FORM-2
THE PATENTS ACT, 1970
(39 of 1970)
AND
THE PATENTS RULES, 2003 COMPLETE SPECIFICATION
(See Section 10; Rule 13)
1. TITLE OF THE INVENTION:
"Lithium Complex Grease Manufacturing Process."-
2. APPLICANT:
(a) NAME: STANDARD GREASES & SPECILLITIS PRIVATE
LIMITED.
(b) NATIONALITY: AN INDIAN COMPANY
(c) ADDRESS: 101, Ketan Apartments,
233, R. B. MehtaMarg, Ghatkopar-East, Mumbai-400 077, MAHARASHTRA, INDIA.
The following specification describes the nature of the invention and the manner in which it is to be performed:-

3. PREAMBLE TO THE DESCRIPTION
The following process particularly describes the invention and the manner in which it is to be performed.
Field of Invention
Lithium complex grease manufacturing process. Background of the Invention & the Related Art
Majority of dynamic machine operations run on bearings, gears, joints etc. which need grease for lubrication. Historically, the utilization of grease to lubricate a wheel and axle occurred just after the discovery of the wheel. The first universal greases were crude forms of lime mixed with vegetable oils/animal fats. These classes of grease continued to be used for almost all kinds of applications requiring lubrication until the industrial revolution.
However, in the last few decades, a remarkable progress has been made in terms of machine design. This has affected the operating parameters and thus the requirements for lubricating greases. As operating parameters like speed, load, temperature, etc., vary significantly based upon the equipment, it is practically impossible for a single grease to handle all the diversified applications. Consequently, a large number of lubricating greases have been developed, resulting in large number of greases in the market.
Lubricating greases basically are composed of thickener, base oil and performance additives. Worldwide lithium/lithium complex, calcium, sodium, aluminum/aluminum complex, calcium sulfonate complex, polyurea, synthetic/specialty etc. lubricating greases are available. However, today the most popular greases worldwide are lithium based greases.

In modern machinery design and construction, machines are required to operate under more and more severe conditions with the expectation of increased productivity and less downtime. This has made it difficult for the normal lithium greases to satisfactorily fulfill these requirements. Hence, the need was felt for & is met by more efficient high-performance greases like lithium-complex, calcium-sulfonate complex, aluminum complex, polyurea and clay-based greases. However, because of their good high temperature capability, good water resistance, good structural stability, good response to various additives and good compatibility with other greases lithium greases and lithium-complex greases are used in maximum quantity.
Lithium complex greases generally possess good shear stability, high-temperature characteristics and water-resistance properties. Other performance requirements like extreme pressure, anti-wear, rust and corrosion inhibition can further be improved by adding suitable additives. The best property of lithium complex greases is that they have higher dropping points, allowing the greases to be used at higher temperatures. The dropping point of lithium complex greases is higher due to the presence of a second thickener component, known as the complexing agent.
Mechanical stability, also known as shear stability, is the ability of grease to maintain consistency when subjected to shear forces. The lithium complex greases show a good resistance to shear. This property makes lithium complex greases popular for use in a wide range of applications.
As described earlier, the lithium complex greases are popular for high temperature applications especially in the steel plants where the operating conditions are most severe. For wide temperature applications, lithium complex greases are also prepared using synthetic oils such as Poly Alpha Olefin, Oil Soluble Polyalkylene Glycol etc. Traditionally, lithium complex greases are prepared by using various complexing agents such as boric acid, dibasic acids etc. Among the dibasic acids, sebacic acids & azelaic acids are most commonly used in making of lithium complex greases. The

lithium complex greases prepared using sebacic acid or azelaic acids in synthetic hydrocarbon have similar physical properties. The cost of these acids keeps on varying and plays a vital role in the selection for the use as complexing agent.
It was observed that lithium complex greases having high dropping points, good extreme properties and very satisfactory water resistance properties can be prepared e by employing borate esters/borate esters-amine complexes in lithium hydroxy fatty acid soap thickened greases. It appears on the basis of IR and other evidence that a stable co-ordinated compound is formed by electron sharing between the boron atom of the borate ester compound and hydroxyl group of the hydroxy fatty acid soap, which accounts for the high dropping point of lithium complex greases.
The advent of Boron Esters as complexing agents has made the lithium complex grease making process very simple, less time consuming as well as economical. The commercial boron esters are recommended in lithium base greases prepared using 12 hydroxy stearic acid (12 HSA). These boron esters are added at the final stage of the process before homogenization and at temperatures below 90°C, like any other performance additives. Thus, the presence of boron esters is not required in the cooking stage and is added at the end of the manufacturing stage before homogenization/milling like other performance additives.
The boron esters employed to raise the dropping point of the lithium greases are compounds of alkyl or aryl borates or aliphatic amines which form borate ester adducts or complexes. The borate esters added to lithium base greases form lithium borates & change the dropping point of the lithium base greases. The, change in the dropping point of the lithium base greases varies depending upon the type of lithium borate formed i.e. monolithium borate, dilithium borate or trilithium borate or mixture of these borates. It has been established that presence of dilithium borate in the lithium base greases increases its dropping point to the maximum extent. The presence of lithium phosphate also plays a role in boosting the dropping point of the lithium base greases.

US Patent 4,435,299 and US Patent 3,988,248 describe the lithium complex grease composition using hydroxyl fatty acids, lithium tetra borate and lithium phosphate.
US Patent 4,781,850 describes a grease composition where in a major portion is lithium soap prepared from 12 Hydroxy Stearic Acid (12 HSA) and minor amount of borated catachol. The lithium soap so prepared and borated catachol are used in such proportion that increases the dropping point of the grease to appreciable amount.
US Patent 4,802,999 describes the composition of lithium complex grease obtained by using hydroxyl fatty acids & lithium phosphate and dilithium borate. The said lithium complex grease has high dropping point, superior oxidation stability and longer life.
US Patent 3,912,639, US Patent 3,565,802 and US Patent 4,401,580 describe greases with or without lithium borate or without lithium phosphate.
All these patents describe in their examples a process of lithium complex grease preparation using hydroxyl fatty acids & borate esters to get the high dropping point. None of these patents give the process of making lithium complex grease using hydrogenated castor oil (HCO). Further, the batch cycle time of preparing the lithium complex grease using 12 HSA is more, as in this case saponification is generally carried out in open kettle as compared to the batch cycle time of preparing the lithium complex grease using HCO wherein saponification is invariably carried out in pressure vessel. Further, it is observed that, the mechanical stability of the lithium complex grease prepared by using 12 HSA is poorer as compared to the one prepared by using HCO.
Keeping the above in mind, a need was felt to develop a process of preparing lithium complex grease using HCO having required high dropping point and better mechanical stability. Also, the process which is having a shorter batch cycle time and is cost saving.

4. DESCRIPTION OF THE INVENTION
The present invention describes a process of obtaining high dropping point lithium complex greases using hydrogenated castor oil as fat and lithium hydroxide monohydrate. The complexing agents used are boron esters of alkyl/aryl alcohols or boron ester-amine complexes. The dropping point obtained with this process is almost as high as that obtained with 12 hydroxy stearic acid. Also, the lithium complex grease so obtained has a better mechanical stability. Similarly, the process by which lithium complex grease is made has a shorter batch cycle time and is cost saving
Following examples illustrate use of HCO and various base oils in the processes of manufacturing lithium complex grease keeping the boron ester constant i.e. alkyl borate ester:
Example 1:
In a grease kettle of 4 Kg. capacity, 600 gm of paraffinic oil with viscosity of 110 cSt at 40 °C and VI of 90 is added. Then 240 gm of Hydrogenated Castor Oil (HCO) was added. Further, the charge was heated to 80°C to dissolve the Hydrogenated Castor Oil (HCO). Then, 36 gm of lithium hydroxide was made into slurry in water and slowly added to the charge at 80°C. Herein, one needs to take precaution that, the charge is not over flown from the kettle. Hence, the addition of lithium hydroxide is required to be done slowly with vigorous stirring. After complete addition of lithium hydroxide, the charge is slowly heated to 130-140°C at the rate of 5°C rise in approximately 10 minutes with constant stirring at rpm of 10-60. The heating needs to be continued till all the water from the charge evaporates and the mass becomes totally dehydrated. Need to check the alkalinity at this stage and to adjust the same at 0.05 to 0.5 % by addition of lithium hydroxide or stearic acid as required. After adjusting the alkalinity start heating the charge at rate of 10°C in 15 minutes. Raise the temperature to 190-195°C and maintain the same temperature for half an hour.

Then, switch off heat and start the addition of the remaining oil slowly. Maintain the base oil viscosity at VG-220 level by proper addition of light oil and heavy oil. Further, cool the charge between 160-100°C and add the alkyl borate ester in a range between 1-5% of the total charge. After addition of the boron ester, the charge is mixed for half an hour and then brought to 70° C & milled through milling machine and tested for the dropping point as per ASTM D-2265 test method. The dropping point obtained is 279°C.
Example 2:
Under this example except the base oil used all other ingredients as well as the process of manufacture is the same as for example 1 above. The base oil herein used is a blend of naphthenic oils light and heavy with a viscosity of 217 cSt at 40°C and VI of 33. The grease when tested for dropping point as per ASTM D-2265, the dropping point obtained was 280°C.
Example 3
Under this example except the base oil used all other ingredients as well as the process of manufacture is the same as for example 1 above. The oil used is blend of polyalpha olefin oils of light viscosity and heavy viscosity with final viscosity of 232 cSt at 40 °C and VI of 149. The grease when tested for dropping point as per ASTM D-2265, the dropping point obtained was 262°C.
Example 4
Under this example except the base oil used all other ingredients as well as the process of manufacture is the same as for example 1 above. The oil used was blend of light and heavy Oil Soluble Polyglycol(OSP). The final viscosity of the blend was 236.5 cSt at 40° C and VI of 216. The dropping point of the grease was tested as per ASTM D 2265 & the same was at 272°C.

Table 1 gives the dropping point of all the examples.
Table 1

Tests Example 1 Example2 Example3 Example4
Dropping point, °C ASTM D-2265 279 280 262 272
In the following examples, boron ester was changed. The boron ester used was boron ester-amine complex. In all the following examples the other ingredients are the same & the process of manufacture is also same. In place of alkyl borate, borate ester-amine complex was used. The process of grease manufacturing was same.
Example 5:
Under this example the boron ester used is borate ester-amine complex. All other ingredients as well as the process of manufacture is the same as for example 1 above. The base oil herein used is paraffinic oil with viscosity of 110 cSt at 40 °C and VI of 90. The grease when tested for dropping point as per ASTM D-2265, the dropping point achieved was at 275°C.
Example 6:
Under this example the borate ester used is borate ester-amine complex. All other ingredients as well as the process of manufacture is the same as for example 1 above. The base oil herein used is a blend of naphthenic oils light and heavy with a viscosity of 217 cSt at 40°C and VI of 33. The grease when tested for dropping point as per ASTM D-2265, the dropping point achieved was at 272°C.
Example 7

Under this example except the base oil used all other ingredients as well as the process of manufacture is the same as for example 1 above. The oil used is blend of polyalpha olefin oils of light viscosity and heavy viscosity with final viscosity of 232 cSt at 40 °C and VI of 149. The grease when tested for dropping point as per ASTM D-2265, the dropping point achieved was at 279°C.
Example 8
Under this borate ester used is boron ester-amine complex except the base oil used all other ingredients as well as the process of manufacture is the same as for example 1 above.-The oil used was blend of light and heavy Oil Soluble Polyglycol(OSP). The final viscosity of the blend was 236.5 cSt at 40° C and VI of 216. The dropping point of the grease was tested as per ASTM D 2265 & the same was at 270°C.
Table 2 gives the dropping point of all the examples.
Table 2

Tests Example 5 Example 6 Example 7 Example 8
Dropping point, °C ASTMD-2265 275 272 279 270
It is noteworthy that, other than above two boron esters other boron esters like Boron Amide- Imide complex also were used and similar range bound results relating to the dropping points were observed.
Apart from having a high dropping point, the lithium complex grease prepared using this method & hydrogenated castor oil give better mechanical stability and roll stability. It also gives better water absorption properties. Following examples illustrate the same:

Example 9- A lithium complex grease was prepared using the developed process and HCO and alkyk borate. It was fortified with conventional extreme pressure, antiwear, corrosion inhibitor and anti oxidant additives. The base oil used was a paraffinic oil of VG-100 Grade. The grease was tested for mechanical stability and roll stability. The results of the same are as depicted in Table 3 below:
Table 3

Tests Test Method Lithium complex Grease with HCO Example 9
Mechanical stability, difference between 60 strokes and 100,000 strokes penetration, units ASTMD-217 18
Roll Stability, 100 Hrs. room temperature, % change ASTMD-1831 11.4
The mechanical stability and roll stability are much superior as compared to the lithium grease prepared with 12 hydroxy stearic acid where the mechanical stability and roll stability figures observed are 28 units and 18 % respectively.
Lastly, the water resistance properties of the lithium complex grease prepared using the process under consideration were tested. The process of preparing lithium complex grease with HCO also leads to lithium complex grease with better water absorption properties than the one prepared with 12 HSA using conventional procedure. Following example illustrates the same.
Example 10-

The lithium complex grease was prepared as in example 9 above. The grease was tested for 60 strokes penetration and 10,000 strokes penetration. The same grease was then mixed with 10% water and again subjected to 10,000 stroke penetration. The difference in penetration values for 10,000 penetration with and without water was only +1 unit. This indicates that the said process and lithium complex grease with hydrogenated castor oil gives better water absorption properties.
5. We claim:
1. A Process of preparing lithium complex greases having a dropping point >260°C using Hydrogenated Castor Oil (HCO) as fat and alkyl borate ester and ZDDP as in example 1 wherein the base oil is paraffinic with viscosities ranging from 2.0 cSt to36.0 cSt at 100°C.
2. A process of preparing lithium complex grease using Hydrogenated Castor Oil (HCO) as fat and alkyl borate ester and naphthenic oil with viscosities ranging from 2 to 40 cSt and Viscosity Index of negative to +60
3. A process of preparing lithium complex grease using Hydrogenated Castor Oil (HCO) as fat and alkyl borate ester and polyalpha olefin as base oil with a viscosity of 6 cSt to 100 cSt at 100°C and VI of 120-160.
4. A process of preparing lithium complex grease using Hydrogenated Castor Oil (HCO) as fat and alkyl borate ester and Oil Soluble Polyglycol as base oil with a viscosity of 2 cSt to 40 cSt at 40°C and VI of 120-160.
5. A process of preparing lithium complex grease using HCO as fat and boron ester of following formula:

Rn B(XR')m And Rn (BXB)(XR')m'
Where R is hydrocarbon or substituted hydrocarbon group
R' is hydrogen or hydrocarbon group or substituted hydrocarbon group.
X- Oxygen or Sulphur
n- whole number from 0 to 2
n'-whole number from 0 to 3
m- whole no. from 1 to 3
m'- whole no. from 0 to 4
The said lithium complex greases have better mechanical stability, better roll stability and better water absorption properties.