JPS6149359B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a lithium soap grease with a high dropping point, and relates to a novel high-quality lithium soap grease composition that exhibits little change in consistency at high temperatures and also maintains excellent oxidation stability and water resistance. It is. Lithium soap grease is widely used as a general-purpose grease because it has no noticeable drawbacks in general applications. Among these, a particularly useful one is one using lithium hydroxystearate as a thickener, which maintains excellent mechanical stability and water resistance, and is widely used at temperatures below 120°C. However, as usage conditions become harsher and the temperature at which it is used rises, conventional lithium soap grease softens and bleeds out, making it unsatisfactory in terms of heat resistance. For example, in cars equipped with disc brakes near the wheel bearings, when driving in hilly or mountainous areas where braking is often required, the frictional heat generated by braking can reach temperatures of 150℃ to 180℃.
Temperatures above these levels are no longer rare, and conventional lithium soap grease lacks heat resistance and runs the risk of staining disc brakes due to softening and leakage. Another example is the lubrication of hot air ventilator bearings. In this case as well, the temperature inside the bearing may rise to 150°C to 200°C, and the dropping point
Lithium soap greases below 200°C can no longer be used for the lubrication of this type of bearing. In order to improve this situation, research has been conducted to improve the heat resistance of lithium soap grease so that it does not flow even at temperatures of 150°C or higher, and numerous patents have been published. For example, higher fatty acids such as stearic acid and 12-hydroxystearic acid are combined with dibasic acids such as azelaic acid and sebacic acid (US Pat. Nos. 2,896,296, 2,937,993, 3,223,633,
3791973) and combinations of lithium salts of higher fatty acids with boric acid, phosphoric acid esters, and lithium salts (U.S. Patent Nos. 2872417 and 3988248).
(Japanese Special Publication No. 53-37082) Furthermore, lithium salts of higher fatty acids are combined with lithium salts and esters of aromatic carboxylic acids (U.S. Patent No. 53-37082).
No. 3929651, No. 3758407), etc. have been announced.
These are called lithium complex greases and are said to have a dropping point of 250°C or higher. However, although these lithium complex greases have high dropping points, it has been found that they have a major drawback in that they become nearly liquid at temperatures below 200°C and flow out from inside the bearing. The present invention aims to solve these problems by paying particular attention to these points, and as a result of intensive studies by the inventor, it has been found that the present invention has a high dropping point and little change in consistency at high temperatures. The company has developed a new high-quality, high-dropping-point grease composition with excellent shear stability, water resistance, and oxidation stability. That is, in the present invention, the base oil of mineral oil or synthetic oil contains as a thickening agent, boric acid or phosphoric acid is bound to the hydroxyl group of hydroxy fatty acid, and lithium is bound to the carboxyl group and glycerin ester part. This is a high dripping point lithium soap grease. The present inventor took advantage of the reactivity of hydroxyl groups in fats and oils to react a part of the hydroxyl groups in fats and oils with an inorganic acid such as boric acid or phosphoric acid, esterified the hydroxyl groups in fats and oils, and then They discovered that a lithium soap grease with a high dropping point could be obtained by saponifying the fatty acid and fatty acid groups of the glycerin ester moiety with lithium hydroxide to bond lithium as a thickener. A known method for measuring the amount of hydroxyl groups in fats and oils is to use acetyl chloride or acetic anhydride in the presence of pyridine or the like to react with hydroxyl groups in fats and oils.
In the present invention, it is also effective to use metal oxides such as titanium oxide, pyridine, cyanide, etc. as catalysts for the purpose of promoting the reaction between hydroxyl groups in fats and oils and various acids. In order to further improve the heat resistance of the grease of the present invention, straight chain higher fatty acids such as stearic acid are added to hydroxystearic acid.
It is even more effective to use a combination of branched fatty acids such as itstearic acid. The base oil components used in the present invention are hydrocarbon oils and synthetic lubricating oils derived from petroleum and having a lubricating oil viscosity that have been conventionally refined, solvent refined and hydrocracked or hydrofinished. Synthetic lubricating oils include hydrocarbon oils such as ethylene and propylene polymerized oils and non-hydrocarbon oils, ester oils such as dibasic acid esters, silicate esters, phosphate esters, neopentyl polyol esters, and polyalkylene glycols. Polyglycol oils, polyphenyl ether oils, polyolefin oils, etc.
Silicone oils and halocarbon oils such as chlorofluorocarbon oils can be used as base oils. As the hydroxy fatty acid used as a raw material for the thickener used in the present invention, 12-hydroxystearic acid, which is obtained by hydrogenating castor oil and has one hydroxyl group in the molecule, and hydroxy fatty acid from hydrogenated castor oil can be used. 12-Hydroxystearic acid is a saturated fatty acid obtained by hydrogenating ricinoleic acid, which contains 80 to 85% of castor oil, and has one hydroxyl group in the molecule. Boric acid or phosphoric acid is effective as an inorganic acid to be reacted with the hydroxyl group of the hydroxy acid. Lithium hydroxide is used as the metal for saponifying the reaction product of the hydroxy fatty acid and the inorganic acid. The present invention will be explained in detail below by specifically showing examples. Example 1 Combination of raw materials used Hydrogenated castor oil 11.7% by weight Boric anhydride 0.7 〃 Lithium hydroxide 1.6 〃 Mineral oil lubricating oil (SAE20, VI100) 85.0 〃 Antioxidant (aromatic amine) 1.0 〃 50 parts of mineral oil lubricating oil 11.7 parts hydrogenated castor oil and 0.7 parts
Part of an aqueous solution of boric anhydride is placed in an autoclave reactor and heated with vigorous stirring. pressure
While maintaining the temperature at 5.0Kg/cm ² , raise the temperature to 180℃ to allow the two to fully react. Next, add the remaining 35 parts of mineral lubricating oil and lower the temperature, then add 1.6 parts of an aqueous solution of lithium hydroxide, heat again, and degas at 160°C to remove moisture. After that, increase the temperature further to a maximum heating temperature of 190.
After holding at ℃ for a while, let it cool. Add 1.0 part of antioxidant at 100℃, mix well, and apply a disper mill. Example 2 Combination of raw materials used Hydrogenated castor oil 11.8% by weight Boric anhydride 0.2 Lithium hydroxide 1.6 Mineral oil lubricating oil (SAE20, VI100) 85.4 Antioxidant (aromatic amine) 1.0 11.8 parts of hydrogenated castor oil 0.2 parts of boric anhydride 20
% aqueous solution and methanol, and stir and heat to 150°C in an autoclave reactor. Pressure is 5Kg/cm ²
Be careful not to exceed. Next, 85.4 parts of mineral oil lubricating oil was added and the temperature was lowered, and then 1.6 parts of an aqueous solution of lithium hydroxide was added, heated again, and degassed at 160°C to completely remove water and methanol. after that
Heat to 180℃, hold for a while, then release. 100℃
Add 1.0 part of antioxidant and mix well, then apply a disper mill. Example 3 Combination of raw materials used Hydrogenated castor oil 12.0% by weight Phosphoric anhydride 0.9 Lithium hydroxide 1.6 Mineral oil lubricating oil (SAE20, VI100) 84.5 Antioxidant (aromatic amine) 1.0 The manufacturing method is as in Example 1 I followed the instructions. Example 4 12-Hydroxystearic acid 11.2% by weight Boric anhydride 0.7 〃 Lithium hydroxide 1.6 〃 Mineral oil lubricant (SAE20, VI100) 85.5 〃 Antioxidant (aromatic amine) 1.0 〃 Production method according to Example 1 I did it. The properties of Examples 1 to 4 above are shown in Table 1 in comparison with the properties of commercially available lithium soap grease.

[Table] As shown in the above results, the grease according to the present invention has a high dropping point, shows little change in consistency at high temperatures, maintains excellent oxidation stability and miscibility stability, and has a low degree of oil separation. It is a new quality lithium soap grease. Since the high dropping point lithium soap grease according to the present invention has the above-mentioned advantages, it can be used in applications that cannot be satisfied with conventional greases, and is extremely practical and has a wide range of applications.

Claims (1)

[Claims] 1 Mineral oil or synthetic base oil, boric acid or phosphoric acid bound to the hydroxyl group of hydroxyl fatty acid of 12-hydroxystearic acid or castor hydrogenated oil, and lithium bound to the carboxyl group and glycerin ester part. A high dropping point lithium soap grease characterized by containing it as a thickener.