JPH0326717B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a grease composition, and more particularly to a grease composition that exhibits good water resistance even at high temperatures. In general, when it comes to lubrication of machinery, there is a risk that moisture may get mixed into the grease and cause it to soften or leak out in bearings of rolling mills in steel mills, ships, automobiles, etc. where water is likely to get mixed in. It was hot. In order to prevent such softening and outflow of grease, attempts have been made to improve the fiber structure of the grease or to add aluminum soap to the grease. However, although these greases exhibit good water resistance at relatively low temperatures around room temperature,
At the high temperatures at which grease is actually used (around 80°C), it has the disadvantage that it becomes liquid due to water contamination. The inventors of the present invention have made intensive studies to eliminate the above-mentioned conventional drawbacks, and have found that a grease composition with extremely excellent water resistance can be obtained by adding together a calcium salt of a fatty acid and a magnesium salt of a fatty acid. Based on this knowledge, we have completed the present invention. That is, the present invention provides (A) a calcium salt of a fatty acid having 12 to 24 carbon atoms (hereinafter referred to as component (A)) and (B) a magnesium salt of a fatty acid having 12 to 24 carbon atoms to 100 parts by weight of the base grease. (Hereinafter referred to as (B) component.)
1.5 parts by weight ≦ (A) + (B) ≦ 5 parts by weight and 0.5 ≦ (A) / (B)
The present invention provides a grease composition in which the additives are added so that the weight ratio is ≦2.0 (weight ratio). In the present invention, the base grease is not particularly limited as long as it consists of a lubricating oil base oil, a metal soap raw material, and various additives such as an antioxidant and a rust preventive agent added as necessary. The lubricating base oil used as the base oil raw material for the base grease is not particularly limited, and in addition to mineral oils such as paraffinic and naphthenic oils, synthetic oils such as diesters and α-olefins can also be used. In addition, the metal soap raw material consists of fatty acids such as stearic acid and 12-hydroxystearic acid, and alkali metals and alkaline earth metals such as aluminum; calcium; sodium, potassium, and lithium, preferably alkali metal hydroxides. It is something. Furthermore, examples of antioxidants include 2,6-di-tertiarybutylparamethylphenol and α-naphthylamine, and examples of rust preventives include Ba-sulfonate. Examples of such base grease include lithium grease, lithium complex grease, calcium grease, calcium complex grease, aluminum complex grease, polyurea grease, etc. In particular, lithium soap grease and lithium-calcium soap grease are used. It is preferable. In the present invention, 1.5 parts by weight of a calcium salt of a fatty acid having 12 to 24 carbon atoms as component (A) and a magnesium salt of a fatty acid having 12 to 24 carbon atoms as component (B) are added to 100 parts by weight of such base grease. part≦(A)＋(B)≦5
It is added in parts by weight such that 0.5≦(A)/(B)≦2.0 (weight ratio). Here carbon number is 12~
Specific examples of the calcium salts of the 24 fatty acids include calcium stearate, calcium oleate, calcium palmitate, calcium myristate, calcium laurate, and calcium behenate, with calcium stearate being particularly preferred. Also (B)
Specific examples of magnesium salts of fatty acids having 12 to 24 carbon atoms used as components include magnesium stearate, magnesium oleate, magnesium palmitate, magnesium myristate, magnesium laurate, magnesium behenate, magnesium linoleate, and linolenic acid. Examples include magnesium, and it is particularly preferable to use magnesium stearate. In the present invention, the above-mentioned components (A) and (B) are used in an amount of 1.5 parts by weight≦component (A)+component (B)≦5 parts by weight, and 0.5≦component (A)/( B) Component≦2.0
(weight ratio), preferably 1.5 parts by weight≦component (A)+component (B)≦0.4 parts by weight, and 0.65≦component (A)/component (B)≦1.6 (weight ratio). Here, (A) component and (B)
If the total amount of the components added is less than 1.5 parts by weight, the resulting grease composition will have lower water resistance at high temperatures and will be more likely to liquefy, which is not preferred. On the other hand, if the total addition amount of components (A) and (B) exceeds 5 parts by weight, the dropping point will be significantly lowered, which is not preferable. Furthermore, if the ratio of component (A)/component (B) is less than 0.5 or more than 2.0, the water resistance at high temperatures will decrease and the composition will become more liquidy, which is not preferable. The grease composition of the present invention is made by adding both base grease components (A) and (B), and is saponified, dehydrated, and gelled with the lubricant base oil and metal soap raw materials that are the raw materials for the base grease. After producing base grease,
A grease composition is produced by adding both components (A) and (B) to the base grease. The grease composition of the present invention exhibits good water resistance not only at room temperature but also at high temperatures, and maintains its grease-like state without liquefying even at high temperatures of 80°C. Moreover, the grease composition of the present invention has an appropriate finished consistency and dropping point, and has improved water resistance. Therefore, the grease composition of the present invention is particularly suitable for use in lubricating bearings of rolling mills in steel mills, ships, automobiles, and other parts where water is likely to enter. Next, the present invention will be explained by examples. Examples 1-9 and Comparative Examples 1-8 6% by weight lithium soap of 12-hydroxystearic acid, base oil feedstock (approximately 92 cst at 40°C)
A basic grease was prepared by a conventional method from 93% by weight of a paraffinic 500 neutral oil having a viscosity of 1% by weight and 1% by weight of an antioxidant (2,6-di-tert-butyl-paramethylphenol). To 100 parts by weight of this basic grease, add calcium salts of various fatty acids having 12 to 24 carbon atoms as component (A) and magnesium salts of various fatty acids having 12 to 24 carbon atoms as component (B) as shown in Table 1. A grease composition was obtained. In addition, for comparison, the above-mentioned (B) component was not added, the addition ratio of both components (A) and (B) was changed, or additives other than the (A) component and (B) component were added. Grease compositions as shown in Table 1 were obtained. For the resulting grease composition, 10% by weight of water
A water-containing roll stability test was conducted at room temperature and at 80°C. The consistency (60w) and dropping point of the obtained grease composition before testing were also measured. The results are shown in Table 1.

【table】

[Table] From the experimental results in Table 1, it is clear that when additives other than ingredients (A) and (B) are used and when calcium stearate is used,
When using 1.5 parts by weight, it maintains a grease-like state at room temperature, but becomes liquid at 80°C.
It turns out that it becomes unusable. When both components (A) and (B) are used, water resistance is further improved than when component (A) is used alone, even if the total amount is the same. In particular, it can be seen that the ratio of (A) component to (B) component is best when it is around 1/1. Furthermore, when both components (A) and (B) are used, even if the total amount is within the range of the present invention, the value of component (A)/component (B) will be
If the value is less than 0.5 or more than 2.0, it becomes liquid at 80℃ and cannot be used. Furthermore, it can be seen that when component (A) + component (B) exceeds 5 parts by weight, the dropping point is extremely reduced.

Claims (1)

[Claims] 1 Based on 100 parts by weight of grease, (A) has 12 or more carbon atoms;
Calcium salt of 24 fatty acids and (B) 12 to 24 carbon atoms
1.5 parts by weight of magnesium salt of fatty acid ≦ (A) + (B)
A grease composition containing ≦5 parts by weight and 0.5≦(A)/(B)≦2.0 (weight ratio). 2. The grease composition according to claim 1, wherein the fatty acid having 12 to 24 carbon atoms is stearic acid. The grease composition according to claim 1, wherein the three-base grease is a lithium grease and/or a lithium complex grease.