DESC:FIELD OF THE INVENTION:

The present invention deals with calcium sulfonate greases and process for preparation thereof. Particularly, the present invention is directed to calcium sulfonate simple grease, calcium sulfonate complex grease and process for preparation thereof without adding any additional calcium compound such as calcium oxide, calcium hydroxide or calcium carbonate.

BACKGROUND OF THE INVENTION:

Overbased calcium sulfonate greases have been an established grease category for many years. One known process for making such greases is a two-step process involving the steps of “promotion” and “conversion.” Typically the first step (“promotion”) is to react a stoichiometric excess amount of calcium oxide (CaO) or calcium hydroxide (Ca(OH)2) as the base source with an alkyl benzene sulfonic acid, carbon dioxide (CO2), and with other components to produce an oil-soluble overbased calcium sulfonate with amorphous calcium carbonate dispersed therein.

These overbased oil-soluble calcium sulfonates are typically clear and bright and have Newtonian rheology. In some cases, they may be slightly turbid, but such variations do not prevent their use in preparing overbased calcium sulfonate greases. For the purpose of this disclosure, the terms “overbased oil-soluble calcium sulfonate” and “oil-soluble overbased calcium sulfonate” and “overbased calcium sulfonate” refer to any overbased calcium sulfonate suitable for making calcium sulfonate greases. Typically the second step (“conversion”) is to add a converting agent or agents, such as propylene glycol, iso-propyl alcohol, water, formic acid or acetic acid, to the product of the promotion step, along with a suitable base oil (such as mineral oil), to convert the amorphous calcium carbonate to a very finely divided dispersion of crystalline calcium carbonate. Because an excess of calcium hydroxide or calcium oxide is used to achieve overbasing, a small amount of residual calcium oxide or calcium hydroxide may also be present and will be dispersed. The crystalline form of the calcium carbonate is preferably calcite. This extremely finely divided calcium carbonate, also known as a colloidal dispersion, interacts with the calcium sulfonate to form a grease-like consistency. Such overbased calcium sulfonate greases produced through the two-step process have come to be known as “simple calcium sulfonate greases” and are disclosed, for example, in US3242079; US3372115; US3376222, US3377283; and US3492231.

It is also known in the prior art, to combine these two steps by carefully controlling the reaction, into a single step. In this one-step process, the simple calcium sulfonate grease is prepared by reaction of an appropriate sulfonic acid with either calcium hydroxide or calcium oxide in the presence of carbon dioxide and a system of reagents that simultaneously act as both promoter (creating the amorphous calcium carbonate overbasing by reaction of carbon dioxide with an excess amount of calcium oxide or calcium hydroxide) and converting agents (converting the amorphous calcium carbonate to very finely divided crystalline calcium carbonate). Thus, the grease-like consistency is formed in a single step wherein the overbased, oil-soluble calcium sulfonate (the product of the first step “promotion” of the two-step process) is never actually formed and isolated as a separate product. This one-step process is disclosed, for example, in US3661622; US3671012; US3746643; and US3816310.

In addition to simple calcium sulfonate greases, calcium sulfonate complex grease compounds are also known in the prior art. These complex greases are typically produced by adding a strong calcium-containing base, such as calcium hydroxide or calcium oxide, to the simple calcium sulfonate grease produced by either the two-step or one-step process and reacting with stoichiometrically equivalent amounts of complexing acids, such as 12-hydroxystearic acid, boric acid, acetic acid, or phosphoric acid. The claimed advantages of the calcium sulfonate complex grease over the simple grease include reduced tackiness, improved pumpability, and improved high temperature utility. Calcium sulfonate complex greases are disclosed, for example, in US4560489; US5126062; US5308514; and US5338467.

All of the known prior art teaches the use of calcium oxide or calcium hydroxide as the sources of basic calcium for production of calcium sulfonate greases or as a required component for reacting with complexing acids to form calcium sulfonate complex greases. The known prior art generally teaches that the presence of calcium carbonate (as a separate ingredient or as an “impurity” in the calcium hydroxide or calcium oxide, other than the amorphous calcium carbonate dispersed in the calcium sulfonate after carbonation), should be avoided for at least two reasons. The first being that calcium carbonate is generally considered to be a weak base, unsuitable for reacting with complexing acids. The second being that the presence of unreacted solid calcium compounds (including calcium carbonate, calcium hydroxide or calcium oxide) interferes with the conversion process, resulting in inferior grease compounds if the unreacted solids are not removed prior to conversion or before conversion is completed.

US patent no 20130109602 describes compositions using solid calcium carbonate along with the overbased calcium sulfonate, base oil, converting agents and complexing acids for making overbased calcium complex greases. In application US20140121139 A1, solid calcium hydroxyapaptite (mixture of tricalcium phosphate, Ca3(PO4)2, and calcium hydroxide, Ca(OH)2) used as base along with overbased calcium sulfonate, base oil, converting agents and complexing acids for making overbased calcium complex greases.

In US patent 8563488, overbased calcium sulfonate grease has been reported having a water spray off of 40% without use of polymers or their derivatives. Additionally, the prior art does not provide a calcium sulfonate complex grease with both improved thickener yield and dropping point. The known prior art requires an amount of overbased calcium sulfonate of atleast 36% (by weight of the final grease product) to achieve a suitable grease in the NGLI No. 2 category with a demonstrated dropping point of at least 575oF. For example, in prior art (http://www.lubrizol.co.in/IndustrialAdditves/GreaseAdditives/Products/Lubrizol86GR.html), 65-70% of 400 TBN overbased calcium sulfonate LZ86GR is used and resultant greases were reported to have penetration in NLGI grade 2.

All of the known prior art teaches the use of higher concentration of water for preparation of overbased calcium complex greases. For example, in US patent 4560489, 10% water is used for making NLGI grade 2 overbased calcium complex greases.

SUMMARY OF THE INVENTION:

The overbased oil-soluble calcium sulfonate is one of the most expensive ingredients in making calcium sulfonate grease, therefore it is desirable to reduce the amount of this ingredient while still maintaining a desirable level of firmness in the final grease (thereby improving thickener yield). The object of the present invention is to provide, a simplified grease manufacturing process in which there is no requirement of addition of calcium oxide, calcium carbonate or calcium hydroxide and thus saving time and expense associated with additional step.

The present invention further relates to an efficient manufacturing process in which less quantities of water is added for calcite conversion. In present invention only 5% water is required for making NLGI grade 2 greases as shown in Table-1.

Another object of the present invention is to develop a product that can withstand extreme pressure conditions and possesses anti-wear characteristics. It is observed that the composition prepared as per the present invention have inherent superior resistance to water spray off in comparison to similar greases reported in prior art. The developed compositions in present invention have lower values of water spray off as shown in Table-1.

According to one embodiment of the present invention, an overbased calcium sulfonate complex grease composition comprising overbased calcium sulfonate, C12 to C14 alkyl aryl sulfonic acid, water, one or more base oil, one or more converting agent and one or more complexing acid, wherein no additional calcium-containing base is added.

According to another embodiment of the present invention, an overbased calcium sulfonate simple grease composition comprising overbased calcium sulfonate, C12 to C14 alkyl aryl sulfonic acid, water, one or more base oil, and one or more converting agent, wherein no additional calcium-containing base is added.

According to another embodiment of the present invention, a process for preparing an overbased calcium sulfonate complex grease composition comprising the steps of:
(a) adding highly overbased oil soluble calcium sulfonate with suitable amount of base oil to form a homogenous mixture;
(b) adding one or more complexing acid, alkyl aryl sulfonic acid, converting agent and water to the homogenous mixture of step (a);
(c) heating the mixture of step (b) to an elevated temperature;
(d) maintaining the heated mixture of step (c) at the elevated temperature till conversion of amorphous calcium carbonate to finely divided crystalline calcium carbonate,
wherein no additional calcium-containing base is added.

According to another embodiment of the present invention, a process for preparing an overbased calcium sulfonate simple grease composition comprising the steps of:
(a) adding highly overbased oil soluble calcium sulfonate with suitable amount of base oil to form a homogenous mixture;
(b) adding one or more alkyl aryl sulfonic acid, converting agent and water to the homogenous mixture of step (a);
(c) heating the mixture of step (b) to an elevated temperature;
(d) maintaining the heated mixture of step (c) at the elevated temperature till conversion of amorphous calcium carbonate to finely divided crystalline calcium carbonate,
wherein no additional calcium-containing base is added.

Various objects, features, aspects, and advantages of the present invention will become more apparent from the following detailed description of preferred embodiments of the invention.

DETAILED DESCRIPTION OF THE INVENTION:

While the invention is susceptible to various modifications and/or alternative processes and/or compositions, specific embodiment thereof has been shown by way of example in tables and will be described in detail below. It should be understood, however that it is not intended to limit the invention to the particular processes and/or compositions disclosed, but on the contrary, the invention is to cover all modifications, equivalents, and alternative falling within the spirit and the scope of the invention as defined by the appended claims.

The tables and protocols have been represented where appropriate by conventional representations, showing only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having benefit of the description herein.

The following description is of exemplary embodiments only and is not intended to limit the scope, applicability or configuration of the invention in any way. Rather, the following description provides a convenient illustration for implementing exemplary embodiments of the invention. Various changes to the described embodiments may be made in the function and arrangement of the elements described without departing from the scope of the invention.

According to one embodiment of the present invention, an overbased calcium sulfonate complex grease composition comprising overbased calcium sulfonate, C12 to C14 alkyl aryl sulfonic acid, water, one or more base oil, one or more converting agent and one or more complexing acid, wherein no additional calcium-containing base is added.

According to another embodiment of the present invention, an overbased calcium sulfonate simple grease composition comprising overbased calcium sulfonate, C12 to C14 alkyl aryl sulfonic acid, water, one or more base oil, and one or more converting agent, wherein no additional calcium-containing base is added.

According to preferred embodiment of the present invention, the converting agent in the grease composition is selected from the group comprising alcohols, ethers, glycols, glycol ethers.

According to preferred embodiment of the present invention, the complexing acid in the grease composition is selected from the group comprising acetic acid, propanoic acid, butanoic acid and phosphoric acid.

According to preferred embodiment of the present invention, the overbased calcium sulfonate is present in the grease composition in an amount of about 20% to about 50% by weight of the composition.
According to preferred embodiment of the present invention, the overbased calcium sulfonate is present in the grease composition in an amount of about 30% to about 50% by weight of the composition.

According to preferred embodiment of the present invention, the overbased calcium sulfonate is present in the grease composition in an amount of about 35% to about 45% by weight of the composition.

According to preferred embodiment of the present invention, the C12 to C14 alkyl aryl sulfonic acid is present in the grease composition in an amount of about 5% to about 20% by weight of the composition.

According to preferred embodiment of the present invention, the water is present in the grease composition in an amount of about 3% to about 6% by weight of the composition.

According to preferred embodiment of the present invention, the converting agent is present in the grease composition in an amount of about of about 1% to about 4% by weight of the composition.

According to preferred embodiment of the present invention, the complexing acid is present in grease composition in an amount of about 0.2% to about 1% by weight of the composition.

According to preferred embodiment of the present invention, the base oil is present in the grease composition in an amount of about 15% to about 70% by weight of the composition.

According to preferred embodiment of the present invention, the grease composition has a dropping point of 572 ºF or higher.

According to preferred embodiment of the present invention, the grease composition has a total base number (TBN) of about 300 to about 500.
According to preferred embodiment of the present invention, the grease composition has a total base number (TBN) of about 400.

According to another embodiment of the present invention, a process for preparing an overbased calcium sulfonate complex grease composition comprising the steps of:
(a) adding highly overbased oil soluble calcium sulfonate with suitable amount of base oil to form a homogenous mixture;
(b) adding one or more complexing acid, alkyl aryl sulfonic acid, converting agent and water to the homogenous mixture of step (a);
(c) heating the mixture of step (b) to an elevated temperature;
(d) maintaining the heated mixture of step (c) at the elevated temperature till conversion of amorphous calcium carbonate to finely divided crystalline calcium carbonate,
wherein no additional calcium-containing base is added.

According to another embodiment of the present invention, a process for preparing an overbased calcium sulfonate simple grease composition comprising the steps of:
(a) adding highly overbased oil soluble calcium sulfonate with suitable amount of base oil to form a homogenous mixture;
(b) adding one or more alkyl aryl sulfonic acid, converting agent and water to the homogenous mixture of step (a);
(c) heating the mixture of step (b) to an elevated temperature;
(d) maintaining the heated mixture of step (c) at the elevated temperature till conversion of amorphous calcium carbonate to finely divided crystalline calcium carbonate,
wherein no additional calcium-containing base is added.

According to preferred embodiment, the step (b) of the process for preparing the overbased calcium sulfonate grease composition is carried out a temperature below 122 ºF.
According to preferred embodiment, the mixture of step (c) of the process for preparing the overbased calcium sulfonate grease composition is heated to a temperature range of 185 ºF to 195 ºF.

According to preferred embodiment of the present invention, the process for preparing the overbased calcium sulfonate grease composition is further comprising of adding one or more performance additive.

According to preferred embodiment of the present invention, the performance additive is added at a temperature below 194 ºF.

According to preferred embodiment of the present invention, the process for preparing the overbased calcium sulfonate grease composition is further comprising of removal of water and volatile products.

According to preferred embodiment of the process for preparing the overbased calcium sulfonate grease composition of the present invention, the overbased calcium sulfonate is added in range of about 30-50 wt%, alkyl aryl sulfonic acid is added in range of about 5-20 wt%, one or more base oil is added in the range of about 15-70%, water is added in range of about 3-6 wt%, one or more converting agent is added in range of about 1-4 wt% and one or more complexing acid is added in range of about 0.2-1 wt% .

According to one embodiment of the present invention, overbased calcium sulfonate complex grease is obtained having following ingredients by weight; 30%-50% overbased calcium sulfonate, 5%-20% alkyl aryl sulfonic acid, 3%-6% water, 1%-4% converting agents such as alcohols, ethers, glycols, glycol ethers; and one or more complexing acid 0.2%-1.0%, such as acetic acid, phosphoric acid etc.

According to another embodiment of the present invention, water resistant simple calcium sulfonate grease is produced by combining highly overbased oil soluble calcium sulfonate with suitable amount of base oil, then added one or more alkyl aryl sulfonic acid and converting agents such water and alcohol. The mixture was heated to temperature range 185°F to 195°F and maintained under closed condition for conversion of amorphous calcium carbonate to finely divided crystalline calcium carbonate, then rapidly heated to 300°F to 330°F and maintained to remove water and volatile products, then cooled with additional oil added for required consistency. The grease is then milled according to known methods to get a smooth, homogeneous product.

According to one another embodiment of the present invention, calcium sulfonate complex grease with improved resistance to water spray off is produced by adding one or more complexing acids without adding any calcium compound such as calcium oxide, calcium hydroxide or calcium carbonate thus saving time and expense associated with additional step. Complexing acids must be added before conversion process.

When grease produced according to criteria of invention described herein, consistently high quality calcium sulfonate simple or complex greases may be made with having superior resistance to water spray off in comparison to prior art. Softer or harder grades of calcium sulfonate complex grease may be made according to invention by changing to concentrations of overbased calcium sulfonate or alkyl aryl sulfonic acid. Other properties such as load carrying properties, and wear characteristics were also improved according to invention.

According to further embodiment of the present invention, water resistant simple calcium sulfonate grease is produced by reacting and mixing certain components comprising; (a) an overbased calcium sulfonate having amorphous calcium carbonate dispersed therein; (b) a base oil of an appropriate amount to provide desired grease consistency; (c) an appropriate amount of alkyl aryl sulfonic acid added to overbased calcium sulfonate and base oil before conversion; and (d) a converting agent or agents, some or all of which may not be in final product due to high temperature processing. According to this embodiment, no calcium oxide, calcium hydroxide or calcium carbonate is added during grease making thus saving time and the expense associated with the additional processing step and additional ingredients in the prior art methods of producing calcium sulfonate complex greases.

The highly overbased calcium sulfonate used in the embodiments of this invention can be produced in-situ or procured as a commercially available product. These overbased oil soluble calcium sulfonate will have a total base number (TBN) 300 to 500 and most preferably about 400. The amount of highly overbased calcium sulfonate in embodiment of this invention can vary between 20 and 50%. Preferably, the amount of overbased calcium sulfonate in NLGI 2 grease is between 30 to 50% and most probably between 35 to 45%. Test data of five grease batches made using different quantities of 400 TBN overbased calcium sulfonate is given in Table-1. The worked penetration of Example-2 of present invention is within NLGI 2 grade even through percentage of 400 TBN overbased calcium sulfonate is 35%.

Other performance additives described in prior arts may also be added to grease embodiments described in the invention. Such additives can include rust and corrosion inhibitors, metal deactivators, metal passivators, anti-oxidants, extreme pressure additives, anti-wear additives, polymers, tackifiers, dyes, chemical markers and fragrance imparters.

The compositions according to invention are preferably made according to process described herein. This process comprises the following steps: (1) adding and mixing in a suitable grease kettle-a highly overbased oil soluble calcium sulfonate at a temperature that ranges between ambient temperature and about 122°F; (2) adding and mixing one or more converting agents; (3) adding and mixing of complexing acid or acids; (4) slow addition of one or more alkyl aryl sulfonic acids with continuous mixing to avoid frothing and an appropriate amount of suitable base oil; (5) and continue to mixing while heating the mass to 185-194°F and maintained at this temperature till conversion of amorphous calcium carbonate to crystalline form; (6) mixing and heating to sufficiently high temperature for removal of all volatile components; (7) cooling the grease while adding additional oil, if required; (8) adding the performance additives below 194°F, if desired; (9) milling the final grease to obtain final product. Grease can be made in a closed kettle at normal atmospheric pressure or under pressure.

Certain steps of the process are not critical for obtaining preferred grease composition. The temperature at which alkyl aryl sulfonic acids, water, converting agents were added is not critical, but it is preferred that they may be added below 122°F. Addition sequence of complexing acid and alkyl aryl sulfonic is also not critical with respect to each other.

According to one preferred process of making of sulfonate grease, water is removed from the grease after the conversion. Grease is heated quickly to remove the water as soon as possible after conversion is complete. Residual water in grease batch for prolonged duration may result in degradation of thickener yield, dropping point or both. Vacuum may be applied along with heating for quick removal of water. Amount of water used here is less in comparison to other processes where extra water is added for facilitating reaction of complexing acids with calcium bases.

The grease should be heated to temperature sufficiently high to remove the water added for conversion or formed during the chemical reactions during the grease making. Generally, heating temperature will be between 300°F to 380°F, most preferably between 320°F to 350°F.

EXAMPLES

Example-1:
Simple calcium sulfonate grease prepared according to the present invention is as follows: 50 parts by weight of a 400 TBN overbased oil soluble calcium sulfonate was added to a mixing vessel followed by addition of 1.5 parts of converting agent butyl cellosolve. Mixing without heating was done using the planetary paddle. After 10 minutes, 10.0 parts of a primarily alkyl C12-14 aryl sulfonic acid was added slowly with continuous mixing to minimize the frothing and allowed to mix in for 20 minutes. Then 5 parts water was added and mixed for 10 minutes followed by addition of 33.5 parts of group 1 paraffinic base oil having viscosity of 400 cSt at 104°F and allowed to mix for 10 minutes. The mix was heated under closed condition until the temperature reached 185°F. The temperature was held between 185°F and 194°F for 1 hour until Fourier Transform Infrared Spectroscopy (FTIR) indicated the complete conversion of amorphous calcium carbonate to crystallite calcite. Grease vessel was opened and grease was heated to 320oF over 60 minutes with constant mixing and held for 45 minutes at 320°F for dehydration. The heating was removed and vessel was allowed to cool with constant mixing. Cold oil can also be circulated to speed up cooling. When cooled to 194°F, grease was milled through homogenizer to obtain smooth grain free grease. The dropping point of grease was non drop when tested upto 572°F. A dropping point of 464°F was observed after 105x strokes made using grease worker. Only 15% of grease was removed from the test panel when grease tested as per ASTM D-4049. No calcium containing base was added during making of this grease.

Examples-2, 3, 4 & 5:
Greases were made using same process as the Example-1 with inclusion of 0.4 parts of acetic acid as complexing acid and slight variations in quantities of alkyl C12-14 aryl sulfonic acid. Test results of these grease batches are given in Table-1.

Table-1
Components Example no.
Example-1 Example-2 Example-3 Example-4 Example-5
400 TBN oil-soluble calcium sulfonate, parts by weight 50.00 35.00 40.00 45.00 50.00
Butyl cellosolve, parts by weight 1.5 1.5 1.5 1.5 1.5
Alkyl (C12-14) aryl sulfonic acid, parts by weight 10.0 8.4 9.6 10.8 12.0
Acetic acid, parts by weight 0.0 0.4 0.4 0.4 0.4
Water, parts by weight 5.0 5.0 5.0 5.0 5.0
Group 1 paraffinic base oil (400 cst at 104 F), parts by weight 33.5 49.7 43.5 37.3 31.1
Test Test Method Units Results
Penetration
Unworked/worked ASTM
D-217
mm/10 259/264 289/295 274/281 266/272 251/257
Change in penetration after 105X double strokes +9 +7 +11 +13 +8
Dropping Point ASTM
D-2265 oF >572 >572 >572 >572 >572
Dropping Point after 105X double strokes 464 >572 >572 >572 >572
Weld load IP-239 Kg 355 315 315 355 355
Wear scar dia ASTM
D-2266 mm 0.55 0.55 0.55 0.55 0.55
Water spray off ASTM
D-4049 % 15 17 15 13.0 13.0

Examples 6, 7, 8, 9 &10:
Example-6&7 greases were made using same equipments, raw materials, amounts, and manufacturing process as the Example-1 grease, except that the 0.1 and 0.2 parts glacial acetic acid was added respectively as complexing acid prior to conversion but after the alkyl C12-14 aryl sulfonic acid. The dropping points of both greases were non drop upto 572°F. A decrease in dropping point similar to example to Example-1 was observed when Example-6&7 greases were subjected to 105x strokes through grease worker. No calcium containing base was added during making of this grease. Example-8, 9 & 10 grease batches was made using manufacturing process as the Example-6 grease, except that the quantities of complexing acid (glacial acetic acid) were increased gradually. The dropping point was non drop upto 572oF for Example-8, 9 & 10 greases and no change in dropping point was observed when subjected to 105x strokes through grease worker. No calcium containing base was added during making of this grease. All other properties of Example-6, 7, 8, 9 &10 greases were found to be similar as shown in Table-2.

Example 11:
Example-11 grease was made using same equipments, raw materials, amounts, and manufacturing process as the Example-8 grease, except that the glacial acetic acid was added as complexing acid prior to conversion and addition of alkyl C12-14 aryl sulfonic acid. The final grease had unworked penetration and dropping point similar to Example-8 grease.

Table-2
Components Example no.
Example-6 Example-7 Example-8 Example-9 Example-10
400 TBN oil-soluble calcium sulfonate, parts by weight 50.00 50.00 50.00 50.00 50.00
Butyl cellosolve, parts by weight 1.5 1.5 1.5 1.5 1.5
Alkyl (C12-14) aryl sulfonic acid, parts by weight 10.0 10.0 10.0 10.0 10.0
Acetic acid, parts by weight 0.1 0.2 0.4 0.6 1.0
Water, parts by weight 5.0 5.0 5.0 5.0 5.0
Group 1 paraffinic base oil (400 cst at 104 F), parts by weight 33.4 33.3 33.1 32.9 32.7
Test Test Method Units
Results
Penetration
Unworked/worked ASTM
D-217
mm/10 259/264 259/267 259/265 263/269 267/271
Change in penetration after 105X double strokes +9 +11 +8 +11 +9
Dropping Point ASTM
D-2265 oF >572 >572 >572 >572 >572
Dropping Point after 105X double strokes 472 482 >572 >572 >572
Weld load IP-239 Kg 355 355 355 355 355
Wear scar dia ASTM
D-2266 mm 0.55 0.55 0.55 0.55 0.55

Example 12:
To demonstrate the effect of addition of complexing acids after conversion a grease batch (Example-12) was prepared similar to Example-8 grease, except that 0.4% acetic acid was added just after the conversion but before dehydration. The composition of this grease was identical to the composition of Example-8 grease. Although the penetration of the Example-12 grease was comparable to Example-8 & 11 greases, the dropping point of Example-12 grease was nearly 200oF lower than Example-8 & 11 greases as shown in Table-3.

Table-3
Characteristics Example-8 Grease Example-11 Grease Example-12 Grease
Composition Shown in Table-2 Similar to Example-8 Similar to Example-8
Complexing acid addition process complexing acid added prior to conversion but after the alkyl C12-14 aryl sulfonic acid complexing acid added prior to conversion and addition of alkyl C12-14 aryl sulfonic acid Similar to Example-8 grease except that complexing acid added just after the conversion but before dehydration
Penetration
Unworked/worked, ASTM D-217 259/265 262/268 264/267
Dropping Point, oF
ASTM D-2265 >572 >572 372

Any commonly used oil such as petroleum based naphthenic and paraffinic and well known in grease prior art may be used according to the present invention. Synthetic base oils such as polyalpha-olefins (PAO), diesters, polyol esters, Polyalkyl glycol (PAG) and alkylated aromatics may be used in making of greases according to invention. In some cases, synthetic oils can interfere with conversion process of grease making according to this inversion as will be understood by those of ordinary skill of grease making. In such cases, synthetic oil should be added after conversion process to minimize the adverse effects. Petroleum based naphthenic and paraffinic base oils are preferred due to lower cost and easy availability. The base oil may be added before conversion, or after evaporation of volatile components to achieve desired consistency. The total amount of base oil added will typically between 30 to 60% and most probably 35 to 50% for NLGI 2 grease, based on the final weight of grease.

Examples 13-15:
Three grease batches identical to Example-8 grease were made except having different quantities of butyl cellosolve were added before conversion. As can be seen from Table-4, the amount of butyl cellosolve must be added most preferably 1.5 to 3.5%. One or more converting agents, such as alcohols, alkoxy ethers, glycols, glycol polyethers, organic acids, inorganic acids must be added prior to conversion. The amount of such converting agents added, based on the final weight of greases can be between 1.0 to 5%, and converting agents with lower boiling points such as butyl cellosolve, isopropyl alcohol are preferred, so that they may remove easily after conversion. Organic and inorganic acids may also serving as converting agents in addition to complexing.

Table-4
Components Example no.
Example-8 Example-13 Example-14 Example-15
400 TBN oil-soluble calcium sulfonate, parts by weight 50.00 50.00 50.00 50.00
Butyl cellosolve, parts by weight 1.5 2.0 2.5 3.5
Alkyl (C12-14) aryl sulfonic acid, parts by weight 10.0 10.0 10.0 10.0
Acetic acid, parts by weight 0.4 0.4 0.4 0.4
Water, % by weight 5.0 5.0 5.0 5.0
Group 1 paraffinic base oil (400 cst at 104 F), % by weight 33.1 32.6 32.1 31.1
Test Test Method Units Results
Penetration
Unworked/worked ASM
D-217
mm/10 259/265 263/269 259/267 263/271
Change in penetration after 105X double strokes +8 +11 +10 +12
Dropping Point ASTM
D-2265 oF >572 >572 >572 >572

Examples 16-21:
Water is added in amount 2.5 to 10%, most preferably between 4 to 6%, based on the final grease. Six grease batches were made that were identical to Example-8 grease except different quantities of water added before conversion and the amount of time grease maintained at 185-194oF before increasing the temperature to remove the water. Table-5 provides the details of these batches. As can be seen from the data of these batches, the best combination of thickener yield and working stability is obtained by using between about 4 to 6% water and keeping the calcite conversion time around 60 minutes.
Table-5
Components/ Characteristics Example no.
Example-16 Example-17 Example-8 Example-18 Example-19 Example-20 Example-21
Water, % by weight 4.0 5.0 5.0 5.0 7.5 7.5 10
Time grease maintained at 185-194 F (minutes) 60 30 60 120 60 120 60
Unworked/worked Penetration , mm/10 ASTM D-217 262/267 259/263 259/265 262/275 263/272 271/279 267/273
Change in penetration after 105X double strokes + 10 +12 +8 +18 +15 +17 +17
Dropping Point, oF,
ASTM D-2265 >572 >572 >572 >572 >572 >572 >572

Examples 22-25:
Four grease batches identical to Example-8 were made except different heating time from conversion temperature to dehydration temperature and test data of these batches are given in Table-6. Best thickener yield and working stability is obtained when heating time is around 60-90 minutes. Thickening efficiency and working stability decreased when heating time is more than 60-90 minutes as can be seen from Example-24 & 25.

Table-6
Components/ characteristics Example no.
Example-22 Example-8 Example-23 Example-24 Example-25
Heating time from conversion temperature to dehydration temperature (minutes) 30 60 90 120 150
Unworked/worked Penetration , mm/10 ASTM D-217 262/265 259/265 263/272 275/279 285/287
Change in penetration after 105X double strokes +15 +8 +5 +17 +17
Dropping Point, oF,
ASTM D-2265 >572 >572 >572 >572 >572

Examples 26-28:
Three grease batches were made that were identical to Example-8 grease except different quantities of alkyl C12-14 aryl sulfonic acid were added before conversion. As can be inferred from the data of these batches given in Table-7, thickening efficiency and resistance to water spray off improved with increasing quantities of alkyl aryl sulfonic acid. However, larger wear scar dia were observed in grease batches having more than 15% alkyl aryl sulfonic acid as shown in Example-27 & 28. Alkyl aryl sulfonic acids must be added in an amount 5 to 25%, preferably 10 to 15%, based on the weight of finished grease. One or more alkyl aryl sulfonic acids having alkyl chain length typically between 8 to 16 carbons must be added prior to conversion according to embodiment for obtaining water resistant greases. Such acids typically referred as alkyl benzene or alkyl naphthalene sulfonic acids and are commercially available. Converting agents should be added before addition of alkyl aryl sulfonic acids to promote reactivity. Water must be added after the adding and reacting alkyl aryl sulfonic acids to avoid frothing. There is no need to add additional calcium compounds for reaction with alkyl aryl sulfonic acids as calcium bases are already dispersed in matrix of overbased calcium sulfonate.

Table-7
Components Example no.
Example-26 Example-8 Example-27 Example-28
400 TBN oil-soluble calcium sulfonate, % by weight 50.00 50.00 50.00 50.00
Butyl cellosolve, % by weight 1.5 1.5 1.5 1.5
Alkyl (C12-14) aryl sulfonic acid, % by weight 5.0 10.0 15.0 20.0
Acetic acid, % by weight 0.4 0.4 0.4 0.4
Water, % by weight 5.0 5.0 5.0 5.0
Group 1 paraffinic base oil (400 cst at 104 F), % by weight 38.1 33.1 28.1 23.1
Test Test Method Units Results
Penetration
Unworked/worked ASTM
D-217
mm/10 285/292 259/265 235/243 205/205
Change in penetration after 105X double strokes +11 +8 +14 +23
Dropping Point ASTM
D-2265 oF >572 >572 >572 >572
Weld load IP-239 Kg 315 355 355 355
Wear scar dia ASTM
D-2266 mm 0.55 0.55 0.60 0.80
Water spray off ASTM
D-4049 % 22 18 15 12

Examples 29-33:
To demonstrate the effect of polymers on grease characteristics, two types of commercially available polyisobutylene (PIB) polymers K-Vis 200 (2000 molecular weight from M/s Kothari Petrochemcials) and K-Vis 10 (1000 molecular weight from M/s Kothari Petrochemcials) were used. Four grease batches were made similar to Example-8 grease except, different quantities of K-Vis 200 & K-Vis 10 were added when grease mass cooled to 248oF during cooling stage. Detailed composition and test data of these batches is given in Table-8. Extreme pressure and water resistance properties improved significantly with inclusion of high molecular weight PIB polymers. As can be seen from Table-8, a weld load of 700 kg was obtained in Example-32 grease where 20% K-Vis 200 was used. Example-32 grease also showed excellent resistance to water spray off as only 5% grease was removed in ASTM D 4049 test. Example-33 grease was made similar to Example-32 except the following change: PIB polymer having molecular weight less than 1000 was added in place of 2000 molecular weight PIB polymer used in Example-32. Except weld load, all other characteristics of Example-33 grease were found to identical to Example-32 grease. A weld load of 355 Kg was obtained indicating no improvement in extreme pressure characteristics with low molecular weight PIB polymer. Slightly increased wear scar dia were obtained when PIB polymers were used as shown in Table-8.

Table-8
Components Example no.
Example-29 Example-30 Example-31 Example-32 Example-33
400 TBN oil-soluble calcium sulfonate, % by weight 50.00 50.00 50.00 50.00 50.00
Butyl cellosolve, % by weight 1.5 1.5 1.5 1.5 1.5
Alkyl (C12-14) aryl sulfonic acid, % by weight 10.0 10.0 10.0 10.0 10.0
Acetic acid, % by weight 0.4 0.4 0.4 0.4 0.4
Water, % by weight 5.0 5.0 5.0 5.0 5.0
PIB polymer, 2000 molecular weight, (K-Vis 200), % by weight, K-Vis-200 5.0 10.0 15.0 20.0 0.0
PIB polymer, 1000 molecular weight, (K-Vis 10), % by weight, K-Vis-10 0.0 0.0 0.0 0.0 20.0
Group 1 paraffinic base oil (400 cst at 104 F), % by weight 28.1 23.1 18.1 13.1 13.1
Test Test Method Units Results
Penetration
Unworked/worked ASTM
D-217
mm/10 263/269 266/272 263/270 259/262 262/269
Change in penetration after 105X double stroke +11 +9 +8 +7 +8
Dropping Point ASTM
D-2265 oC >572 >572 >572 >572 >572
Weld load IP-239 Kg 355 355 500 700 355
Wear scar dia ASTM
D-2266 mm 0.60 0.65 0.65 0.65 0.65
Water spray off ASTM
D-4049 % 10 8 5 5 8

Summarizing thus far, these examples taken together strongly demonstrate the following: (1) over based calcium sulfonate-based complex greases can be prepared without addition of calcium containing bases; (2) greases having excellent resistance to water spray off can be prepared compared to prior art greases and, and excellent water resistance can be achieved without any addition of polymers. (3) Water resistance can be further improved with addition of polymers, and greases having very high weld loads can be prepared with addition of addition of high molecular weight PIB polymers.

Example 34:
Example-34 grease demonstrates how the present invention can be applied to prepare grease composition useful for hot roll mills of steel plants. It was made as follows: 40 parts by weight of a 400 TBN overbased oil soluble calcium sulfonate was added to a mixing vessel followed by addition of 1.5 parts of converting agent butyl cellosolve. Mixing without heating was done using the planetary paddle. After 10 minutes, 8.0 parts of a primarily alkyl C12-14 aryl sulfonic acid and 0.4 parts glacial acetic acid were added slowly with continuous mixing to minimize the frothing and allowed to mix in for 20 minutes. Then 5 parts water was added and mixed for 10 minutes followed by addition of 25.1 parts of group 1 paraffinic base oil having viscosity of 400 cSt at 104oF and allowed to mix for 10 minutes. The mixed was heated under closed condition until the temperature reached 185°F. The temperature was held between 185°F and 194°F for I hour for the conversion of amorphous calcium carbonate to crystallite calcite. Grease vessel was opened and grease was heated to 320°F over 60 minutes with constant mixing and held for 45 minutes at 320oF for dehydration. The heating was removed and vessel was allowed to cool with constant mixing. Cold oil can also be circulated to speed up cooling. When cooled to 248°F, 20 parts of commercially available PIB polymer (K-Vis 200) having molecular weight 2000 was added and mixed properly. When cooled to 194°F, 1 parts of commercially available rust inhibitor additive (NA-SUL BSN from M/s King Industries) was added, mixed properly and milled through homogenizer to obtain smooth grain free grease. Several lab batches were made according to the above procedure and tested. The average results of those tests are given in Table-9.

Table-9
Composition and test Data of Example-33 calcium sulfonate grease
Components Composition
(% by weight)
400 TBN oil-soluble calcium sulfonate 45.0
Butyl cellosolve 1.5
Alkyl (C12-14) aryl sulfonic acid 8.0
Acetic acid 0.4
Water 5.0
Group 1 paraffinic base oil (400 cst at 104° F) 19.1
PIB polymer, 2000 molecular weight, (K-Vis 200) 20.0
NA-SUL BSN 1.0
Test Method Result
Consistency, 1/10 mm
Unworked
60 Strokes
105X Strokes ASTM D-217
285
288
304
Dropping Point, °F ASTM D-2265 >572
Rust Preventive, rating ASTM D-1743 Pass
EMCOR IP 220 0, 0
Copper Corrosion ASTM D-4048 1 A
Weld load, Kg IP-239 700
Wear Scar Dia, mm ASTM D-2266 0.65

Although the examples provided herein fall primarily in the NLGI No. 2 or No. 3 grade, it should be further understood that the scope of this present invention includes all NLGI consistency grades harder and softer than a No. 2 grade. However, for such greases according to the present invention that are not NLGI No. 2 grade, their properties should be consistent with what would have been obtained if more or less base oil had been used so as to provide a No. 2 grade product, as will be understood by those of ordinary skill in the art.

As used herein, “thickener content” applies to the concentration of the highly overbased oil-soluble calcium sulfonate required to provide grease with a specific desired consistency as measured by the standard penetration tests ASTM D 217 or D 1403 commonly. Similarly used herein the “dropping point” of grease shall refer to the value obtained by using the standard dropping point test ASTM D 2265 commonly used in lubricating grease manufacturing.

As used herein, quantities of ingredients identified by percentages or parts are by weight during grease manufacturing, even though the some ingredient (such as water, alcohols) may or may not be present in the final grease in the quantity identified for addition as an ingredient. Those of ordinary skill in the art will appreciate upon reading this specification, including the examples contained herein, that modifications and alterations to the composition and methodology for making the composition may be made within the scope of the invention and it is intended that the scope of the invention disclosed herein be limited only by the broadest interpretation of the appended claims to which the inventor is legally entitled.
,CLAIMS:We Claim:
1. An overbased calcium sulfonate complex grease composition comprising:
(a) overbased calcium sulfonate;
(b) C12 to C14 alkyl aryl sulfonic acid;
(c) water;
(d) one or more base oil;
(e) one or more converting agent; and
(f) one or more complexing acid,

wherein no additional calcium-containing base is added.

2. An overbased calcium sulfonate simple grease composition comprising:
(a) overbased calcium sulfonate;
(b) C12 to C14 alkyl aryl sulfonic acid;
(c) water;
(d) one or more base oil; and
(e) one or more converting agent,
wherein no additional calcium-containing base is added.

3. The grease composition of claim 1 or 2, wherein converting agent is selected from the group comprising alcohols, ethers, glycols, glycol ethers.

4. The grease composition of claim 1, wherein the complexing acid is selected from the group comprising acetic acid, propanoic acid, butanoic acid and phosphoric acid.

5. The grease composition of claim 1 or 2, wherein the overbased calcium sulfonate is present in an amount of about 20% to about 50% by weight of the composition.

6. The grease composition of claim 5, wherein the overbased calcium sulfonate is present in an amount of about 30% to about 50% by weight of the composition.
7. The grease composition of claim 6, wherein the overbased calcium sulfonate is present in an amount of about 35% to about 45% by weight of the composition.

8. The grease composition of claim 1 or 2, wherein the C12 to C14 alkyl aryl sulfonic acid is present in an amount of about 5% to about 20% by weight of the composition.

9. The grease composition of claim 1 or 2, wherein the water is present in an amount of about 3% to about 6% by weight of the composition.

10. The grease composition of claim 1 or 2, wherein the converting agent is present in an amount of about 1% to about 4% by weight of the composition.

11. The grease composition of claim 1, wherein the complexing acid is present in an amount of about 0.2% to about 1% by weight of the composition.

12. The grease composition of claim 1 or 2 having a dropping point of 572 ºF or higher.

13. The grease composition of claim 1 or 2 having a total base number (TBN) of about 300 to about 500.

14. The grease composition of claim 13 having a total base number (TBN) of about 400.

15. The grease composition of claim 1 or 2, wherein the base oil is present in an amount of about 15% to about 70% by weight of the composition.

16. A process for preparing an overbased calcium sulfonate complex grease composition comprising the steps of:
(a) adding highly overbased oil soluble calcium sulfonate with suitable amount of base oil to form a homogenous mixture;
(b) adding one or more complexing acid, alkyl aryl sulfonic acid, converting agent and water to the homogenous mixture of step (a);
(c) heating the mixture of step (b) to an elevated temperature;
(d) maintaining the heated mixture of step (c) at the elevated temperature till conversion of amorphous calcium carbonate to finely divided crystalline calcium carbonate,

wherein no additional calcium-containing base is added.

17. A process for preparing an overbased calcium sulfonate simple grease composition comprising the steps of:
(a) adding highly overbased oil soluble calcium sulfonate with suitable amount of base oil to form a homogenous mixture;
(b) adding one or more alkyl aryl sulfonic acid, converting agent and water to the homogenous mixture of step (a);
(c) heating the mixture of step (b) to an elevated temperature;
(d) maintaining the heated mixture of step (c) at the elevated temperature till conversion of amorphous calcium carbonate to finely divided crystalline calcium carbonate,

wherein no additional calcium-containing base is added.

18. The process for preparing the overbased calcium sulfonate grease composition of claim 16 or 17 wherein step (b) is carried out a temperature below 122 ºF.

19. The process for preparing the overbased calcium sulfonate grease composition of claim 16 or 17 wherein the mixture of step (c) is heated to a temperature range of 185 ºF to 195 ºF.

20. The process for preparing the overbased calcium sulfonate grease composition of claim 16 or 17 further comprising of adding one or more performance additive.

21. The process for preparing the overbased calcium sulfonate grease composition of claim 20 wherein the performance additive is added at a temperature below 194 ºF.

22. The process as claimed in claim 16 or 17 further comprising of removal of water and volatile products.

23. The process as claimed in claim 16 or 17, wherein the overbased calcium sulfonate is added in range of about 30-50 wt%, alkyl aryl sulfonic acid is added in range of about 5-20 wt%, one or more base oil is added in the range of about 15-70%, water is added in range of about 3-6 wt%, one or more converting agent is added in range of about 1-4 wt% and one or more complexing acid is added in range of about 0.2-1 wt%.