DESC:FIELD OF THE INVENTION

The present invention generally relates to the field of lubricant compositions and manufacturing processes, and more specifically to a biodegradable grease composition and a method of preparation thereof.

BACKGROUND OF THE INVENTION

The increasing environmental concerns associated with the widespread use of mineral Oil based lubricants, particularly greases, have highlighted the urgent need for more sustainable and less harmful alternatives. Traditional greases, primarily based on mineral oils derived from petroleum, pose significant environmental risks. Their non-biodegradable nature leads to accumulation in ecosystems, causing soil and water contamination that adversely affects flora, fauna, including human, wild, and marine life. Furthermore, the production of these petroleum-based lubricants is energy-intensive, contributing to greenhouse gas emissions and exacerbating the carbon footprint of industrial operations.
In response to these environmental challenges, various alternatives have been developed, focusing on either synthetic or bio-based lubricants. Synthetic lubricants, designed to offer similar or superior performance to their mineral oil counterparts, often emphasize reduced toxicity and enhanced biodegradability. Meanwhile, bio-based lubricants, derived from renewable resources such as vegetable oils, have been promoted as environmentally friendly options due to their ready biodegradability and lower toxicity. These solutions represent a shift towards more sustainable practices in lubricant manufacturing and application.
However, despite these advancements, existing solutions often fall short of fully addressing the environmental and performance needs of modern applications. Synthetic lubricants, while less toxic, may still present biodegradability challenges and environmental concerns. Bio-based lubricants, on the other hand, can suffer from oxidative instability, limited temperature ranges, and performance under high stress conditions, making them less suitable for certain industrial applications. Furthermore, the production of both synthetic and bio-based alternatives can involve complex processes that may offset some of their environmental benefits.
Given the shortcomings of existing mineral oil-based lubricant solutions, there is a clear and pressing need for a new approach that not only mitigates the environmental impact but also meets the performance demands of diverse applications. This need underscores the importance of developing a biodegradable grease composition and a method of preparation thereof, which aims to overcome the limitations of current technologies by offering an environmentally friendly, high-performance alternative suitable for broad application. Such an invention would represent a significant advancement in the field of lubricants, providing a viable solution to the environmental and operational challenges posed by traditional lubricants.

OBJECT OF THE INVENTION
An object of the present invention is to create a grease composition that is environmentally friendly, utilizing materials that are biodegradable and derived from renewable resources, thereby reducing the environmental impact associated with traditional petroleum-based lubricants.
Another object of the present invention is to offer a grease composition that not only exhibits high biodegradability but also maintains or exceeds the performance characteristics of traditional greases, including stability, lubricity, and temperature resistance.
Yet another object of the present invention is to develop a grease composition that demonstrates enhanced durability and longevity, reducing the need for frequent reapplication and thereby lowering the total lifecycle environmental impact of the lubricant.
Yet another object of the present invention is to provide a grease composition that is non-toxic to both flora and fauna, ensuring that accidental spills or leaks have minimal adverse effects on the environment.
Yet another object of the present invention is to offer an efficient method for preparing the biodegradable grease composition, utilizing processes that are less energy-intensive and produce fewer byproducts, further enhancing the environmental benefits of the invention.
Yet another object of the present invention is to provide a versatile grease composition that is suitable for a wide range of applications, from industrial machinery to automotive uses including agriculture, water ways and marine, without compromising on environmental sustainability or performance.

SUMMARY OF THE INVENTION

According to an aspect of the present invention, a biodegradable grease composition for industrial, marine, and agricultural applications comprises 70-90% by weight of a synthetic ester base fluid derived from renewable resources, 5-15% by weight of a lithium complex soap thickener formed in situ by reacting lithium hydroxide monohydrate with 12-Hydroxy Stearic acid and dicarboxylic acids (C6-C18), and 0.1-10% by weight of performance enhancement additives selected from antioxidants, anti-wear agents, and metal deactivators, ensuring enhanced lubricating properties and biodegradability.
In accordance with an embodiment of the present invention, the synthetic ester base fluid is a saturated polyol ester with up to 97% renewable content, contributing to its environmentally friendly nature.
In accordance with another embodiment, the ratio of 12-Hydroxy Stearic acid to dicarboxylic acids ranges from 5:1 to 2:1, optimizing the grease's consistency and structural stability.
In accordance with another embodiment, the dicarboxylic acids used in the thickener formation are selected from adipic acid, sebacic acid, azelaic acid, and branched-chain dicarboxylic acids, ensuring compatibility with high-performance lubrication requirements.
In accordance with another embodiment, the biodegradable grease composition exhibits a dropping point exceeding 260°C and up to 316°C, providing superior thermal stability and mechanical durability comparable to or exceeding mineral oil-based lithium complex greases.
According to another aspect of the present invention, a method (100) for preparing a biodegradable grease composition comprises heating (102) a synthetic ester base fluid to 60-80°C, adding (104) lithium hydroxide monohydrate, introducing (106) 12-Hydroxy Stearic acid and dicarboxylic acids under continuous stirring, heating (108) the mixture to 180-220°C to facilitate the in-situ formation of a lithium complex soap thickener, cooling (110) the mixture to ambient temperature, and adding (112) 0.1-10% by weight of performance enhancement additives under controlled conditions to achieve homogeneity.
In accordance with an embodiment of the present invention, the base fluid is a saturated polyol ester with up to 97% renewable content, ensuring biodegradability and sustainability.
In accordance with another embodiment, the ratio of 12-Hydroxy Stearic acid to dicarboxylic acids ranges from 5:1 to 2:1, allowing control over the grease's consistency and performance characteristics.
In accordance with another embodiment, the method incorporates advanced processing techniques, such as ultrasonic mixing or microwave-assisted synthesis, to improve reaction efficiency and enhance the dispersion of additives.
In accordance with another embodiment, the biodegradable grease composition is prepared to achieve varying NLGI consistencies, making it suitable for industrial machinery, automotive lubrication, agriculture, waterways, and marine environments, ensuring optimal performance across diverse applications.

BRIEF DESCRIPTION OF THE DRAWINGS
So that the manner in which the above recited features of the present invention can be understood in detail, a more particular to the description of the invention, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, the invention may admit to other equally effective embodiments. These and other features, benefits and advantages of the present invention will become apparent by reference to the following text figure, with like reference numbers referring to like structures across the views, wherein:
Fig. 1 illustrates a method (100) for preparing a biodegradable grease composition, in accordance with the present invention.
DETAILED DESCRIPTION OF THE DRAWINGS
The present invention is described hereinafter by various embodiments. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiment set forth herein. Rather, the embodiment is provided so that this disclosure will be thorough and complete and will fully convey the scope of the invention to those skilled in art.
This invention relates to a novel biodegradable grease composition and a method for its preparation, designed to provide an environmentally sustainable alternative to traditional petroleum-based lubricants. The invention encompasses both the formulation of the grease composition in broad terms and ranges, and the detailed process for its preparation, ensuring coherence, consistency, and comprehensive coverage of all aspects.
The biodegradable grease composition of the present invention primarily comprises a synthetic ester base fluid, lithium soap as a thickener, and a suite of performance enhancement additives. The synthetic ester base fluid, derived from renewable resources accounts for approximately 70-90% by weight of the total composition, and having ready biodegradability of more than 60% as per OECD 301B as claimed by the supplier of the Synthetic Ester. This base fluid is selected for its excellent biodegradability, low toxicity, and high renewable content, which can reach up to, but not limited to, 97%.
In accordance with an embodiment of the present invention, alternative base fluids may be explored beyond synthetic ester to include polyalphaolefin (PAO) or biodegradable polyalkylene glycol (PAG) at certain percentages, aiming to further enhance the environmental profile and performance under extreme conditions. These alternative base fluids could be used solely or in combination with synthetic esters to achieve desired properties such as improved low-temperature performance or enhanced shear stability. The composition may vary, with the alternative base fluids constituting anywhere from 60-90% by weight of the total composition, adjusted based on the specific application requirements and environmental goals.
The thickening agent, a lithium complex soap, is formed in-situ and constitutes about 5-15% by weight of the composition. It is produced through the reaction of lithium hydroxide monohydrate with 12-Hydroxy Stearic acid and dicarboxylic acids, which have carbon chain lengths ranging from C6 to C18, including, but not limited to, adipic acid, sebacic acid, and azelaic acid. The ratio of 12-Hydroxy Stearic acid to dicarboxylic acids varies from 5:1 to 2:1, allowing for adjustments in the grease's consistency and performance characteristics.
In accordance with another embodiment of the present invention, the thickening agent may be varied to include calcium soap, aluminum soap, or other biodegradable soap thickeners in addition to, or instead of, lithium soap. This variation aims to tailor the grease's properties for specific applications, such as water resistance or higher dropping points. The choice of thickener impacts the grease's consistency and performance, with the ratio of the thickening agent to the base fluid adjusted to achieve the desired NLGI grade, ranging from very soft to very hard greases, thereby expanding the invention's applicability across different industrial and automotive uses.
Performance enhancement additives are included in the composition to improve properties such as load-bearing capabilities, anti-wear performance, and oxidation stability. These additives, which are derived from renewable sources whenever possible, make up about 0.1-10% by weight of the total composition. Examples of such additives include, but are not limited to, ashless antioxidants, ashless anti-wear agents, and metal deactivators. These components are carefully selected to ensure compatibility with the synthetic ester base fluid and to maintain the overall biodegradability of the grease.
In accordance with a further embodiment of the present invention, the range and type of performance enhancement additives can be broadened to include innovative, environmentally friendly additives such as graphene nanoparticles for improved thermal conductivity and wear resistance, or natural plant extracts with antioxidative properties. The inclusion of such additives, in concentrations ranging from 0.5-10% by weight, is designed to not only enhance the performance characteristics of the grease but also to bolster its environmental sustainability and biodegradability. This approach allows for the customization of the grease to meet specific performance criteria while adhering to stringent environmental standards.
In accordance with an embodiment of the present invention, in addition to the base composition, the grease is further enhanced with a selection of performance enhancement additives and chemicals. These additives, which are also commonly used in mineral oil greases, are meticulously chosen to improve properties such as load-bearing characteristics, antiwear properties, and oxidation stability. Through the strategic combination of these additive systems, the grease not only meets but, in some cases, exceeds the performance properties of conventional mineral oil-based lithium complex greases.
The incorporation of these additives does not compromise the grease's environmental profile. The finished greases are expected to exhibit good biodegradability, attributed to the inherent biodegradability of the synthetic ester base fluid. This combination of high-performance characteristics with environmental sustainability underscores the innovative nature of the grease composition, aligning it with current and future needs for more sustainable lubrication solutions.

Exemplary Method of preparation:
A method (100) of preparation for the biodegradable grease involves a series of controlled steps. Initially, the synthetic ester base fluid is heated (102) to a temperature range of 60-80°C. Lithium hydroxide monohydrate is then introduced (104) to the heated base fluid, followed by the gradual addition (106) of 12-Hydroxy Stearic acid and the selected dicarboxylic acids under continuous stirring and further heating (108) upto 180 – 220 deg. C. This ensures complete reaction and the formation of a homogeneous lithium soap thickener within the mixture.
After the thickening agent has been fully integrated, the mixture is allowed to cool (110) to room temperature. At this point, the performance enhancement additives are added (112) and mixed thoroughly to achieve a uniform final product. The entire process is designed to be energy-efficient, minimizing waste and aligning with the environmental objectives of the invention. This method enables the production of greases with varying NLGI consistencies, tailored to meet the specific requirements of a wide range of applications.
In accordance with yet another embodiment of the present invention, the method (100) of preparation may incorporate advanced techniques such as ultrasonic mixing or microwave-assisted synthesis to enhance the efficiency of the reaction process and improve the dispersion of additives within the grease composition. These techniques can lead to a more homogenous product, potentially reducing the energy consumption and processing time required for grease manufacturing. Such variations in the preparation method (100) highlight the invention's flexibility and adaptability to different manufacturing settings, emphasizing its potential for scalable production and widespread application.
The biodegradable grease compositions achieved through this invention exhibit exceptional performance characteristics, notably in terms of their thermal stability and mechanical robustness. Specifically, the greases obtained have a dropping point in excess of 260°C, with some formulations reaching up to 316°C. This high dropping point indicates superior thermal stability, making the grease suitable for applications where high temperatures are encountered.
Furthermore, the mechanical stability of these greases is very good, comparable to or even surpassing that of traditional mineral oil-based lithium complex greases. This ensures that the grease maintains its integrity and lubricating properties under mechanical stress, further enhancing its applicability across a wide range of industrial and automotive scenarios.
Each of these embodiments underscores the invention's versatility and adaptability, offering a range of alternatives and variations that can be tailored to meet specific performance requirements and environmental sustainability goals. This flexibility ensures that the invention remains relevant and applicable across a broad spectrum of lubrication challenges, further illustrating its innovative contributions to the field of environmentally friendly lubricants.
The following table 1 presents various bio grease formulations, detailing the composition of raw materials used in different experimental examples. It includes reference formulation alongside multiple variations, allowing for a structured comparison of ingredient proportions:

Table 1: Examples of Bio Greases
Table 1 presents a comparative analysis of various bio grease formulations, listing different raw materials and their respective quantities across multiple experimental examples. The table is structured with raw materials listed in the first column, followed by their corresponding quantities in twelve experimental examples. Key raw materials include Lithium (Lithium hydroxide mono hydrate), 12-Hydroxy Stearic Acid (12 HSA– mono basic acid), Dibasic acid (either Sebacic Acid, Dibasic acid (either Sebacic Acid,), among others. Lithium soap, a common thickener, is present in all formulations but varies slightly in concentration, ranging from 1.72% to around 3.8% in twelve Examples. 12 HSA, essential for grease structure, is used consistently across formulations but fluctuates between 9% and 12%. For making Lithium Complex bio greases, Mono basic acid and Dibasic acid were being used in between 5:1 to 2:1 ratio. These examples cover these ratios of two acids (12 HSA – mono basic acid is constant for all examples and second Dibasic acid is Sebacic / Azelaic / Adipic acid) for making lithium complex greases. One of the second acids - Sebacic / Azelaic / Adipic Acid - appears in formulations with first acid (12HSA) and their ratio were varies between 5:1 to 2:1 under controlled experimentation to analyze its effect on grease properties. A combination of two commercial Synthetic Esters “1” and “2” were used to achieve kinematic viscosity of synthetic base esters either ISO VG 150 or ISO VG 220. A combination of Antiwear, Antiwear Booster, Extreme Pressure (EP), Metal Deactivator, Anti Rust additive, and two antioxidant additives have been used in these greases consistently to achieve desired grease properties w.r.t. antiwear, EP, copper corrosion, rust test and oxidation test matching the application requirements. It is important to note that Drop point was found to be higher in higher dosages of Dibasic acid content in the grease formulations. The water washes out properties of these bio greases found very good. The experimental formulations (Examples 1–12) showcase variations in ingredient concentrations, likely to evaluate their impact on performance, stability, and environmental sustainability. The additive ingredients remain constant across formulations, while others are adjusted to test their influence on the final product. This structured comparison helps in identifying the most effective formulation for industrial applications, ensuring optimal lubrication performance and sustainability.
The commercial conventional Lithium Complex Grease with mineral oil (Reference Grease) is being used in the industry satisfactorily and provides very good life for the bearings. The properties of this commercially proven “Reference Grease” is being compared with the present invention Bio Grease – Example 1 in the following Table 2 having similar drop point (~266 0C) and NLGI consistency (~ 270 penetration in ASTM D217). The grease is being sheared in the bearing during actual application and these characteristics are being evaluated as per ASTM test methods mechanical stability by observing change in penetration after 100,000 strokes in ASTM D217 and change in penetration after rolling at Room Temperature (RT) for 16 hours under load & 165 rpm rotation in ASTM D1831. In order to study further stringent conditions, the mechanical stability and roll stability were also evaluated in the presence of 10% water and change in penetration were compared for Bio Grease and Reference Grease. The following table clearly indicates that “Bio Grease” is having superior mechanical stability (penetration change just 19 units in Bio Grease against 30 units change in reference grease after 100000 strokes) and roll stability (8.5% in bio grease and 15% in reference grease). The lower change in penetration suggests that grease will stay for longer period of time in the bearing and provide satisfactory lubrication for longer period of time. The grease structure of Bio Grease was found significantly superior as compared to reference grease in presence of 10% water as the change in penetration was lower (33 units against 45 units after 100000 strokes with 10% water and 13.3% against 18% in roll stability at RT for 16 hours with 10% water). The weld load and oil separation characteristic were also found superior in Bio grease in comparison to reference grease. This comparison of Bio Grease and industry proven commercial lithium complex reference grease clearly establishes that the new Bio Grease will provide superior lubrication in the field.
Table 2: Comparative Test Results of Bio Grease and Lithium
Complex Grease with conventional mineral oil (reference grease)
S.No. Properties Example 1 - Bio Grease Conventional Lithium Complex Grease - Mineral Oil (Reference Grease)
1 Appearance Beige Yellowish brown
2 Drop point, C 266 267
3 Worked penetration W60 271 273
4 Penetration after 100000 strokes 290 (+19) 303 (+30)
5 Oil separation, 48 hours , D 6184 1.8 2.4
6 Water wash out @ 79 C , % loss 4.5 4.4
7 Copper corrosion test 1b 1b
8 Four Ball WSD, mm 0.6 0.6
9 Four Ball WL, kgf 400 315
10 D1743 rust test Pass Pass
11 EMCOR Test , IP 220 , DW 0,0 0,0
12 Penetration with 10% water after 100000 strokes 304 (+33) 318 (+45)
13 Rolling stability - penetration after rolling @RT, 16 hours, % Caahange 294 (8.5%) 314 (15%)
14 Rolling stability - penetration after rolling @RT, 16 hours with 10% water, % Caahange 307 (13.3%) 325 (18%)
15 Biodegradability Test results as per OECD 301B test method, % bio-degradation 71 <30

The present invention offers several distinct advantages:
1. Environmentally Friendly & Biodegradable: The grease composition is formulated with synthetic ester base fluids derived from renewable resources, ensuring high biodegradability and reducing environmental pollution compared to conventional mineral oil-based greases.
2. Reduced Toxicity: The use of non-toxic, biodegradable ingredients minimizes harm to human health, wildlife, and aquatic ecosystems in case of spills or leaks.
3. Superior Thermal Stability: The grease exhibits a dropping point exceeding 260°C and up to 316°C, making it suitable for high-temperature applications without degradation.
4. Enhanced Mechanical and Roll Durability: The in-situ lithium complex soap thickener ensures excellent mechanical stability, wear resistance, and anti-corrosion properties, providing long-lasting lubrication in demanding conditions. Results clearly indicate that Bio Grease is having significantly superior Mechanical and Roll stabilities.
5. Versatile Applications: The composition is optimized for industrial, automotive, marine, agricultural, and waterways applications, making it a multi-purpose, high-performance lubricant.
6. Improved Lubrication Performance: The inclusion of anti-wear agents, antioxidants, and metal deactivators enhances load-bearing capacity, oxidation resistance, and overall efficiency, reducing friction and wear in mechanical systems.
7. Customizable NLGI Consistencies: The grease formulation can be tailored to different NLGI grades, allowing flexibility for various industrial and mechanical lubrication requirements.
8. Sustainable Manufacturing Process: The preparation method involves energy-efficient processing techniques such as ultrasonic mixing and microwave-assisted synthesis, reducing the carbon footprint and promoting sustainable industrial practices.
9. Compliance with Environmental Regulations: The invention aligns with OECD 301B biodegradability standards and meets regulatory requirements for eco-friendly lubricants, ensuring global acceptance and compliance.

Various modifications to these embodiments are apparent to those skilled in the art from the description and the accompanying drawings. The principles associated with the various embodiments described herein may be applied to other embodiments. Therefore, the description is not intended to be limited to the embodiments shown along with the accompanying drawings but is to be providing broadest scope consistent with the principles and the novel and inventive features disclosed or suggested herein. Accordingly, the invention is anticipated to hold on to all other such alternatives, modifications, and variations that fall within the scope of the present invention.
,CLAIMS:We Claim

1. A biodegradable grease composition for industrial, marine and agricultural applications, the composition comprising:

70-90% by weight of a synthetic ester base fluid derived from renewable resources;

5-15% by weight of a lithium complex soap thickener formed in situ by reacting lithium hydroxide monohydrate with 12-Hydroxy Stearic acid and dicarboxylic acids having carbon chain lengths of C6 to C18; and

0.1-10% by weight of performance enhancement additives selected from antioxidants, anti-wear agents, and metal deactivators.

2. The biodegradable grease composition as claimed in claim 1, wherein the synthetic ester base fluid is a saturated polyol ester having at least 60% biodegradability as per OECD 301B standards.

3. The biodegradable grease composition as claimed in claim 1, wherein ratio of the 12-Hydroxy Stearic acid to dicarboxylic acids ranges from 5:1 to 2:1.

4. The biodegradable grease composition as claimed in claim 1, wherein the dicarboxylic acids are selected from the group consisting of adipic acid, sebacic acid, azelaic acid, and branched-chain dicarboxylic acids.

5. The biodegradable grease composition as claimed in claim 1, wherein the composition exhibits a dropping point exceeding 260°C and up to 316°C and possesses high mechanical stability comparable to or exceeding mineral oil-based lithium complex greases.

6. A method (100) for preparing a biodegradable grease composition, comprising:

heating (102) a synthetic ester base fluid to a temperature range of 60-80°C;

adding (104) lithium hydroxide monohydrate to the heated base fluid;

adding (106) 12-Hydroxy Stearic acid and dicarboxylic acids gradually under continuous stirring;

heating (108) the mixture to a temperature range of 180-220°C to ensure the formation of an in-situ lithium complex soap thickener;

cooling (110) the mixture to ambient temperature;

adding (112) 0.1-10% by weight of performance enhancement additives under controlled conditions to achieve homogeneity.

7. The method (100) as claimed in claim 6, wherein the base fluid is a saturated polyol ester derived from renewable sources and having at least 97% renewable content.

8. The method (100) as claimed in claim 6, wherein the ratio of 12-Hydroxy Stearic acid to dicarboxylic acids ranges from 5:1 to 2:1, allowing for control over grease consistency and performance characteristics.

9. The method (100) as claimed in claim 6, further comprising the step of incorporating advanced processing techniques, selected from ultrasonic mixing or microwave-assisted synthesis, to enhance reaction efficiency and improve the dispersion of additives.

10. The method (100) as claimed in claim 6, wherein the biodegradable grease composition is prepared to achieve varying NLGI consistencies, suitable for applications including industrial machinery, automotive lubrication, agriculture, waterways, and marine environments.