JPH0692592B2 - Urea grease composition - Google Patents

Description

TECHNICAL FIELD OF THE INVENTION The present invention relates to a diurea grease composition.

In particular, the present invention relates to a high-quality diurea grease composition having a high dropping point, excellent mechanical stability at high temperatures, very little thermosetting property, and extremely good acoustic characteristics.

Prior art Conventional literature relating to diurea grease includes, for example, that described in Japanese Examined Patent Publication No. 46-4489.
ONHR ¹ NHCONHR (wherein R ¹ represents a divalent aromatic hydrocarbon group and R represents a cycloalkyl group). Japanese Patent Publication 55-
No. 11156 has the general formula R ₂ NHCONHR ₁ NHCONHR ₃ 2 for R ₁
Valent aromatic hydrocarbon group, R ₂ and R ₃ are cyclohexyl group or C _{7 to} C ₁₂ cyclohexyl derivative group, or diurea type grease having C _{8 to} C ₁₂ alkyl group and cyclohexyl group or its derivative and alkyl group. Is also disclosed at any of the ends of diurea. Further, U.S. Pat. A diurea compound containing parachloroaniline as a component is disclosed. Regarding low noise urea grease, see JP-A-58-1856
No. 93 is a diurea grease which contains one or more kinds of alkenyl succinimide, alkylbenzene sulfonic acid metal salt and petroleum sulfonic acid metal salt and has improved noise.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention Lubricating greases enriched with urea compounds are characterized by heat resistance and oxidation stability, and are expected to be greases for high temperature and long life. However, commercially available urea grease has problems in curing phenomena and mechanical stability at high temperatures, and it has been recognized that it should be improved. Urea grease can be used at high temperature for a long time as compared with lithium grease, but it has poor acoustic characteristics and cannot be used in places where low noise is required.

On the other hand, the environment in which grease is used becomes extremely severe with the downsizing and speeding up of mechanical devices, and there is a demand for a grease that can be used at high temperature for a long time and has excellent low noise characteristics.

The present invention is a urea grease having extremely good various properties as a result of conducting an improvement study on thermosetting property and mechanical stability at high temperature, which has been conventionally regarded as a defect, and further acoustic properties of the urea grease. I was able to develop.

MEANS FOR SOLVING THE PROBLEMS The present invention includes a compound represented by the general formula (a) R ₁ NHCONHR ₂ NHCONHR ₃ (b) R ₄ NHCONHR ₅ NHCONHR ₆ (wherein R ₂ is a diphenylmethane group, and R ₁ and R ₃ are each a carbon number). 8 is a linear or branched saturated alkyl group, R ₅ is a tolylene group or a vitrylene group, and R ₄ and R ₆ are each an alkyl-substituted aromatic group or a halogen-substituted aromatic group) 2 to 30% by weight of a thickening agent with respect to a mineral oil or a synthetic oil, which is a mixture having a component (b) content of 5 to 90 mol% and a component (a) content of 95 to 10 mol%. The present invention relates to a urea grease composition characterized by containing.

Many diurea greases are usually compounds that consist of the reaction of diisocyanates with primary amines in lubricating oils,
A large number of greases can be made by selecting the types of isocyanate and amine, and various characteristics are also greatly different.

For example, if 2 mol of alkylmonoamine is used for 1 mol of diisocyanate, both end groups become alkyl groups, and if 2 mol of allylmonoamine is used for 1 mol of diisocyanate, both end groups become allyl groups. Diisocyanate 1m
1 mol of alkyl monoamine and allyl monoamine to ol
If 1 mol is used, a grease having an alkyl group and an allyl group introduced at both ends can be prepared. Thus, diurea grease can be roughly classified into three types of structures. Generally, a diurea grease having an alkyl group as an end group is inferior in oxidation resistance and heat resistance to a diurea grease having an allyl group as an end group, but tends to have excellent consistency yield and mechanical stability.

However, this is only a general tendency, and not all diurea greases having an alkyl group as an end group are excellent in yield and mechanical stability. Not all have excellent heat resistance. Many of them show a fluidized state and a remarkable thermosetting phenomenon. Even when the number of diisocyanates is limited to one as described above, the performance of the grease greatly changes depending on the type of amine, and the various performances can naturally change by changing the type of isocyanate.

The present inventors prototyped a large number of diurea greases and conducted a test study.As a result, they have a high dropping point, little heat curing at high temperature, excellent heat resistance and mechanical stability, and excellent acoustic characteristics. I found grease.

That is, in the diurea compound represented by the formula (a) R ₁ NHCONHR ₂ NHCONHR ₃ (b) R ₄ NHCONHR ₅ NHCONHR ₆ , R ₁ and R ₃ of the component (a) are linear or branched saturated alkyl groups, R ₂ is a diphenylmethane group, and R ₄ and R ₆ of the component (b) are alkyl-substituted aromatic groups or halogen-substituted aromatic groups and R ₅
Is a tolylene group or a vitrylene group.

The urea grease composition of the present invention is a mixture of the component (a) and the component (b), wherein the diurea compound contains the component (b) in an amount of 5 to 90 mol% and the component (a) in an amount of 95 to 10 mol%. A thickener containing 2 to 30% by weight, preferably 5 to 20% by weight, of a base oil which is a mineral oil or a synthetic oil, is a grease having extremely excellent performance.

When the ratio of the component (b) is less than 5 mol%, the effect of mixing and using the component (a) and the component (b) is small, while when the ratio of the component (b) exceeds 90 mol%. It is not preferable in terms of consistency yield.

In the grease of the present invention, R ₂ is a diphenylmethane group and R ₁ and
An identical addition of a diurea compound in which R ₃ is an octyl group as an end group and a diurea compound in which R ₅ is a tolylene group or a vitrylene group and R ₄ and R ₆ are an alkyl-substituted aromatic group or a halogen-substituted aromatic group as an end group It is a diurea grease limited to coexist in a thickener, but even if diurea grease is made by converting R ₁ and R ₃ or R ₂ and R ₄ and R ₆ or R ₅ to compounds other than the above, performance is also improved. No effect at all.

For example, a diurea grease in which R ₁ and R ₃ are octyl groups and R ₂ is a tolylene group or a vitrylene group is just inferior in yield and has poor mechanical stability.

Most of the diurea greases in which R ₁ and R ₃ are alkyl groups having 10 to 18 carbon atoms and R ₂ is a tolylene group, a vitylene group or a diphenylmethane group have poor mechanical stability at high temperatures. Furthermore, the diurea grease in which R ₄ and R ₆ are alkyl-substituted aromatic groups or halogen-substituted aromatic groups and R ₅ is a diphenylmethane group has very poor acoustic properties.

In the grease of the present invention, by combining the components (a) and (b), the defects of the component (a) alone and the defects of the component (b) alone are completely eliminated.

For example, a diurea grease containing a component (a) represented by the octyl group of R ₁ and R ₃ and the diphenylmethane group of R ₂ is excellent in thickening effect, mechanical stability and acoustic characteristics by itself. A drop in drip point is observed as the volume is reduced. On the other hand, a diurea grease containing a component (b) in which R ₄ and R ₆ are alkyl-substituted aromatic groups or halogen-substituted aromatic groups and R ₅ is a tolylene group or a vitrylene group has a high dropping point by itself, On the other hand, it is very stable and has relatively good acoustic characteristics. However, it has the disadvantage of poor consistency yield and mechanical stability. By combining the components (a) and (b), which are the components of the thickeners of both these greases, and making them coexist in the same thickener, a diurea grease of extremely excellent performance that maximizes the excellent performance of both is obtained. can get. Further, in order to further improve the performance of this lubricating grease, various additives such as an antioxidant, a rust preventive, an extreme pressure agent and an antiwear agent may be added.

The diurea grease of the present invention has a high dropping point, has less tendency to cure at high temperatures as compared with currently marketed urea grease, and is excellent in mechanical stability and acoustic characteristics.

Hereinafter, the present invention will be described with reference to examples. In addition, the characteristics of the urea grease of the present invention were clarified by also describing comparative examples.

Example The diisocyanate of component (b) and 60 parts by weight of base oil in the compounding ratios shown in Table 1 were placed in a grease kettle and heated to about 80 ° C. to dissolve the diisocyanate, and then 20 parts by weight of this was added. The aromatic amine of component (b) dissolved in the base oil is gradually added and vigorously stirred. After about 10 minutes, the component (a), diphenylmethane 4,4'-diisocyanate, was added and then 20
Octylamine dissolved in 1 part by weight of base oil is added and stirring is continued.

Although the temperature rises due to the reaction between the diisocyanate and the amine, the mixture is stirred for about 30 minutes in this state and then heated to 170 ° C. to complete the reaction. Then, it was left to cool to room temperature and kneaded to prepare grease. The viscosity of the mineral oil shown in the examples is 11 cst (100
C)) and the poly alpha olefin oil is 12 cst (100C). Table 1 shows the consistency, dropping point, shell roll (150 ° C., 24 h), and consistency after heating at 180 ° C. (25 ° C., immiscible) of the grease of each example, and the result of the acoustic test.

Further, the grease of Example 1 was prepared by adding additives such as an antioxidant and a rust preventive (Example 10), and the results of tests conducted in comparison with a commercially available urea grease are shown in Table 2. It was In Table 2, the commercial product A is tetraurea grease (AMOCO product name: RICON1364), the commercial product B is alicyclic diurea grease (Nippon Petroleum product name: Pyronoc Universal No. 2), and the commercial product C is Aromatic Diurea Grease (NOK Cluber Product Name: NOK Cluber BT28
It was 0).

Comparative Example Diisocyanate and 80 parts by weight of mineral oil in the mixing ratios shown in Tables 3 and 4 were placed in a grease kettle and heated to about 80 ° C. to dissolve the diisocyanate, and then dissolved in 20 parts by weight of mineral oil. The amine was added and stirred. Continue stirring in this state for about 30 minutes, then heat to about 170 ℃ to complete the reaction,
After allowing to cool to room temperature, the mixture was kneaded to prepare grease. The properties of each comparative example are shown in Tables 3 and 4.

The test items were measured according to the following methods.

Consistency: JIS K-2220 Drop point: JIS K-2220 Shell roll: ASTM D 1831 After heating at 150 ℃ Consistency: According to JIS K-2220, 1/4 consistency meter is filled with grease and heated at 150 ℃ for 72 hours. After cooling, the immiscible consistency at 25 ° C was measured.

Acoustic test: Acoustic tester NSK GREASE NOISE TESTER (Nippon Seiko Co., Ltd.) based on Japanese Examined Patent Publication No. 53-2357 (Invention title "Measurement of solid foreign substances mixed in grease, applicant" Nippon Seiko Co., Ltd. ") Bearing) was measured for each grease.

Effects of the Invention The effects of the present invention are as follows.

(1) The urea grease of the present invention has a high dropping point and is remarkably excellent in mechanical stability at high temperatures.

(2) The urea grease of the present invention has a very stable grease structure even when it is exposed to a high temperature for a long time, and the curing phenomenon due to heat is small.

(3) The urea grease of the present invention has excellent acoustic characteristics that conventional urea grease does not have.

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Claims (1)

[Claims] 1. A compound represented by the general formula (a) R ₁ NHCONHR ₂ NHCONHR ₃ (b) R ₄ NHCONHR ₅ NHCONHR ₆ (wherein R ₂ is a diphenylmethane group, and R ₁ and R ₃ are each a straight chain having 8 carbon atoms or Branched saturated alkyl group, R ₅
Represents a tolylene group or a vitrylene group, and R ₄ and R ₆ represent an alkyl-substituted aromatic group or a halogen-substituted aromatic group, respectively. ) A mixture of diurea compounds represented by the formula (5), wherein the proportion of component (b) is 5 to 90 mol% and the proportion of component (a) is 95 to 10 mol% in mineral oil or synthetic oil. The urea grease composition is characterized by containing 2 to 30% by weight.