JPS6326798B2 - - Google Patents

Description

[Detailed description of the invention]

B. Purpose of the invention Industrial application field In the current grease market, lithium grease is 50%
% and is widely used as a general-purpose grease, but it is a grease that has a long life under high temperatures for the purpose of harsher operating conditions, extending the life of equipment, extending the greasing interval, and reducing the amount of grease used. has become desirable. Although urea grease is gradually being used in a wider range of applications due to its excellent high temperature resistance, it often has drawbacks such as hardening at high temperatures and poor mechanical stability. Prior Art Conventionally, as a literature related to urea grease, for example, Japanese Patent Publication No. 51-965 describes a urea grease containing a diurea thickener containing one or two aromatic nuclei and having an aliphatic group at the terminal group. Grease is listed. Japanese Patent Publication No. 55-11156 contains one aromatic nucleus, cyclohexyl at the end, C ₇ ~
Urea greases are described that include diurea thickeners having _C12 cyclohexyl derived groups or _C8 to _C20 alkyl groups. Japanese Patent Publication No. 58-11920 describes aliphatic hydrocarbons, alicyclic hydrocarbons, and aromatic hydrocarbons that have two urea groups in one molecule and whose terminal groups are the base oil components of lubricating grease. A high-temperature, long-life urea-based grease composition is described which is comprised of hydrocarbons and whose groups are in the same proportion as the base oil. Also, U.S. Patent No.
Publication No. 4065395 contains a methyl-substituted aromatic group,
Diurea greases are described that include diurea thickeners having methyl-substituted or chloro-substituted aromatic groups at the end groups. Problems to be Solved by the Invention The present invention relates to a urea grease that improves the properties that have hitherto been considered to be disadvantageous and has extremely good performance that can be used in a wide range of applications. For example, in steel equipment, especially continuous casting equipment, grease is supplied to bearings by automatic lubrication, and lubrication must be performed at high temperatures and in the presence of water. Grease with good properties such as corrosion resistance and rust prevention properties is required. The urea grease of the present invention is
It has excellent performance in all of these areas, and has been proven to have extremely good performance in actual equipment use, extending the life of the equipment,
This invention relates to a grease that can reduce repair costs and lubricant costs. B. Means and action for solving the structural problems of the invention Urea grease is usually produced by the reaction of isocyanate and primary amine in lubricating oil.
By selecting the type of isocyanate and amine, greases with various properties can be made. The performance of these urea greases varies depending on the type of isocyanate and amine selected and the reaction method, but greases that use diurea compounds as a thickening agent are often used because of their good performance and ease of production. Various types of grease are produced. The above diurea compounds are often produced by the reaction of diisocyanates with primary monoamines, or by the reaction of primary monoamines with diisocyanates or
It is produced by the reaction of grade diamine and monoisocyanate, but its performance is greatly affected by the type of end group. Diurea grease whose terminal group is an alkyl group is often inferior to diurea grease whose terminal group is an aromatic group in terms of heat resistance, oxidation resistance, water resistance, etc. As a result of various studies, the present inventors found that
We have discovered that even if the terminal group is an alkyl group, it is possible to create a diurea grease with extremely good properties by selecting the number of carbon atoms and molecular structure of the alkyl group. For example, when diurea grease is made by reacting a diisocyanate with a primary monoamine, if an alkyl monoamine is used, the terminal group becomes an alkyl group. It has the advantage of being easy to handle. As the alkyl monoamine, a linear alkylamine or a branched alkylamine having 3 to 20 carbon atoms can be used. Especially carbon number 8 to 18
fatty acid amines, e.g. caprylyl (octyl)
Amine, caprylic (decyl) amine, lauryl (dodecyl) amine, myristyl (tetradecyl)
Preferred are amine, palmityl (hexadecyl) amine, stearyl (octadecyl) amine, oleyl (octadecenyl) amine, and the like. On the other hand, the diisocyanates include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, a mixture of 2,4 and 2,6-tolylene diisocyanate, diphenylmethane-4,
4'-diisocyanate, 3,3'-vitrylene-
Aromatic diisocyanates such as 4,4' disocyanate can be used. As a result of research using the above-mentioned raw materials, the present invention uses aliphatic amines having 8 and 12 carbon atoms, and the proportion of alkyl groups having 12 carbon atoms contained in the terminal alkyl groups (R ₁ , R ₂ ). However, it has been discovered that a diurea grease with extremely excellent performance can be produced when the amount is 5 to 90 mol%. In other words, the grease of the present invention has unparalleled shear stability from low to high temperatures and in the presence of water, and has extremely good lubricity and pumpability. . Of course, it also has extremely good heat resistance, with a dropping point of over 260℃,
Hardening phenomenon when heated to high temperatures is small, and oil separation at high temperatures is also low. The content of the present invention will be specifically shown in Examples, but there is a lack of heat resistance, poor thermosetting properties, and poor shear stability at high temperatures and in the presence of water, which are usually observed in diurea greases whose terminal groups are alkyl groups. These shortcomings have been completely removed. For example, a diurea compound terminated with an alkyl group such as an octadecyl group (C ₁₈ ) alone makes a reasonably good grease, but the increasing effect is too good, so the amount of the increasing agent (diurea compound) must be reduced. Otherwise, it will be impossible to make soft grease, resulting in poor heat resistance, high oil separation at high temperatures, poor shear stability in the presence of water, and high thermosetting properties. have. On the other hand, a diurea compound having a caprylyl group (C ₈ ) as a terminal group produces a good grease when used alone, but it lacks shear stability at high temperatures and when mixed with water. Furthermore, diurea compounds having a lauryl group (C ₁₂ ) as a terminal group have poor growth effect and cannot be said to have good shear stability. However, when using a mixture of octyl and dodecyl groups, heat resistance,
It produces a grease that is excellent in all performances, including shear stability from low to high temperatures, shear stability in the presence of water, pumpability, thermosetting properties, and lubricity. That is, the formula R ₁ NHCONHR ₂ NHCONHR ₁ R ₁ NHCONHR ₂ NHCONHR ₃ R ₃ NHCONHR ₂ NHCONHR ₃ (In the formula, R ₂ is an aromatic group having 6 to 15 carbon atoms, R ₁ is an octyl group, and R ₃ is a dodecyl group. , R ₁ and R ₃
When a mixture of diurea compounds (the proportion of dodecyl groups in the base oil is 5 to 90 mol %) is contained as an increasing agent in an amount of 2 to 35% by weight based on the base oil, which is mineral oil or synthetic oil, it is extremely effective. Diurea grease with good performance can be made. If the content of the alkyl group having 12 carbon atoms is less than 5 mol %, the effect of mixed use will be small, while if it exceeds 90 mol %, it is unfavorable from the viewpoint of hardness yield. The grease of the present invention has the advantage that the stiffness can be changed by changing the molar ratio of C ₈ /C ₁₂ in the urea compound even if the thickening agent content is the same, making it possible to obtain a grease with good performance. It has the characteristics of being easy to manufacture. Furthermore, it goes without saying that additives such as antioxidants, rust preventives, extreme pressure agents, and antiwear agents can be added to the grease of the present invention to improve the performance of the grease. The present invention will be explained below with reference to Examples. Example Diisocyanate and base oil were added to a grease pot at the mixing ratio of raw materials shown in Table 1, and heated to about 80°C. After dissolving the diisocyanate, various amines in amounts shown in Table 1 were added thereto and stirred. Although the temperature rose due to the reaction between the diisocyanate and the amine, stirring was continued in this state for about 30 minutes, and after the reaction had sufficiently occurred, the mixture was heated to 150°C and kneaded to make a grease. The mineral oil shown in the examples has a viscosity of about 14 cst (100°C), and the diphenyl ether has a viscosity of about 13 cst (100°C). Hardness, dropping point, and oil separation properties in each example (150℃,
24h) are shown in Table 1. It has been found that oil separation properties at high temperatures and shear stability in the presence of water are significantly improved by using a mixture of an alkylamine having 8 carbon atoms and an alkylamine having 12 carbon atoms. As Example 13, a grease was prepared using the same formulation as Example 12, but with the addition of an antioxidant and a rust preventive agent, and the properties were compared with commercially available diurea grease. Table 2 shows the results. It was found that the grease of the present invention has extremely good heat resistance, shear stability at high temperatures, shear stability in the presence of water, heat curing resistance, and pumpability (apparent viscosity).

【table】

[Table] The properties measurement method in Table 1 is as follows. Toughness: JIS K2220 Dropping point: 〃 〃 Oil separation: 〃 〃 Water 10% shell roll: According to ASTM D1831,
Mix 10% water with grease, 80℃
Conduct a 24-hour test and measure the 1/4 mixing degree [JISK2220] at 25°C.

【table】

[Table] Measurement method Chillness: JISK2220 Shell roll: ASTMD1831 Chillness after heating at 180℃: 1/4 according to JISK2220
Fill the temperature measuring device with grease and set it to 180
After heating for 24 hours at °C, cool and measure the degree of immiscibility at 25 °C. Apparent viscosity: JISK2220 C Effects of the invention The effects of the invention are as follows. (1) The urea grease of the present invention has outstanding shear stability, lubricity, pumpability, and heat resistance at high temperatures and in the presence of water. (2) The urea grease of the present invention has a dropping point of 260°C or higher, has short thermosetting properties at high temperatures, and has low oil separation properties at high temperatures. (3) By adding appropriate additives such as antioxidants and rust preventives to the urea grease of the present invention, it was possible to create a grease with extremely excellent performance in all aspects.

Claims (1)

[Claims] 1 Formula R ₁ NHCONHR ₂ NHCONHR ₁ R ₁ NHCONHR ₂ NHCONHR ₃ R ₃ NHCONHR ₂ NHCONHR ₃ (In the formula, R ₂ is an aromatic group having 6 to 15 carbon atoms, R ₁ is an octyl group, and R ₃ is a dodecyl group, R ₁ and R ₃
The ratio of dodecyl groups in the base oil is 5 to 90 mol %) as an increasing agent in a mixture of 2 to 35% by weight of the base oil, which is mineral oil or synthetic oil. A urea grease composition.