JPS6149358B2 - - 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 that require frequent braking, the frictional heat caused by braking can cause the temperature to rise to 150°C to 180°C.
Temperatures exceeding ℃ 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, the present invention binds acetic anhydride, adipic acid, sebacic acid, and azelaic acid to substantially all of the hydroxyl groups of 12-hydroxystearic acid and hydroxy fatty acids of castor hydrogenated oil to a base oil of mineral oil or synthetic oil, thereby forming carboxyl groups and glycerin. This is a high dropping point lithium soap grease characterized by containing lithium bonded to the ester portion as a thickener. The present inventor utilized the reactivity of hydroxyl groups in fats and oils to react almost all of the hydroxyl groups in fats and oils with acetic anhydride, a lower organic acid, and adipic acid, sebacic acid, and azelaic acid, which are dibasic acids. After esterifying the hydroxyl groups, the remaining fatty acids and the fatty acid groups in the glycerin ester portion were saponified with lithium hydroxide to bind lithium, which was used as a thickener, and it was discovered that a lithium soap grease with a high dropping point could be obtained. It was. As a method for measuring the amount of hydroxyl groups in fats and oils, a method is known in which acetyl chloride or acetic anhydride is reacted with the hydroxyl groups in fats and oils in the presence of pyridine, etc. In the present invention, the amount of hydroxyl groups in fats and oils is also measured. When reacting with acids, it is effective to use metal oxides such as titanium oxide, pyridine, cyanide, etc. as catalysts for the purpose of promoting the reaction. In order to further improve the heat resistance of the grease of the present invention, it is more effective to use hydroxystearic acid in combination with a linear higher fatty acid such as stearic acid or a branched fatty acid 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, non-hydrocarbon oils, ester oils such as dibasic acid esters, silicate esters, phosphate esters, neopentyl polyol esters, and polyalkylene oils. Polyglycol oils such as coal, polyphenyl ether oils, polyolefin oils, 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. Acetic anhydride is effective as the lower organic acid to be reacted with the hydroxyl group of the hydroxy acid, and adipic acid, sepacic acid, and azelaic acid are effective as the dibasic acids 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, lower organic acid, and dibasic acid. The present invention will be explained in detail below by specifically showing examples. Example 1 Combination of raw materials used Hydrogenated castor oil 15.1% by weight Acetic anhydride 2.5 〃 Lithium hydroxide 2.0 〃 Mineral oil lubricating oil (SAE20, VI100) 79.4 〃 Antioxidant (aromatic amine) 1.0 〃 11.7 in 50 parts of mineral oil lubricating oil Part of castor hydrogenated oil and 0.7
An aqueous solution of acetic anhydride of 1.0 m 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 Lithium 12-hydroxystearate
11.6% by weight Adipic acid 2.3 〃 Mineral oil lubricating oil (SAE20, VI100) 85.1 〃 Antioxidant (aromatic amine) 1.0 〃 50 parts mineral oil lubricating oil, 11.6 parts lithium 12-hydroxystearate, 2.3 parts adipic acid and Water is placed in an autoclave reactor and heated while stirring. Be careful not to exceed the temperature of 200℃ and the pressure of 8.0Kg/ ^cm2 . When the temperature reaches 200℃, start degassing and remove moisture. Next, add the remaining 35.1 parts of mineral lubricating oil, rapidly cool it, stir vigorously, and heat it again to 190℃.
raise it to After that, let it cool to 100℃ and antioxidant 1.0
After adding 30% and mixing well, apply a disper mill. Example 3 Combination of raw materials used Lithium 12-hydroxystearate
11.6% by weight Sebacic acid 3.2 Mineral lubricating oil (SAE20, VI100) 84.2 Antioxidant (aromatic amine) 1.0% by weight The manufacturing method was carried out according to Example 2. Example 4 Combination of raw materials used Lithium 12-hydroxystearate
12.0% by weight Azelaic acid 3.1 〃 Mineral oil lubricating oil (SAE20, VI100) 83.9 〃 Antioxidant (aromatic amine) 1.0 〃 The manufacturing method was carried out according to Example 2. In the case of Example 1, lithium 12-hydroxystearate is produced from the reaction between the carboxy group of hydroxy fatty acid and lithium hydroxide. The ratio is calculated as x=14.78 from 15.1/938=x/3×306, so 14.78% by weight of lithium 12-hydroxystearate is produced. The molar ratio of this 14.78% by weight lithium 12-hydroxystearate to acetic anhydride was 14.78/306:2.5/102=1:0.507. 1 mole of acetic anhydride decomposes to produce 2 moles of acetic acid groups, each of which is bonded to the hydroxyl group of lithium 12-hydroxystearate, so almost all of the hydroxyl groups of lithium 12-hydroxystearate are bonded to the acetate group. There is. Similarly, Examples 2, 3, 4
In Example 2, the molar ratio of lithium 12-hydroxystearate to adipic acid, sebacic acid, and azelaic acid is calculated as follows: 11.6/306:2.3/146.15=1:0.
415 In Example 3, 11.6/306:3.2/202.25=1:0.
417 In Example 4, 11.6/306:3.1/188.23=1:0.
It is 420. Lithium 12-hydroxystearate has one hydroxyl group in one molecule, adipic acid, sebacic acid,
Azelaic acid has two carboxyl groups in one molecule.
Almost all of the hydroxyl groups of lithium 12-hydroxystearate are bonded to the carboxyl groups of each acid. 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】

[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. Acetic anhydride, adipic acid, sebacic acid, or azelaic acid is bonded to substantially all of the hydroxyl groups of 12-hydroxystearic acid or hydroxyl fatty acids of castor hydrogenated oil to a base oil of mineral oil or synthetic oil to form carboxyl groups and glycerin esters. A high dropping point lithium soap grease characterized by containing lithium bound as a thickener in its parts.