CN115968398A

CN115968398A - High performance grease composition containing renewable base oil

Info

Publication number: CN115968398A
Application number: CN202180036522.5A
Authority: CN
Inventors: A·库马尔
Original assignee: Chevron USA Inc
Current assignee: Chevron USA Inc
Priority date: 2020-04-22
Filing date: 2021-04-20
Publication date: 2023-04-14
Also published as: CA3180654A1; EP4139426A1; JP2023523000A; CO2022016604A2; AU2021261736A1; MX2022013121A; BR112022021409A2; WO2021214641A1

Abstract

The present invention relates to high performance grease compositions based on renewable base oils. The compositions disclosed in this invention with or without performance additives describe superior antiwear properties, anti-friction properties, thermal and oxidative stability, high temperature long life, low noise, low thickener content, better dispersancy in renewable base oils compared to the same grease compositions prepared with conventional mineral and synthetic base oils. Grease compositions formed from renewable base oils are useful for bearings and gears in automotive, industrial, and marine applications.

Description

High performance grease composition containing renewable base oil

Technical Field

The present invention relates for the first time to the development of new grease compositions based on different thickeners in renewable base oils and methods therefor. The superior performance characteristics of these new grease compositions with and without performance additives have been compared to greases also prepared in conventional mineral and synthetic base oils.

Background

Overbased calcium sulfonates were reported in the 1940 s primarily as additives for corrosion protection and oxidation in engine oils. Overbased calcium sulfonates (OBCS) were reported in the 1960 s as thickeners for greases and were prepared essentially in conventional mineral and/or synthetic base oils such as PAO. These OBCS greases require over >50% thickener content to achieve the desired consistency and therefore lack sufficient base oil for lubrication. Such reported greases have low drop points and therefore have limited high temperature application capability, poor cold weather flow and stability problems. Thus, these fully formulated greases are not as characteristic as the lithium complex greases that are currently popular, and are also significantly more expensive, and therefore do not draw sufficient attention.

In 1985, muir et al (US No. 4,560,489) disclosed a new process and composition for preparing overbased calcium sulfonate complex (OBCSC) based greases containing colloidally dispersed calcium carbonate in the form of crystalline calcite, calcium borate and a calcium soap of a soap-forming aliphatic monocarboxylic acid containing at least 12 carbon atoms, such as 12-hydroxystearic acid. The grease compositions disclosed in the present invention are prepared in mineral oil or synthetic base oil derived from mineral oil, such as PAO. The unique compositions and methods disclosed in this invention result in lower thickener levels due to compounding, high drop point, extreme pressure, water resistance, and rust prevention characteristics. This has led to the widespread use of these (OBCSC) greases in industry, particularly in high temperature, heavy duty and aqueous applications. The performance characteristics of such OBCSC greases are reported to be superior to the most popular lithium complex greases.

More recently, overbased calcium sulfonate base greases have seen exponential growth in a wide range of applications (NLGI production survey). The growing potential cause of these greases is attributed to the uncertainty in the supply of lithium, an important component in the manufacture of lithium-based greases because of their increasing use in lithium batteries in electronic products and electric vehicles. The increase in lithium cost reduces the price balance between lithium complex greases and calcium sulfonate greases, resulting in an increased interest in calcium sulfonate greases. Recent publications and articles indicate that calcium sulfonate greases may be a potential replacement for lithium based greases.

There is an increasing demand for environmentally friendly lubricants and greases for use in environmentally sensitive applications such as mining, agriculture, rail, manufacturing and marine. Different countries have different labeling protocols and regulatory compliance to promote biodegradable or renewable oil-based lubricants. In marine applications, the use of marine universal licenses (VGPs) for grease may be mandated in the near future. Greases based on plants and their synthetic esters have been widely reported. Thickeners used to formulate such environmentally friendly/biodegradable greases are mainly based on lithium, calcium, aluminum complexes and clay-based thickeners. The growing major challenge of these biodegradable greases as compared to the corresponding mineral or synthetic oils (e.g., PAO-based greases) is their inherently inferior performance.

On the other hand, efforts to date to formulate high performance biodegradable/renewable oil-based overbased calcium sulfonate greases comparable to mineral or synthetic PAO-based greases have not been very successful. One of the challenges facing formulators is that newtonian overbased calcium sulfonates, unlike mineral oil/synthetic PAOs, tend to react with vegetable oils or esters derived from such oils due to their polarity and composition during the gelling/conversion step and at elevated temperatures. This inhibits the conversion of amorphous calcium carbonate to its crystalline calcite form, which is an essential step in the gelling process. However, due to certain expected inherent properties thereof, namely high temperature, extreme pressure and anti-wear, water resistance and rust prevention, there is a strong need to develop environmentally friendly overbased calcium sulfonate greases that are comparable to mineral or synthetic base oils.

In general, the high performance characteristics of greases are characterized by their ability to perform at high temperatures (> 250 ° f), under heavy duty conditions, in humid environments, protecting equipment from rust and corrosion. Patents and reports described in the following embodiments show that these greases are very limited in scope and do not become truly high performance multi-purpose. The calcium sulphonate greases reported so far in the following technical solutions are soft semi-fluid greases which are not suitable for bearing applications or have been thickened to the desired consistency with the aid of other supporting thickeners, such as solid lubricants, waxes or other known conventional thickeners.

Grease compositions based on calcium sulphonate based thickeners and biodegradable base oils, such as polyol esters or polyalkylene glycols, are disclosed in us 2004/0235679 A1. This patent discloses a semi-fluid in NLGI 00/000 composition with specific gravity >1.0 for marine applications, where the lubricant is immersed in water when dispensed on water, avoiding surface gloss, and is biodegradable when immersed in water, claiming to be an eco-friendly lubricant. In a preferred embodiment, 10-20% calcium sulfonate is used, along with other additives, to form a semi-fluid type lubricant that is within the NLGI 00 consistency range according to ASTM D217 and has a penetration range of 400-430, and does not disclose any other performance characteristics of the resulting grease other than the desired performance characteristics. In general, for any bearing application, a grease of at least NLGI 1 consistency is required, and thus the present disclosure is not used for the purpose of high performance bearing greases.

Us patent No. 2011/0111995A 1 discloses a grease composition containing a complex of calcium sulfonate and a wax, preferably carnauba wax, in a ratio of biodegradable oil and water of (1. In embodiment 1, calcium sulfonate greases were prepared using a combination of mineral or synthetic oils and biodegradable oils, where the biodegradable oil was the problematic polyalphaolefin oil or XHVI oil. In this patent publication, although the use of biodegradable oils is mentioned, the base oil used is used in combination with mineral or synthetic oils, and the resulting properties of the grease are not explicitly intended for lubrication purposes.

US 5,338,467 discloses a method of forming a non-newtonian oil composition in the form of a grease comprising overbased calcium sulfonate and colloidally dispersed solid particles of calcium carbonate in the form of calcite, the method comprising heating in an oleaginous medium a conversion agent of overbased calcium sulfonate, amorphous calcium carbonate and a fatty acid comprising twelve to twenty-four carbon atoms. The oil used is mineral oil.

US 7,294,608 B2 discloses a calcium sulfonate grease composition using a calcium sulfonate complex thickener, a solid lubricant using synthetic, mineral and/or vegetable oils and as other performance enhancing additives for thread oils. The vegetable oil used in the composition may be seed-based or of animal origin. However, the preparation of calcium sulfonate complex greases in vegetable or renewable oils is not described in the detailed embodiments.

US 8,618,028 B2 discloses grease thickener compositions based on mixed calcium sulphonates and lithium-based soaps in mineral oils, synthetic oils, vegetable oils and combinations thereof as fire-resistant fluids, wherein commercially available calcium sulphonates are used as one component. This patent does not disclose any compositional details for making calcium sulfonate greases in vegetable/biodegradable/renewable oils. Sagar et al (International Journal of Recent Technologies in Mechanical and Electrical Engineering, vol.4, no. 4, pp.1-5, 2017) reported the synthesis of calcium sulfonate greases in soybean oil. In the disclosed process, soybean oil is mixed with 300TBN sulfonate, calcium carbonate and oleic acid in a beaker and the mixture is stirred continuously until a cream colored solution is obtained. The solution was placed in a pre-heated oven at 100 ℃ for 15 minutes. Acetic acid is added, which is reported to act as a catalyst. The mixture was then heated at 180 ℃ for 20 minutes, followed by the addition of calcium hydroxide and boric acid. The mixture was further heated to 200 ℃ and maintained for 60 minutes. The final product is reported to have a greasy mix. Alternative manufacturing methods using alternative heating techniques, such as microwaves, have also been proposed. The cone penetration of the final product is reported to be 284, NLGI 2 consistency, but the drop point is low, 105 ℃, and as the drop point of the final product is much lower than the commonly known calcium sulphonate grease, it does not find much use in today's harsh industrial environment.

Calcium sulphonate grease compositions and methods of making them reported in the prior art are prepared from blends of base oils, one of which may be a mineral or synthetic base oil, such as PAO. Alternatively, the calcium sulphonate grease is prepared with the aid of well known thickeners, such as solid lubricants, calcium carbonate, waxes or soap thickeners. The main challenge in the manufacture of calcium sulfonate greases in these renewable oils is that during the gelation or conversion of newtonian overbased calcium sulfonates to non-newtonian overbased calcium sulfonates, the reactants tend to react with the base oil by themselves and require the conversion of amorphous calcium carbonate to crystalline calcite because the necessary step of thickening does not occur adequately. Thus, the compositions disclosed in the prior art (whether a combination of base oils, or a combination of other known thickeners) are used to meet the desired consistency.

Disclosure of Invention

One embodiment of the present invention is a non-newtonian high performance overbased calcium sulfonate complex (OBCSC) grease composition prepared in a renewable base oil as described herein.

Another embodiment is a grease composition based on a combination of overbased calcium sulfonate complexes, lithium, aluminum complexes, clay-based or polyurea and Renewable Base Oil (RBO) and no performance additives. These RBO grease compositions exhibit superior performance in terms of life, antiwear, antifriction, oxidation resistance, low noise characteristics, high temperature and high pressure characteristics when compared to the same greases prepared in minerals (600N and 600R) and PAO 8.

Another embodiment is a zinc-free antiwear grease composition in a renewable base oil.

Drawings

Fig. 1 is a four-ball wear versus friction coefficient plot according to method ASTM D2266 for a lithium-based grease prepared in PAO 8.

Fig. 2 is a four ball wear versus friction coefficient plot of SynNova renewable base oil as described herein according to method ASTM D2266.

Detailed Description

Overbased calcium sulfonate greases have become recognized greases in the state of the art. US 9,273,265 teaches that the known process for making such greases is a two-step process comprising "boosting" and "converting" steps. Typically, the first step ("boosting") is to react a stoichiometric excess of Calcium Oxide (CO) or calcium hydroxide (Ca (OH) 2) as an alkali source with alkylbenzene sulfonic acid, carbon dioxide (CO 2), and with other components to produce an oil-soluble overbased calcium sulfonate having 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 hazy, but such changes do not prevent their use in preparing overbased calcium sulfonate greases.

Typically, the second step ("conversion") is the addition of one or more converting agents, such as propylene glycol, isopropanol, water, formic acid or acetic acid, and a suitable base oil (such as mineral oil) to the product of the promoting step to convert the amorphous calcium carbonate to a very finely divided crystalline calcium carbonate dispersion. Because excess calcium hydroxide or calcium oxide is used to achieve overbasing, small amounts of residual calcium oxide or calcium hydroxide may also be present and will be dispersed. The crystalline form of calcium carbonate is preferably calcite. This extremely finely divided calcium carbonate, also referred to as a colloidal dispersion, interacts with the calcium sulfonate to form a grease-like consistency. Such overbased calcium sulfonate greases produced by a two-step process are referred to as "simple calcium sulfonate greases" and are disclosed, for example, in U.S. Pat. nos. 3,242,079; nos. 3,372,115; nos. 3,376,222; U.S. Pat. No. 3,377,283; and U.S. Pat. No. 3,492,231.

Additionally, US 4,560,489 teaches methods and compositions for preparing overbased calcium sulfonate complex (OBCSC) based greases by complexing simple overbased calcium sulfonates by in situ reaction of one or more inorganic and/or organic acids.

There is an increasing demand for high performance greases based on renewable base oils, particularly in environmentally sensitive applications. These high performance requirements are typically extreme pressure and antiwear, high temperature, rust and corrosion protection, water resistance, thermal and oxidative stability, and the like. Typically, these environmentally friendly/biodegradable greases are prepared in vegetable oils or their synthetically derived esters. These base oils are essentially esters/glycerides of long chain fatty acid derivatives, as compared to hydrocarbon-based non-renewable mineral and synthetic base oils. The fundamental difference between these non-renewable minerals and their synthetically derived base fluids, such as Polyalphaolefins (PAO), is that these oils are essentially non-polar, whereas plant and synthetic esters derived from plant/animal sources are polar in nature, which makes a large difference when overbased calcium sulfonates are formulated in these fluids.

Taught herein is a two-step process for promoting and converting the formation of a grease composition based on the above, wherein a renewable base oil is used in the conversion step for preparing an overbased calcium sulfonate complex grease composition.

Another embodiment is a grease composition containing the renewable base oil described herein as a component of a thickener, in which overbased calcium sulfonate complexes, lithium, aluminum complexes, clay bases, or polyureas are used, without the use of performance additives that exhibit superior performance in terms of service life, antiwear, anti-friction, oxidation resistance, low noise characteristics, high temperature and high pressure characteristics when compared to the same greases prepared in minerals (600N and 600R) and PAO 8.

Another embodiment is a zinc-free antiwear grease composition in a renewable base oil. OBSC grease compositions may require at least 1% zinc-based anti-wear additives (ZDDP), particularly when the OBSCs and lithium-based greases are prepared in mineral oil/synthetic PAO oils.

Different grease compositions are prepared based on overbased calcium sulfonate complex, lithium, aluminum complex or clay-based greases in renewable oils alone or in combination with ester-based oils, mineral oils, PAOs. For comparison, the same thickener-based grease compositions were also prepared in mineral and synthetic oils.

For the purposes 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 use in making calcium sulfonate greases. The overbased calcium sulfonate content of the greases as produced by the methods described herein and as shown by the illustrative specific examples set forth below may be up to 65%, depending on the preferred hardness of the grease. In general, grease application rates range from NLGI 000 (fluid type grease used in gears) to NLGI 3 (harder). NLGI 000-NLGI 0 grades are for gears, while NLGI 1-3 are for bearing applications. NLGI 000 grease can be as low as 10%, and for NLGI 3 grease it may rise up to about 65%. In particular, up to 40% is suitable for NLGI #2 grease-medium hardness.

Additionally, as disclosed herein, the term "additive" refers to a substance that does not participate in the grease reaction process and remains suspended in the grease matrix and is added to meet certain performance characteristics.

Renewable base oil component of a grease composition

Renewable base oils for use in the present invention are understood to be derived from biological resources used to make greases and include the hydrocarbon mixtures described below. Such base oils may be made from biological organisms designed to make a particular oil, but are not so limited, but do not include petroleum distillation process oils, such as non-limiting example mineral oils. A suitable method for assessing renewable content is by ASTM D6866-12, "standard test method for determining biobased content of solid, liquid, and gas samples using radioactive carbon analysis.

The renewable base oils described herein and shown by the illustrative specific examples set forth below may be present up to about 85%, typically in the 85% weight range. In particular, with reference to the above NLGI grease, the base oil may be about 85% for an NLGI 000 grease containing 10% thickener, and as low as 30% for an NLGI 3 grease where the thickener claims to be 65%.

Another embodiment is to use a renewable base oil, otherwise referred to herein as "SynNova 9", having the following hydrocarbon structure and characteristics:

the unique branched structure of the hydrocarbon mixtures disclosed herein is characterized by NMR parameters such as BP, BI, internal alkyl branching, and 5+ methyl. The BP/BI of the hydrocarbon mixture is in the range of ≧ 0.6037 (internal alkyl branching per molecule) + 2.0. The 5+ methyl groups of the hydrocarbon mixture are on average 0.3 to 1.5 per molecule.

Based on the carbon number distribution, the hydrocarbon mixture can be divided into two carbon ranges, C28 to C40 carbons, and greater than or equal to C42. Typically, about or greater than 95% of the molecules present in each hydrocarbon mixture have a carbon number within a specified range. Representative molecular structures in the C28 to C40 range can be proposed based on NMR and FIMS analysis. Without wishing to be bound by any one particular theory, it is believed that the structures made by oligomerization and hydroisomerization of olefins have methyl, ethyl, butyl branches distributed throughout the structure, and that the branch index and branch proximity contribute to the surprisingly good low temperature properties of the product. An exemplary structure in this hydrocarbon mixture is as follows:

the hydrocarbon mixture exhibits:

KV100 in the range of 3.0-10.0 cSt;

pour point range of-20 to-55 ℃;

so that Noack is at 2750 (-CCS at 35 ℃ C.) ^(-0.8) (ii) relationship of Noack between + -2 and CCS at-35 ℃;

the relationship of Noack to CCS for the hydrocarbon mixture is shown in figures 3 and 4. In each figure, the top line represents Noack =2750 (-CCS at 35 ℃) ^(-0.8) +2 and bottom graph represents Noack =2750 (-CCS at 35 deg.C) ^(-0.8) -2. More preferably, the Noack of the hydrocarbon mixture is related to the CCS at-35 ℃ such that the Noack has a relationship of Noack =2750 (CCS at-35 ℃) ^(-0.8) +0.5 and Noack =2750 (-CCS at 35 ℃) ^(-0.8) -2. Hydrocarbon mixtures closer to the origin in fig. 3 and 4 have been found to be more advantageous for low viscosity engine oils due to low volatility and reduced viscosity at-35 ℃.

In addition to the features of the BP/BI, internal alkyl branches per molecule, 5+ methyl branches per molecule, and the Noack/CCS relationship described above, a hydrocarbon mixture according to the present invention having a number of carbon atoms in the range of C28 to C40, and in another embodiment a number of carbon atoms in the range of C28 to C36, or in another embodiment a number of carbon atoms in the range of C32, will typically exhibit the following characteristics:

KV100 in the range of 3.0-6.0 cSt;

VI in the range of 11ln (BP/BI) +135 to 11ln (BP/BI) + 145; and

pour points in the range 33ln (BP/BI) -45 to 33ln (BP/BI) -35.

In one embodiment, the C28-C40 hydrocarbon mixture has a KV100 in the range of 3.2 to 5.5cSt; in another embodiment, KV100 ranges from 4.0 to 5.2cSt; and in another embodiment from 4.1 to 4.5cSt.

The VI of the C28-C40 hydrocarbon mixture is in one embodiment from 125 to 155, and in another embodiment from 135 to 145.

The pour point of the hydrocarbon mixture is in one embodiment from 25 to-55 deg.C, and in another embodiment from 35 to-45 deg.C.

The boiling point range of a C28-C40 hydrocarbon mixture, as measured according to ASTM D2887, is in one embodiment no greater than 125 ℃ (TBP at 95% to TBP at 5%); in another embodiment no greater than 100 ℃; in one embodiment no greater than 75 ℃; in another embodiment no greater than 50 ℃; and in one embodiment no greater than 30 deg.c. In preferred embodiments, the Noack volatility (ASTM D5800) of those having boiling point ranges of no greater than 50 ℃, even more preferably no greater than 30 ℃, for a given KV100 is surprisingly low.

In one embodiment, the C28-C40 hydrocarbon mixture has a Branching Proximity (BP) in a range of from 14 to 30 and a Branching Index (BI) in a range of from 15 to 25; and in another embodiment, has a BP in the range of 15 to 28 and a BI in the range of 16 to 24.

The Noack volatility (ASTM D5800) of the C28-C40 hydrocarbon mixture is in one embodiment less than 16wt%; in one embodiment less than 12wt%; in one embodiment less than 10wt%; in one embodiment less than 8wt% and in one embodiment less than 7wt%. The C28-C40 hydrocarbon mixture also has a CCS viscosity at-35 ℃ as follows: less than 2700cP in one embodiment; less than 2000cP in another embodiment; less than 1700cP in one embodiment; and in one embodiment less than 1500cP.

In addition to the above-described features of BP/BI, internal alkyl branches per molecule, 5+ methyl branches per molecule, and Noack relationship to CCS at-35 ℃, hydrocarbon mixtures of C42 and larger carbon number ranges typically exhibit the following features:

KV100 in the range of 6.0-10.0 cSt;

VI in the range of 11ln (BP/BI) +145 to 11ln (BP/BI) + 160; and

pour points in the range 33ln (BP/BI) -40 to 33ln (BP/BI) -25.

Hydrocarbon mixtures containing C42 carbons or more have KV100 in one embodiment in a range from 8.0 to 10.0cSt, and in another embodiment from 8.5 to 9.5cSt.

The VI of the hydrocarbon mixture having 42 carbons or more is in one embodiment 140 to 170; and in another embodiment from 150 to 160.

Pour points range from-15 to-50 ℃ in one embodiment; and in another embodiment from-20 to-40 deg.c.

In one embodiment, the hydrocarbon mixture containing ≧ 42 carbons has a BP in the range of 18-28 and a BI in the range of 17-23. In another embodiment, the hydrocarbon mixture has a BP in the range of from 18 to 28 and a BI in the range of from 17 to 23.

In general, both hydrocarbon mixtures disclosed above exhibit the following characteristics:

according to FIMS, at least 80% of the molecules have an even number of carbons;

KV100 in the range of 3.0-10.0 cSt;

pour point range of-20 to-55 ℃;

so that Noack is at 2750 (-CCS at 35 ℃ C.) ^(-0.8) Relation between Noack between +/-2 and CCS at-35 ℃;

BP/BI in the range of ≧ 0.6037 (internal alkyl branching) +2.0 per molecule; and

an average of 0.3 to 1.5 5+ methyl branches per molecule.

High performance grease: a grease capable of working at high and low temperatures, under heavy loads, mechanically and shear stable, rust and corrosion resistant and stable under the influence of water and humid atmospheres, suitable for high and low speeds. For ease of understanding, the high performance characteristics of the greases are shown in Table 1

	ASTM test method	Multipurpose	High performance
				stability/Life time
Rolling stability, 2 hours; is based on	D 1831	≥10	＜10
				High temperature life at 160 deg.f; hour(s)	D 3527	＜80	＞80
Operating temperature and oxidative stability
				Oxidation resistance	D 942	≥10	＜10
Working temperature range, ° F	-	0 to 250F	0 to 350
				Load/wear protection
Welding load, kg	D 2596	＜250	＞250
				Diameter of grinding mark mm	D 2266	≥0.6	≤0.6
Fretting wear, mg	D 4170	-	＜10
				Coefficient of friction	D 5707	≥0.1	＜0.1
Water resistance
				Water rinse, 79C; is based on	D 1264	≥5	＜5
Rust and corrosion prevention	D 1743	Qualified	Qualified

* For reference only

The consistency of the grease composition has been tested according to ASTM D217, "standard test method for grease penetration". Penetration provides a measure of grease consistency/hardness under specified test conditions. The stability of the grease composition has been evaluated by testing the rolling stability of the grease, as tested by ASTM D1831-19, "standard test method for rolling stability of greases". This test method provides a change in consistency of the grease under rolling shear (as measured by cone penetration) while operating in a rolling stability test apparatus. The smaller the change in the cone penetration difference before and after the test, the better the stability of the grease under rolling shear. The high temperature life of the grease composition has been tested by ASTM D3527-18, "Standard test method for Life Performance of automotive wheel bearing greases". The test grease was distributed in the bearings of the automotive front hub-spindle-bearing assembly. The thrust load of the bearing is about 111N, the hub rotates at 1000r/min, the temperature of the main shaft is kept at 160 ℃ for 20 hours, and the working cycle is stopped for 4 hours. The test is terminated when grease degradation causes the drive motor torque to exceed the calculated motor cutoff. Grease life is expressed as cumulative cycle hours. The higher the test time, the longer the high temperature life of the grease. The high temperature life requirement of the NLGI GC-LB specification specified in ASTM D4950, "standard classification and specification for automotive service greases" is met for at least 80 hours. The high temperature life of ball bearings has been further evaluated according to ASTM D3336-18, "Standard test method for ball bearing grease Life at high temperatures". Grease lubricated SAE No.204 size ball bearings rotate at 10 000r/min under a thrust load of 22N 6 n (5lbf 6.55lbf) applied to the outer race of the bearing by a coil spring and at a temperature of 177 ℃. The test continues until failure or run time for a specified number of hours is completed. The longer the bearing fails, the longer the life of the grease under the test conditions.

The thermal stability and the oxidative stability of the grease compositions described in the present invention were tested according to ASTM D942-15, "standard test method for oxidative stability of greases by the oxygen pressure vessel method". The grease samples were oxidized in a pressure vessel heated to 99 ℃ (210 ° f) and filled with oxygen at 110psi (758 kPa). The pressure was observed and recorded at regular time intervals. The degree of oxidation after 100 hours was determined by the corresponding decrease in oxygen pressure and recorded as a psi drop. The oxidation stability of the grease samples was also measured by differential pressure scanning calorimetry (PDSC) according to ASTM D5483, "oxidation induction time of grease according to differential pressure scanning calorimetry". A small amount of grease was weighed into a sample pan and placed into the test cell. The cell was heated to the specified temperature (155 ℃, 180 ℃ and 210 ℃) and then pressurized with oxygen. The cell is maintained at the adjusted temperature and pressure until an exothermic reaction occurs. The extrapolated start time was measured and reported as the oxidation induction time of the grease at the specified test temperature. The oxidation induction time determined under the conditions of this test method can be used as an indicator of oxidative stability. The longer the oxidation induction time, the better the oxidation stability of the grease under the test conditions.

The anti-friction, load-bearing and wear protection properties of grease compositions have been evaluated according to ASTM D2596-15, "standard test method for measuring extreme pressure properties of greases (four ball method)" and ASTM D2266-01 (re-approved in 2015), "standard test method for grease wear resistance characteristics (four ball method)", three 1/2 inch (12.7 mm) diameter steel balls clamped together and covered with the lubricant to be evaluated. A fourth 1/2 inch diameter steel ball, referred to as the top ball, was pressed into the cavity formed by the three clamped balls with a force of 40kgf (392N) to achieve three point contact. The temperature of the grease sample was adjusted to 75 ℃ (167 ° f) and then the top ball was rotated at 1200rpm for 60 minutes. Lubricants were compared by using the average size of the worn scar diameters on the three lower clamping balls. This method was further extended to evaluate the coefficient of friction under these particular conditions.

The overbased calcium sulfonates may have a Total Base Number (TBN) of from 300 to 450mgKOH/g in mineral, white or synthetic hydrocarbon diluents.

To facilitate the conversion process, promoters may be used which convert amorphous calcium carbonate to calcite, such as propylene glycol, C1-3 alcohols, C1-5 monocarboxylic acids, water, methyl cellosolve itself or combinations thereof.

To facilitate the complexing process of one or more inorganic acids containing boron or phosphorus, such as boric acid and phosphoric acid, organic acids may be used, containing aromatic acids such as salicylic acid, monocarboxylic acids such as acetic acid, dicarboxylic acids such as azelaic acid and long chain fatty acids containing at least C12 carbon atoms, such as 12-hydroxystearic acid.

In order to fully illustrate the essence of the present invention, specific embodiments will be described below. It is to be understood, however, that this is done by way of example only and is intended to illustrate and not limit the scope of the appended claims.

Examples

Example 1.

In this example, a novel composition of overbased calcium sulfonate complex (OBCSC) grease using renewable base oils is disclosed for the first time, as shown in table 2.

TABLE-2

Components	By weight%
		SynNova 9	55.05
Overbased calcium sulfonates (Lubrizol GR 9251)	38.05
		Water (W)	11.00
Calcium hydroxide	2.21
		Boric acid	2.04
12-Hydroxystearic acid	2.65

120 g of base oil are charged into a kitchen auxiliary mixer and 430 g of Newtonian overbased calcium sulfonate (LZ GR 9251) are added thereto with continuous stirring. To this mixture 60 g of water was added and mixing continued for 45-60 minutes. Heat was continuously and slowly supplied to the mixer and the temperature was raised to 180-190 ℃ F. To this mixture was added 120 grams of oil. In a separate tank, a slurry of 20.40 grams boric acid, 22.10 grams calcium hydroxide, and 50 grams water was prepared and then added to this mixture. To this mixture was added 120 grams of oil. The material was heated to 200-220 ° f and then 26.50 grams of 12-hydroxystearic acid was added. The temperature is gradually increased to 300-320 ℉. Subsequently, the heating was turned off and the mass was gradually cooled, the balance base oil was added and ground by a 3-roll mill. The disclosed compositions do not contain any performance additives. The grease obtained exhibited the following characteristics as shown in table-3.

TABLE-3

According to table-3, the test data shows that the greases disclosed in this embodiment exhibit excellent stability without any performance additives, as indicated by a change in rolling stability of only 1.29%; an extremely high drop point of +600 ° f; 295kg welding load, thus having high bearing capacity; excellent antiwear properties, as indicated by a low wear scar diameter of only 0.324mm and fretting wear of only 0.6 mg; excellent anti-friction characteristics, as indicated by a low coefficient of friction of 0.084; excellent high temperature life of 85.7 hours at 160 ℃ (ASTM D3527) and 64.4 hours at 177 ℃ (ASTM D3336); excellent oxidative stability, as indicated by a psi drop of only 1.1 after 100 hours (ASTM D942) and an oxidative induction time of 19.9 minutes at 180 ℃ (ASTM D5483); and thus is likely to become a high-performance grease for wide use.

This grease may alternatively be prepared in a similar or other alternative process using other newtonian overbased sulfonate sulfonates known to those of skill in the art supplied by Lubrizol (LZ 75NS, LZ 75GR, LZ 75WR, LZ 75P), lockard, oronite, chemtura, daubert chemicals.

Example 2:

in this example, a grease composition was prepared using almost the same composition and method as described in example 1, but the base oil used to prepare the grease was a synthetic polyalphaolefin (PAO-8) oil with a viscosity of 8cSt at 100 ℃ instead of SynNova 9. The resulting grease properties have been compared to greases prepared according to example 1 using SynNova9, and the test results are listed in table-4.

TABLE-4

Table-4 clearly shows that the OBCSC grease prepared in renewable SynNova9 exhibited less thickener content than the same grease prepared in PAO-8 with the same composition and method. Less thickener content indicates better dispersability/solubility of the overbased calcium sulfonate thickener in the base oil. The solubility/dispersability of the thickener in the base oil plays an important role in guiding the performance characteristics of the grease, such as consistency, mechanical/shear stability and bearing noise, as can be seen from: the rolling stability was better in the case of the grease based on SynNova9 oil, 1.29%, compared to 1.64% in the case of the grease prepared with PAO8 and tested according to ASTM D1831, and as such passed

The bearing noise tested was relatively low for the SynNova9 based grease, 4.9, and 5.6 for the PAO8 based grease.

As indicated in table-4, the OBCSC grease prepared in SynNova9 exhibited higher load bearing capacity as indicated by a higher weld load of 295kg compared to 275kg of OBCSC grease prepared with PAO-8 base oil.

The anti-wear properties of the OBCSC grease prepared with SynNova9 showed a much superior wear scar of 0.324mm compared to 0.422mm for the corresponding OBCSC grease prepared in PAO-8 tested according to ASTM D2266. The OBCSC grease prepared with SynNova9 in example 1 had similar anti-wear performance characteristics, exhibiting only 0.6mg fretting, compared to 4.4mg OBCSC grease prepared in PAO-8; testing was performed according to ASTM D4170.

The high temperature life of the OBCSC grease prepared with SynNova9 in example 1 was 85.7 hours as tested according to ASTM D3527 at 160 ℃, compared to only 40.4 hours for the same OBCSC grease prepared with PAO-8. This observation is further supported by the fact that: the life of the OBCSC grease prepared with SynNova9 base oil was 64.4 hours as tested in ball bearings at 177 deg.C (ASTM D3336), compared to 53 hours for the same OBCSC grease prepared with PAO-8 in this example.

The antioxidant properties of the two greases prepared in examples 1 and 2 were compared according to ASTM D942 and ASTM D5483. The OBCSC grease prepared with SynNova9 base oil in example 1 exhibited a pressure drop of only 1.1psi after 100 hours at 100 ℃, compared to 1.6psi for the OBCSC grease prepared in PAO-8, thus the lower pressure drop for the grease prepared with SynNova9 oil indicates superior oxidation resistance. This observation is further supported by PDSC testing grease at 180 ℃ (ASTM D5483) where the OBCSC grease prepared with SynNova9 exhibited a longer induction time of 19.9 minutes compared to 16.6 minutes for the OBCSC grease prepared in PAO-8.

Example 3

In this example, a grease composition was prepared identically to that described in example 1, but the base oil used for the preparation was a mineral oil; 600N instead of SynNova 9. The properties of the resulting grease are compared in table 5-with the grease prepared with SynNova9 as described in example 1.

TABLE-5

Table-5 clearly shows that the OBCSC grease prepared in renewable SynNova9 exhibited a lower thickener content of 44.95% compared to 46.8% for the same grease prepared in the same composition and process in 600N base oil. The Anderometer test had a bearing noise of 4.9, which was better for the grease made in SynNova9 oil, compared to 7.7 for the grease made in 600N oil. The water rinse characteristics of greases tested according to ASTM D1264 and prepared with SynNova9 base oil exhibited 1.75% water rinse compared to 2.0% for the same grease prepared in 600N base oil. The lower the water flush, the better the water resistance characteristics of the grease.

The anti-wear properties of the OBCSC grease prepared with SynNova9 showed a much superior wear scar diameter of 0.324mm compared to 0.413 for the corresponding OBCSC grease prepared in 600N tested according to ASTM D2266. The OBCSC grease prepared with SynNova9 in example 1 had similar anti-wear performance characteristics, giving only 0.6mg fretting wear compared to 4.4mg prepared in 600N; testing was performed according to ASTM D4170.

The high temperature life of the OBCSC grease prepared with SynNova9 in example 1 was 85.7 hours, as tested at 160 ℃ according to ASTM D3527, compared to only 40.0 hours for the same OBCSC grease prepared with 600N.

The antioxidant properties of the two greases prepared in example 1 and example 3 were compared according to ASTM D942. The OBCSC grease prepared with SynNova9 base oil in example 1 exhibited a pressure drop of only 1.1psi after 100 hours at 100 c, compared to 3.2 for the same prepared OBCSC grease with 600N according to example 3, thus the lower pressure drop of the grease prepared with SynNova9 oil indicates superior oxidation resistance.

Example 4

In this example, lithium 12 hydroxystearate grease was prepared by a conventional open-pan process taking 158.6 grams of SynNova9 in a single-rotation medium speed kitchen mixer. To this mixer 126.8 grams of 12 hydroxystearic acid was added and heated to melt. To this mixture was added 19.0 grams of aqueous lithium hydroxide monohydrate slurry and then 200 grams of SynNova9 oil. The temperature was gradually increased to 400 ° f with continuous stirring. At this temperature, the heat was turned off and 495.6 grams of SynNova9 was further added. The mass was cooled to <180 ° f and ground by a 3-roll mill and tested as indicated in table-6. For comparison purposes, other lithium-based greases also used the same raw materials and the same method using a group II mineral oil; chevron 600R and synthetic polyalphaolefin 8cSt base oils. Comparative test data are listed in table 6 below.

TABLE-6

Table-6 shows that lithium-based greases prepared in renewable SynNova9 exhibited a lower thickener content of 14.58% compared to 16.08% for the same grease prepared in the same composition and method in PAO8 base oil and 16.13% thickener content in 600R oil. The shell roll stability of greases prepared with renewable SynNova9 oil was 1.72% better than greases prepared with PAO8 and 600R (2.69% and 2.76%, respectively). The grease prepared with SynNova9 had an average bearing noise of 7.7, which is better than the greases prepared with PAO8 and 600R, with average noise of 8.2 and 8.5, respectively. The water wash characteristics of the lithium-based grease prepared with SynNova9 base oil exhibited a better water wash of 2.00% compared to 2.5% for the grease prepared in PAO8 and 4.5% for the grease prepared in 600R.

The anti-wear properties of the lithium grease prepared with SynNova9 showed a wear scar diameter of 0.552mm, which is much superior compared to 0.631mm for the corresponding lithium grease prepared in PAO8 and 0.585mm for the grease prepared in 600R. This test result was further verified by running the same test on different equipment but with a friction curve. The grease prepared with SynNova9 exhibited a wear scar diameter of 0.75mm compared to 1.01mm for the grease prepared with PAO 8. The average coefficient of friction of the lithium grease prepared with SynNova9 base oil was 0.088 and the Y-O intercept was 0.088, however the values were found to be much higher in the case of the lithium grease prepared with PAO8, with an average coefficient of friction of 0.115 and a Y-O intercept of 0.093, as shown in fig. 1 and 2. Fig. 1 corresponds to a lithium-based grease prepared with SynNova9, clearly highlighting a uniform and smooth friction pattern during testing compared to the irregular friction pattern with a fractured film in fig. 2 (indicating potential metal-to-metal contact).

The high temperature life of the lithium grease prepared in SynNova9 tested in ball bearings at 177 ℃ according to ASTM D3336 was 73.2 hours, compared to the shorter life of the same lithium grease prepared with PAO-8 in this example, which was only 60 hours.

The antioxidant properties of the two greases prepared in this example without any additives were compared according to ASTM D942 and ASTM D5483. Lithium-based greases prepared with SynNova9 base oil exhibited a pressure drop of 72.5psi after 100 hours at 100 c, compared to 95.4 for lithium-based greases prepared and tested in the same manner with PAO-8 and 99.3 for greases prepared in 600R oil. This observation was further confirmed by testing of the same grease by PDSC at 155 ℃ (ASTM D5483), where the lithium-based grease made with SynNova9 exhibited a higher induction time of 21.4 minutes, compared to <10 minutes in the case of the lithium-based grease made with PAO-8.

Example 5

In this example, the effect of the well-known anti-wear additive zinc dialkyldithiophosphate (ZDDP) on the comparative wear scar diameters for all of the greases prepared in examples 1, 2 and 3 is presented. All three greases were treated with 1% LZ 1395 (a commercial zinc dialkyldithiophosphate (ZDDP) supplied by Lubrizol corporation having a typical phosphorus content of 9.50%, a sulfuric acid ash content of 15.90%, and a zinc content of 10.60%). The results of the tests with and without ZDDP are listed in Table-7.

TABLE-7

The OBCSC grease prepared in SynNova base oil according to example 1 showed a wear scar of 0.324mm, whereas the same OBCSC grease prepared with PAO8 according to example 2 showed a wear scar diameter of 0.422. The wear scar diameter was reduced to 0.32mm when 1% ZDDP as described above was incorporated into the same grease, almost the same as the wear scar diameter of the OBCSC made with SynNova9 without any additives (including ZDDP). Similarly, an OBCSC grease prepared according to example 3 in a group I mineral oil 600N oil exhibited a wear scar diameter of 0.413mm without any antiwear additive. When the same grease was blended with 1% of the above ZDDP, the wear scar diameter decreased from 0.413mm to 0.388mm. If we compare the wear scar diameters of OBCSCs made with SynNova9 without any ZDDP/antiwear additive, they show a 0.324mm wear scar diameter, which is lower than the wear scar diameter (0.388) of the same OBCSC made with 600N oil even with 1% ZDDP; higher than the obscc grease prepared in SynNova9 oil and without any ZDDP.

Example 6

Watch-8

In this example, the effect of antioxidant additives on OBCSC and lithium-based greases prepared in SynNova9, PAO8, and 600R were compared. The grease was spiked with 0.5% or 1.0% LZ9510, a substituted diarylamine type oxidation inhibitor with a typical nitrogen content of 3.5%, and tested for oxidation induction time by PDSC at various temperatures according to ASTM D5483. In the 1% LZ9510 containing OBCSC grease prepared in SynNova9, the oxidation induction time was >120 minutes, no isotherm at 210 ℃, compared to 58.3 minutes in the case of the 1% LZ9510 containing OBCSC grease prepared in 600R and 123.2 minutes in the case of the grease prepared with PAO 8. To obtain a clear distinction, the tests were run with all three greases containing 0.5% LZ 9510. The induction time at 210 ℃ for OBCSC prepared in SynNova9 containing 0.5% LZ9510 was 84.5 minutes, compared to 60.45 and 23.4 minutes in the case of OBCSC greases prepared with PAO8 and 600R, respectively. This test was run at 180 ℃ for lithium-based greases prepared with SynNova9 and PAO8, and the test result for the lithium-based grease prepared in SynNova9 with 1.0% LZ9510 was >120 minutes, and the test result for the grease prepared in PAO8 with 1% LZ9510 was 98.4 minutes. This example clearly shows that with the addition of known antioxidants to these greases, the greases made in SynNova9 retain their performance characteristics superior to other greases made in PAO8 or mineral oil base 600R.

Claims

1. A high performance non-newtonian overbased calcium sulfonate complex grease composition comprising an overbased calcium sulfonate and a renewable base oil.

2. The composition of claim 1, wherein the renewable base oil comprises KV100 in the range of 3.0 to 10.0 cSt; -a pour point in the range of-20 to-55 ℃; such that Noack has a relationship between Noack at 2750 (-CCS at-35) (-0.8) ± 2 to CCS at-35 ℃.

3. The composition of claim 2, wherein the renewable base oil comprises the following NMR parameters: (a) The BP/BI of the hydrocarbon mixture is in the range of ≧ 0.6037 (internal alkyl branching per molecule) +2.0, and (b) the 5+ methyl of the hydrocarbon mixture averages 0.3 to 1.5 per molecule.

4. An antiwear composition comprising the composition of claim 3, wherein no additional performance additives are required.

5. The composition of claim 4, wherein the composition is zinc-free.

6. A method of forming a non-newtonian oil composition in the form of a grease comprising an overbased calcium sulfonate and a renewable base oil, (1) heating the overbased calcium sulfonate, calcium hydroxide, and a conversion agent, comprising a renewable base oil having: KV100 in the range of 3.0-10.0 cSt; -a pour point in the range of from 20 to-55 ℃; the relationship of Noack to CCS at-35 ℃ such that Noack is between 2750 (-CCS at-35 ℃) (-0.8) ± 2; (2) Reacting the product of step 1 with a component comprising a boronic acid compound to produce a grease-like characteristic.

7. The process of claim 6, wherein the reaction is carried out in the presence of 12-hydroxystearic acid.

8. A grease composition comprising a renewable base oil and a thickener, wherein the renewable base oil comprises KV100 in the range of 3.0 to 10.0 cSt; -a pour point in the range of-20 to-55 ℃; the relationship of Noack to CCS at-35 ℃ such that Noack is between 2750 (-CCS at-35 ℃) (-0.8) ± 2; and the thickener is selected from the group consisting of: lithium, aluminum composites, clay-based, and polyurea.

9. The composition of claim 8, wherein the renewable base oil comprises the following NMR parameters: (a) The BP/BI of the hydrocarbon mixture is in the range of ≧ 0.6037 (internal alkyl branching per molecule) +2.0, and (b) the 5+ methyl of the hydrocarbon mixture averages 0.3 to 1.5 per molecule.

10. The composition of claim 9, wherein the composition is free of additional performance additives.

11. The composition of claim 9, wherein the composition comprises additional performance additives.