JPH023438B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a lithium-based grease composition with an improved composition, and more particularly to a method for producing a lithium-based grease composition with particularly improved wear resistance, high temperature viscosity, and water resistance. Lithium-based greases containing lithium salts of hydroxy fatty acids having 12 to 24 carbon atoms or lithium or calcium salts as thickeners have been widely used for mechanical lubrication. In recent years, lithium-based greases have been developed that co-contain lithium salts of hydroxy fatty acids with 12 to 24 carbon atoms and aliphatic dicarboxylic acids with 2 to 20 carbon atoms, or lithium and calcium salts as thickeners, which improve heat resistance and mechanical properties. It was noted for its excellent stability properties. However, this grease uses dicarboxylic acid, which has poor lubricity, so it has poor lubricity, dicarboxylic acid has poor viscosity at high temperatures, so it has poor high-temperature viscosity, and dicarboxylate salts are highly water-soluble, so it has poor water resistance. In particular, it was recognized that there were also shortcomings in high temperature water resistance. The present inventors conducted research with the aim of improving the drawbacks while maintaining the excellent characteristics of this material, and arrived at the present invention. That is, the present invention comprises a lubricating base oil, (a) a hydroxy fatty acid having 12 to 24 carbon atoms, 1 to 20% by weight, and (b) an aliphatic dicarboxylic acid having 2 to 12 carbon atoms, 0.5 to 20% by weight.
20% by weight (c) A method for producing a lithium-based grease composition containing a dimer acid or a trimer acid having 36 to 54 carbon atoms, 0.3 to 10% by weight of each of the three lithium salts, or lithium and calcium salts. oil base oil and said
The three components (a), (b) and (c) are heated and mixed, and then lithium hydroxide or lithium hydroxide and calcium hydroxide are added as an aqueous solution of 30 to 100% by weight to form a reaction system consisting of a mixture of these. temperature of 65~
While maintaining the temperature at 75°C, the three acid components (a), (b), and (c) are subjected to a silicification reaction with the lithium hydroxide or the base component consisting of lithium hydroxide and calcium hydroxide in one step. A method for producing a lithium-based grease composition, characterized in that the lithium-based grease composition produced by such a production method has all the drawbacks of conventional lithium-based greases and also has its advantages. The inventors of the present invention have obtained a new finding that a lithium-based grease composition that is preserved and is most preferable for mechanical lubrication can be obtained. The most preferred hydroxy fatty acid having 12 to 24 carbon atoms for use in the present invention is 12-hydroxystearic acid, but all other fatty acids may also be used. Other possible uses include 12
-Hydroxylauric acid, 16-hydroxypalmitic acid, etc. can be mentioned. The most preferred aliphatic dicarboxylic acids having 2 to 12 carbon atoms for use in the present invention are sebacic acid and azelaic acid, but all others may also be used. Other substances that can be used include oxalic acid,
malonic acid, succinic acid, glutaric acid, adipic acid,
Examples include pimelic acid, suberic acid, undecanedioic acid, and dodecanedioic acid. Further, as the dimer acid or trimer acid having 36 to 54 carbon atoms that can be used in the present invention, those obtained by heating and polymerizing unsaturated fatty acids such as linoleic acid and oleic acid, and those obtained by bimolecular polymerization include dimer acids having 36 carbon atoms, Trimolecularly polymerized acids are trimer acids having 54 carbon atoms, and any of these can be used. In the present invention, it is suitable to use lithium as the base component to neutralize these acid components, but it is also possible to use a lithium-calcium mixed base component. In the case of this mixed base, water resistance can be further improved. However, if too much calcium component is mixed, the heat resistance will decrease, so the ratio of lithium to calcium should be adjusted to 1:1 or more by weight of lithium hydroxide to calcium hydroxide.
It should stay within the range of 0.1. As the lubricating base oil used in the present invention, refined mineral oils and synthetic oils having lubricating viscosity can be used.
Synthetic oils include diester oils such as dioctyl sebacate, polyester oils such as pentaerythritol tetraester oil, glycol ether oils such as polyoxyethylene-polyoxypropylene block copolymer, and monoolefins having 4 to 20 carbon atoms. Examples include α-olefin polymerized oils such as polymerized oils having an average molecular weight of 300 to 1000, silicone oils such as liquid polymethylsiloxane, and polyphenyl ether oils such as m-bis(m-phenoxyphenoxy)benzene. Grease can be produced by the method of the present invention by reacting a lubricating base oil, three types of acid components, and a base component under specific conditions described below to prepare a grease. In the present invention, the components constituting the lithium-based grease composition include a lubricating base oil, 1 to 20% by weight of a hydroxy fatty acid having 12 to 24 carbon atoms, and 2 to 12 carbon atoms.
Lithium complex grease is mainly composed of 0.5 to 20% by weight of lithium salt or lithium-calcium salt of aliphatic dicarboxylic acid. The weight ratio of 1 to 20:0.5 to 20 constitutes a lithium complex grease. The reason why 0.3 to 10% by weight of a lithium salt or a lithium-calcium salt of a polycarboxylic acid having 36 to 54 carbon atoms is coexisting in the grease composition in addition to the above two components is to mainly compensate for the drawbacks of aliphatic dicarboxylic acids. is the purpose. In other words, it is thought that the good lubricity, high viscosity at high temperatures, and good water resistance attributed to the long chain hydrocarbon groups of dimer acid or trimer acid compensate for all the shortcomings of conventional lithium complex greases. This could be confirmed by experiment. 0.3% by weight of dimer acid or trimer acid
It is not suitable to use less than 10% by weight because it is ineffective and the yield of the grease will be extremely poor. Other additives include rust inhibitors such as petroleum sulfonic acid alkali salts, antioxidants such as salicylic acid alkali salts,
Extreme pressure additives such as zinc dialkyldithiophosphate, dyes can be used. Thus, by using the lithium-based grease composition obtained by the method of the present invention, a lithium-based grease that has not only the excellent heat resistance and mechanical stability of conventional lithium complex greases but also excellent lubricity, high-temperature viscosity, and high-temperature water resistance can be obtained. composition was provided for the first time. The method for producing the lithium-based grease composition of the present invention includes lubricating base oil, (a) 1-20% by weight of hydroxy fatty acid having 12-24 carbon atoms, and (b) 0.5-20% by weight of aliphatic dicarboxylic acid having 2-12 carbon atoms. 20% by weight and (c) 0.3 to 10% by weight of a dimer acid or trimer acid having 36 to 54 carbon atoms are heated and mixed, and then lithium hydroxide or lithium hydroxide and calcium hydroxide are added and saponified. Although it depends on the grease manufacturing method, aliphatic dicarboxylic acids are highly water-soluble, and if the reaction system has a high water content and the temperature of the reaction system is high, more of the aliphatic dicarboxylic acids will dissolve in the water phase and form dicarboxylic acid salts independently. , a lithium-based grease composition that is less likely to form complexes with monocarboxylic acid salts and especially highly oil-soluble dimer acid or trimer acid salts, and has improved lubricity, high-temperature viscosity, and high-temperature water resistance, which are the objects of the present invention. is not obtained. In order to avoid this problem, the present inventors have conducted research and found that the temperature of the reaction system is maintained at a relatively low temperature and the water content of the aqueous solution of lithium hydroxide or lithium hydroxide and calcium hydroxide is reduced as much as possible to form a concentrated solution. We have newly discovered that it is better to reduce the water content of the reaction system as much as possible. That is, the present inventors have found that in order to suitably perform the saponification step of the present invention, the temperature of the reaction system is maintained at 65 to 75°C, and lithium hydroxide or lithium hydroxide and calcium hydroxide are added in an amount of 30 to 100% by weight. As a result of research, they learned that it was necessary to add it as an aqueous solution and saponify it. Here, an aqueous solution of lithium hydroxide or lithium hydroxide and calcium hydroxide with a concentration of 30 to 100% by weight is an aqueous solution of 100% by weight.
This means that the number of grams of lithium hydroxide monohydrate or lithium hydroxide monohydrate and calcium hydroxide contained in each gram is from 30 to 100, and the dispersion state of these alkaline substances in the aqueous solution is It may be present or suspended. Further, the fluid state of the aqueous solution may be liquid or paste. Furthermore, there is no problem even if the aqueous solution has a concentration of 100% by weight and is in the form of a solid powder.
By employing this manufacturing method, the lithium-based grease composition of the present invention having the desired performance can be manufactured. Next, the structure and effects will be specifically shown by Examples 1 to 7 and Comparative Examples 1 to 6 in Tables 1 to 2. The manufacturing method for each example is as follows. Example (1) Add 12-hydroxystearic acid, azelaic acid, dimer acid or trimer acid to base oil as shown in Table 1 and heat to 65-75°C. (2) Add 50% lithium hydroxide aqueous solution or 50% lithium hydroxide-calcium hydroxide mixed aqueous solution at a temperature of 65 to 75℃, react at this temperature for at least 10 minutes, and then quickly raise the temperature. ,
After reacting at 95-120°C for at least 30 minutes,
Immediately raise the temperature to 190-210°C and hold for at least 10 minutes, then cool quickly. (3) After cooling, finish by milling and defoaming. The properties of the grease produced by the above method are shown in Table 1. Comparative Example (1) 12-hydroxystearic acid, azelaic acid, and dimer acid were added to the base oil as shown in Table 2, and the
Heat to 120℃. (2) Add 15% lithium hydroxide aqueous solution at a temperature of 95 to 120℃, react at this temperature for at least 10 minutes, and then quickly raise the temperature to 95 to 120℃.
Immediately after incubating the reactant for at least 30 minutes
Raise the temperature to 190-210°C and hold for at least 10 minutes, then cool quickly. (3) After cooling, finish by milling and defoaming. The properties of the grease produced by the above method are shown in Table 2.

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Claims (1)

[Scope of Claims] 1 Lubricating base oil and (a) hydroxy fatty acid having 12 to 24 carbon atoms, 1 to 20% by weight (b) aliphatic dicarboxylic acid having 2 to 12 carbon atoms, 0.5 to 20% by weight
20% by weight (c) A method for producing a lithium-based grease composition containing a dimer acid or a trimer acid having 36 to 54 carbon atoms, 0.3 to 10% by weight of each of the three lithium salts, or lithium and calcium salts. oil base oil and said
The three components (a), (b) and (c) are heated and mixed, and then lithium hydroxide or lithium hydroxide and calcium hydroxide are added as an aqueous solution of 30 to 100% by weight to form a reaction system consisting of a mixture of these. temperature of 65~
While maintaining the temperature at 75°C, the three acid components (a), (b), and (c) are subjected to a silicification reaction with the lithium hydroxide or the base component consisting of lithium hydroxide and calcium hydroxide in one step. A method for producing a lithium-based grease composition, characterized in that the composition is produced by: