JPS6411680B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to high temperature resistant lithium grease. Particularly, the present invention has a continuous operating temperature of 150°C to 200°C.
The present invention relates to a high temperature resistant lithium grease suitable for use in. Currently, lithium grease has a share of more than 50% in the market, and due to its excellent performance, its share is likely to increase in the future. However, the operating conditions for grease have become harsher due to the operation of machines and equipment at high temperatures, high speeds, and high loads, and in order to save labor and resources, equipment has become smaller, lighter, and lubricated. As the time has been extended, there are many applications where regular lithium grease is no longer sufficient to meet the high-temperature resistance and lubrication life required of grease, and a high-temperature-resistant grease that can withstand even higher temperatures and has a longer lubrication life is desired. There is. The temperature limit for continuous use of normal lithium grease is 120°C to 130°C, and at temperatures above 150°C, lubrication failure occurs in a short period of time due to causes such as oxidation and softening.
Grease lubrication parts in current automobiles, electric motors, steel machinery and other industrial machinery and equipment are
There are many cases where the temperature exceeds °C, and excellent high-temperature greases have emerged. For example, in cars equipped with disc brakes, wheel bearing grease is at risk of being exposed to temperatures of 150°C to 200°C due to the frictional heat generated by braking, and with normal lithium grease, it softens and flows, causing it to leak from the inside of the hub. It has the disadvantage that it has a strong possibility of leakage or rapid deterioration due to oxidation, resulting in poor lubrication. In order to improve these drawbacks, the present inventors have endeavored to develop a heat-resistant lithium grease that takes advantage of the excellent performance of lithium grease and has a high dropping point, and have arrived at the present invention.
The grease of the present invention exhibits excellent performance not only in high-temperature properties but also in all other respects such as lubricity, water resistance, and mechanical stability, and has an extremely long bearing life. The present invention consists of a lubricating oil as a main component, and a thickening agent for the lubricating oil. Lithium salts are used, and (c) a dispersant selected from alkaline earth metal phosphonates, alkaline earth metal salicylates and polyalkenyl succinimides is used as a propagation aid, and these are required in the lubricating oil. This relates to a high-temperature resistant lithium grease that is dispersed in an amount that provides a high degree of hardness. The fatty acid component (a) of the grease of the present invention includes higher hydroxy fatty acids having 16 to 20 carbon atoms, preferably higher hydroxy fatty acids having 18 carbon atoms. For example, an industrial castor oil hydrogenated fatty acid containing _C18 hydroxystearic acid as a main component is used, and in particular when castor oil hydrogenated fatty acid is used, a grease with the best properties can be obtained. Furthermore, when producing the lithium salt of phosphoric acid or phosphorous acid, which is component (b) of the grease of the present invention, it is also possible to directly neutralize the phosphoric acid or phosphorous acid with lithium hydroxide or lithium oxide. Yes, but
When considering dispersion in lubricating oil, it is better to use it as an ester. Examples of phosphate esters include trimethyl phosphate, triethyl phosphate, triisopropyl phosphate, tributyl phosphate, trilauryl phosphate, tristearyl phosphate, triphenyl phosphate, tricresyl phosphate,
Tri-2-ethylhexyl phosphate, tridecyl phosphate, trinonylphenyl phosphate, diphenyl monodecyl phosphate, trithiotrilauryl phosphate, tri-2-chloroethyl phosphate, or acidic esters thereof are suitable. Also, the same esters as above are suitable for phosphorous acid. When an ester is used, trilithium phosphate or trilithium phosphite or an acid salt thereof and an alkyl alcohol or allyl alcohol are produced by reaction with lithium hydroxide or lithium oxide.
If alcohol remains in the grease, the stability of the product will be slightly inferior, so better results will be obtained if it is removed by evaporation. Therefore, the phosphoric acid ester or the phosphorous acid ester is preferably an ester of a lower alcohol. Thickening aids used in the greases of the present invention include metal salt dispersants such as alkaline earth metal phosphonates, alkaline earth metal salicylates, and ashless dispersants of polyalkenylsuccinimides. The grease of the present invention contains 2 to 30% by weight, preferably 5 to 20% by weight of thickener, based on the total weight of the grease. In the above-mentioned thickening agent, the molar ratio of lithium soap (component (a)) to lithium salt of phosphoric acid or phosphorous acid (component (b)) is 1:0.1 to 1:2. The above thickening aids are based on the total weight of the grease.
Use 0.5-10wt%, preferably 1.0-5.0wt%. Next, the present invention will be described with reference to Examples, but the present invention is not limited thereto. Example 1-4 Component (a) higher hydroxy fatty acid, lithium hydroxide in the amount shown in Table 1, an appropriate amount of water, and about 1/2 of the blended mineral oil in the mixing ratio of the raw materials shown in Table 1. After making lithium soap by adding the amount of
Grease was made by heating and kneading at 200℃. When incorporating component (b), the amount of component (b) shown in Table 1 is mixed with component (a). The above-mentioned thickening aid is mixed in the amount shown in Table 1 with the remaining amount of mineral oil. The lubricating oil used in the examples has a viscosity of 14cSt (100℃),
It is a mineral oil with a viscosity index of 98. For comparison, greases having the compositions shown in Table 1 were prepared (Comparative Examples 1 and 2) and their performance was tested. Greases were also prepared using Ca sulfonate as a dispersant (Reference Examples 1-3) and higher fatty acids instead of higher hydroxy fatty acids (Reference Example 4), and tested in the same manner.

[Table] * Antioxidant, oiliness improver, rust preventive agent The toughness and dropping point of the grease in each example are
As shown in the table.

[Table] Table 3 shows the results of comparing the properties of the grease of the present invention (Example 4) with commercially available high-temperature greases and general-purpose lithium greases. Table 3 shows that the grease of the present invention exhibits excellent properties at high temperatures (150°C to 200°C).

[Table] It was also found that the greases of the present invention of Examples 1 to 3 also exhibited excellent properties at high temperatures comparable to those of Example 4 (150°C to 200°C).

Claims (1)

[Claims] 1 The main component is lubricating oil, and as a thickening agent (a) lithium soap made from higher hydroxyl fatty acids having 16 to 20 carbon atoms and (b) lithium salt made from phosphoric acid ester or phosphite ester. (c) A dispersant selected from alkaline earth metal phosphonates, alkaline earth metal salicylates, and polyalkenyl succinimides as a growth aid.