.3. was determined.

The judgment criteria are as follows.

Work penetration difference O~10 ◎ 11-30 0 31~50 Δ 50× In addition, hardening was evaluated as -, and softening was evaluated as 10.

Further, Examples and Comparative Examples for selecting the content and base oil of the lubricant composition of the present invention are shown below.

1 trip ±↓ 22.7 g of diphenylmethane (4.4' diisocyanate) was added to 950 g of pentaerythritol tetraester oil and heated to 70''C while stirring.

To this, N-(4-aminophenyl)acetamide 27,
Add 3g and raise the temperature to 190°C while stirring.
After that, it was left to cool to room temperature and kneaded using a three-roll mill.
The composition of Example 4 was obtained.

136.3 g of diphenylmethane 4,4' diisocyanate was added to 700 g of back-opened epentaerythritol tetraester oil and heated to 70°C while stirring.

To this, N-(4-aminophenyl)acetamide 163
．． 7 g was added, and the temperature was raised to 190° C. while stirring, then allowed to cool to room temperature, and kneaded using a three-roll mill to obtain the composition of Example 5.

Length targeted tantan diphenylmethane 4.4' diisocyanate 113゜6
g was added to DMF10f and heated to 80°C to completely dissolve. To this, 1364 g of N-(4-aminophenyl)acetamide was added, and the temperature was maintained at 80''C for 30 minutes while stirring.Then, the entire reaction solution was poured into a water bath at 302 to precipitate the reactant. The reaction material was obtained by further filtration.

This reactant was ground in an agate mortar to a particle size of 100 μm or less, 250 g was dispersed in 750 g of pentaerythritol tetraester oil, and kneaded in a three-roll mill to obtain the composition of Example 6.

7. 15 6 Example 7. Compositions of Comparative Examples 5 and 6 were obtained.

Compositions of Examples 8 to 11 were obtained in the same manner as in Example 1, except that the ingredients shown in Table 3 were used.

Example 1 above. The consistency and perfect score of the compositions of Examples 4 to 11 and Comparative Examples 3 to 6 are also listed in Tables 3 and 4.

(Effects of the Invention) By using the compound of formula (1) as a thickener, the lubricant composition of the present invention has excellent thermal stability and mechanical stability, as is clear from Examples and Comparative Examples. The effect was that the results were also improved.

Claims (1)

[Claims] 1. The following general formula R_1CONHR_2NHCONHR_3NHCONH is added to the base oil.
R_4NHCOR_5---(1) (R_1 and R_5 in the formula are aliphatic, cyclocyclic, or aromatic hydrocarbon groups having 1 to 22 carbon atoms and may be the same or different from each other, R_2 and R_4 has 1 to 1 carbon atoms
8 aliphatic, cyclocyclic, or aromatic hydrocarbon groups, which may be the same or different from each other, and R_3 is an aliphatic, cyclocyclic, or aromatic hydrocarbon group having 6 to 14 carbon atoms. A lubricant composition characterized by containing 5 to 50% by weight of a compound represented by the following formula.