Grease comprising spent bleaching earth

Abstract

Described is a grease comprising at least one base oil, at least one primary thickener and optionally one or more additives comprising a second thickener and a polymeric additive in a smaller amount than the primary thickener wherein the primary thickener is one or more spent bleaching earth, and wherein the polymeric additive is one or more of the spent bleaching earth and the secondary thickener is one or more of the spent bleaching earth. The present invention relates to a lubricating grease composition comprising a base oil and a lubricating grease, and present in an amount of up to 80% to 90% by weight relative to the weight of the total composition of the lubricating grease, and wherein the base oil is a petroliferous oil or an oil of biological origin, a renewable oil and / or a biodegradable oil or a combination thereof, preferably a Group I mineral base oil (GPI), said lubricating grease being a non-fusible lubricating grease and being classifiable according to the NLGI rating.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This patent application claims the priority of Italian Patent Application No. 102022000019848 filed on September 27, 2022, the entire disclosure of which is incorporated herein by reference. Technical Field

[0003] The present invention relates to a lubricating grease containing at least one or more spent bleaching earths as primary thickener and characterized in that it has a consistency belonging to at least one of the grades of the NLGI (National Lubricating Grease Institute) classification, for example an NLGI consistency of 0, 1, 2, 3 or even higher, with such a low tendency to lose weight as to ensure that said consistency is maintained during the service life (mechanically stable grease during service).

[0004] In particular, the present invention relates to a grease as defined above, which also has a high drop point, preferably >350°C, so that it is classified as an infusible grease, and has good cold properties to be able to be used at temperatures as low as -10°C, and its lubricating properties are similar to those of infusible bentonite greases commonly used for lubricating mechanical moving members under high load conditions and possibly high temperature conditions (for example above 200°C), for example for lubricating bearings, gears and mechanical parts operating at extremely high temperatures, such as those of processes in cement plants and the steel industry, or mechanical parts of agricultural machinery.

[0005] More particularly, the present invention relates to a grease as defined above, which grease has improved performance characteristics compared to bentonite greases, such as for example the substantial absence of weight gain due to water incorporation, while further exhibiting low water washout values, preferably below 18 wt.-%, more preferably below 13 wt.-%, even more preferably below 10 wt.-%, thereby reducing water penetration.

[0006] These latter properties make the grease of the invention particularly suitable for use as a non-melting grease in humid environments and / or in the presence of water, even at low temperatures. Background Art

[0007] The purpose of lubrication with grease or oil is to reduce friction and wear between moving surfaces.

[0008] Grease has lower pumpability than oil and, by its nature, does not perform a cooling function. However, this type of grease has considerable advantages and must be chosen in certain situations.

[0009] Generally speaking, greases are used in bearings with rotating elements, smooth bearings, gearboxes and open gears, where they effectively prevent wear and corrosion, as they do not easily come off the lubricated surfaces, and also act as a "sealant" to prevent the penetration of dust and water: since there is no grease suitable for all operating conditions, the choice of the most suitable type of grease must obviously be evaluated on a case-by-case basis.

[0010] Greases generally contain a base oil (lubricating fluid or "stock oil"), at least one primary thickener and other optional additives that may impart certain properties to the finished product: they are usually subdivided based on their different consistencies, for example according to the NLGI grades, which can range from NLGI grade 000 (very fluid grease) to NLGI grade 6 (solid grease).

[0011] The primary thickener in grease is used to form a network / crystalline structure in which the base oil is retained inside, like water in a sponge, and greases are also identified based on the type of thickener employed as well as based on the consistency because this network / crystalline structure affects the properties of the grease.

[0012] The thickeners most commonly used to date are metal soaps, such as, for example, lithium soaps, but other substances, such as silica, polyureas and clays (bentonites), are also conceivable.

[0013] Of particular interest are non-melting greases known for lubrication under extremely high temperature and / or high load conditions, since they have a very high dropping point to avoid dripping of the base oil at operating temperature.

[0014] Among the infusible greases, mention may be made of those containing bentonite, also known as bentonite greases: in which the base oil constitutes the main part of the grease formula (at least 50% by weight), the bentonite (which is a phyllosilicate Al2O3-4SiO2-4H2O consisting essentially of montmorillonite, calcium or sodium) reaching a maximum of 10 to 15% by weight of the total weight of the formula.

[0015] The bentonite present in bentonite grease is usually pretreated and modified so that the sodium (and / or calcium) atoms of the starting montmorillonite are at least partially replaced by long-chain secondary amino groups or other organic cations (bentonite modified with organic cations), for example, by dimethyldialkylammonium ions, in order to form a gel with the base oil.

[0016] In such bentonite greases, fumed silica (also known as fumed silica) is usually also included as a small percentage thickener in weight relative to the bentonite, and polyisobutylene is also present as a possible polymer additive to increase the structural strength of the gel or as an additional base oil, since it belongs to Group V (GPV) of the API classification of base oils for lubricants.

[0017] However, bentonite greases may exhibit high water washout values, for example above 18%, which makes them sensitive to humid conditions and / or the presence of water, if used.

[0018] It is known that bleaching earth (composed of an inorganic adsorbent material such as an aluminosilicate mineral, i.e. bentonite) is used in acid-activated form as an adsorbent material in pretreatment systems (e.g. bleaching) of crude bio-charges (such as vegetable oils, animal fats or their derivatives) for the production of biofuels in biorefineries (green refining processes).

[0019] The spent bleaching earth obtained from this process of pre-treatment of the biocharge contains not only inorganic adsorbent material but also organic material consisting of the original biocharge still adsorbed thereon and any impurities which may have been contained in the biocharge. The spent bleaching earth generally contains:

[0020] - 60 to 80% by weight of inorganic material consisting of bleaching earth;

[0021] - 20 to 36% by weight of organic material (for example vegetable oil), represented mainly by biomass, in addition to impurities still adsorbed on the soil;

[0022] - 0 to 4% moisture by weight.

[0023] To date, the treatment of the spent bleaching earth has envisaged the recovery of most of the oil still adsorbed in the bleaching earth by extraction with solvents.

[0024] Spent bleaching earth can also be valorized as a co-feedstock in compost or biogas plants, where the organic fraction of the spent earth is converted into biogas, with disposal costs ranging between 180 and 250 EUR / t.

[0025] However, these known methods of recycling or valorizing spent bleaching earth are expensive and, in the case of valorization in composting / biogas plants, do not involve complete reuse of the spent earth, which is contrary to the increasingly prevalent circular economy demands and to the growing need to reduce landfill disposal of by-products from industrial processes. Summary of the invention

[0026] It would therefore be highly desirable to find a process for valorizing spent bleaching earth which preferably does not require treatment of the spent bleaching earth with solvents, thereby at least saving on disposal costs.

[0027] It would also be highly desirable to have an infusible grease which exhibits lower water washout values ​​relative to infusible greases actually available on the market and which furthermore exhibits the combination of properties required of a bentonite grease, such as, for example, low tendency to weight loss and to fall off the seat (e.g. as assessed by means of a wheel bearing test), high resistance in use (e.g. as assessed by means of a roller shell stability test).

[0028] The applicant has now discovered that the spent bleaching earth can be valorized by using it as is in lubricating grease.

[0029] In fact, the Applicant has found that spent bleaching earths from purification processes of biocharges for the production of biofuels (green refineries) can be advantageously used as primary thickeners, even in large quantities, in the preparation of greases, in particular infusible greases, avoiding their handling and the need for expensive pretreatment with solvents to remove oil and / or impurities therefrom before their processing.

[0030] The formulation of grease (preferably infusible grease) containing the aforementioned spent bleaching earth also unexpectedly exhibits the following properties, thereby making the grease which is the object of the present invention an effective substitute for the bentonite grease known in the art, if not an improved infusible grease:

[0031] - excellent resistance to water washout, with water washout values ​​typically below 18 wt%, preferably below 13 wt%, more preferably below 10 wt%, and improved over bentonite greases;

[0032] - There is essentially no weight gain due to water incorporation;

[0033] - Excellent rust resistance compared to bearing steels (e.g., test of "Emcor" steel rust resistance);

[0034] - Good cold properties at temperatures below 0°C to -10°C (e.g. torque tests, flow pressure tests).

[0035] Therefore, a first object of the present invention is a lubricating grease comprising

[0036] - at least one base oil ("lubricant base oil"), or a mixture of base oils,

[0037] - at least one first thickener,

[0038] - an optional secondary thickener, preferably the amount of the secondary thickener is less than the amount of the first primary thickener,

[0039] and / or

[0040] - optional polymer additives which may have water-repellent properties,

[0041] in

[0042] - the first thickener is one or more spent bleaching earths and is present in an amount of up to 80% to 90% by weight relative to the total weight of the composition of the grease,

[0043] - said at least one or more base oils are fossil oils, synthetic oils, oils of biological origin, renewable oils and / or biodegradable oils or combinations thereof, preferably excluding UCO (used cooking oil) oils,

[0044] - The grease has a consistency classified according to the NLGI grade and is preferably a non-fusible grease.

[0045] In the description of the present invention, unless otherwise specified, the values ​​of the range include the extreme values ​​of the range.

[0046] In the specification of the present invention, unless otherwise specified, percentages (%) are understood to be based on weight.

[0047] In the description of the present invention, as a specific limitation, the term "comprise" also includes its meaning as "composed of".

[0048] In the present specification, the term "essentially composed of..." means

[0049] - The composition or formulation must include the listed ingredients

[0050] And refers to

[0051] - The composition or formulation is open to unlisted ingredients which do not materially affect the basic and innovative properties of the composition.

[0052] In the specification of the present invention, unless otherwise specified, "part(s)" and "part(s)" refer to parts by weight and parts by weight, respectively.

[0053] In the present description, the terms "thickener", "thickening agent" are used synonymously and are intended to mean generally solid compounds intended to at least increase the thickness and / or viscosity of the compositions containing them.

[0054] In the present description, a first "thickener" is intended to mean a thickener or thickener present in the grease as the main thickener: preferably in a higher concentration than other possible thickeners, if present.

[0055] In the present description, "spent bleaching earth" is intended to mean bleaching earth at the end of its use in the original biocharge purification process and which has not undergone any subsequent purification, recovery or treatment to remove contaminants such as oil.

[0056] The spent bleaching earth thus contains both typical inorganic adsorbent material (i.e. bentonite) of the original bleaching earth (i.e. unused) and organic material still adsorbed on the bleaching earth, said organic material mainly comprising biocharge (i.e. edible oil, e.g. vegetable oil, animal fat or derivatives thereof for the production of biofuels in a biorefinery (green refining process)) still adsorbed on the bleaching earth and possible impurities from the adsorbed original biocharge.

[0057] The spent bleaching earth that can be used in the grease according to the present invention can also be spent bleaching earth that has been subjected to a subsequent solvent extraction treatment to recover most of the organic material (e.g. oil still adsorbed on the bleaching earth). Such spent bleaching earth will hereinafter be referred to as "purified spent bleaching earth".

[0058] Unpurified spent bleaching earth typically contains 20 to 36% by weight of organic material consisting primarily of biomass (eg vegetable oil) and also of other impurities present in the biomass still adsorbed to the earth.

[0059] Purified spent bleaching earth contains relatively minor amounts of the above-mentioned organic materials, typically less than 20 to 36% by weight.

[0060] The presence of organic material (intended as the total material contained in the SBE that is neither inorganic material nor moisture) can be determined by means of, for example, XPS analysis, NMR or similar analysis known to be able to detect the elemental composition of the SBE and therefore also the presence of carbon atoms.

[0061] It should be understood that any other method known to those skilled in the art to detect the presence of organic material, such as determining solvent extraction (Sohxlet) of adsorbed oil by subtracting the weight of water (measured by Karl Fischer titration) and the weight of inorganic material (ashing residue to constant weight using a muffle furnace at 1000°C) may also be used without departing from the scope of the present invention.

[0062] Illustrative but non-limiting examples of unpurified spent bleaching earths are those from the pre-treatment of palm oil or other biomass such as, for example, castor oil, microbial oils, and animal oils and fats.

[0063] Other examples of vegetable oils or fats purified on bleaching earth may be sunflower oil, rapeseed oil, canola oil, palm oil, soybean oil, hemp oil, olive oil, linseed oil, peanut oil, mustard oil, coconut oil or the oil or fat contained in the wood pulp of pine trees ("tall oil") or mixtures thereof.

[0064] Examples of purified animal oils or fats on bleaching earth may be bacon, lard, tallow, milk fat and mixtures thereof. Recycled oils or fats from the food industry of both animal and vegetable origin may also be used.

[0065] Vegetable oils or fats purified on bleaching earth can also be obtained from plants selected by genetic manipulation.

[0066] Other examples of bioburden to be purified with bleaching earth may be by-products obtained by processing residuum (also called residue or slag) with solvent extraction of oil, such as for example "husk oil" from palm oil processing.

[0067] It should be understood that for the purposes of the present invention, the oils described above as biocharges are illustrative, rather than limiting, examples of organic components contained in spent bleaching earths useful in the greases of the present invention.

[0068] Spent bleaching earth from the biocharge pretreatment / purification process typically contains bentonite as inorganic material: however, it should be understood that spent bleaching earth consisting of other clay materials with high adsorption capacity besides bentonite may be used for the purposes of the present invention without departing from the scope of the present invention.

[0069] The typical composition of spent unpurified bleaching earth from a biofuel pretreatment process for biofuels can be exemplified but not limited to the following (weight % relative to the total weight of the unpurified bleaching earth):

[0070] 80 to 60% by weight of bentonite (mainly montmorillonite) as inorganic material;

[0071] 20 to 36% by weight of organic material, represented mainly by, for example, vegetable and / or animal oils and fats, C12+ hydrocarbons, phosphates, sulfates, metals, etc., which have been adsorbed onto the bleaching earth;

[0072] 0 to 4% moisture by weight.

[0073] It should be understood that for purposes of the present invention, the composition of the unpurified spent bleaching earth (SBE) described above is merely illustrative and not limiting, either in terms of percentages of components or in terms of the types of starting inorganic and organic materials adsorbed / retained in the bleaching earth.

[0074] It should also be understood that for the purposes of the present invention, as the primary thickener for the grease of the present invention, it is possible to use purified spent bleaching earth, i.e. spent bleaching earth which has undergone one or more subsequent treatments for partial recovery and / or removal of organic components (e.g. extraction of oil with a solvent), and which therefore has an organic material content of generally less than 20% by weight relative to the total weight of the purified bleaching earth (hereinafter referred to as purified spent bleaching earth), for example of about 10 to 15% by weight, but also lower values.

[0075] In a preferred embodiment, the spent bleaching earth used as the primary thickener for the grease of the present invention is that which is obtained at the end of a biocharge purification process and which has not been subjected to one or more subsequent contaminant recovery or removal treatments, such as extraction of the oil with a solvent (unpurified spent bleaching earth).

[0076] Hereinafter, descriptions made with reference to spent bleaching earth (hereinafter also referred to as SBE for brevity) are considered to apply both to unpurified spent bleaching earth and to purified spent bleaching earth without departing from the scope of the present invention.

[0077] For the purposes of the present invention, the grain size of the SBE (purified or unpurified) is not limiting and depends primarily on the grain size of the starting raw bleaching earth used in the biocharge purification process.

[0078] The starting raw bleaching earth used in the biocharge purification process may have a very variable surface area and / or particle size distribution (eg in the range of 0.8 μm to 2000 μm), but this is not binding for the purposes of the present invention.

[0079] As an example of the size range of the particles of the spent bleaching earth, a range within the range of 5 to 20 μm can be indicated.

[0080] Furthermore, the starting raw bleaching earth may have a pH (assessed in aqueous solution) which may be in the range of 2 to 8.6, but this is not binding for the purposes of the present invention.

[0081] Furthermore, the spent bleaching earth (SBE) useful in the grease (preferably the infusible grease) of the present invention may have an initial acidic pH evaluated by measuring the pH of an aqueous solution containing 10 wt. % of the spent bleaching earth.

[0082] In one embodiment, the spent bleaching earth (SBE) useful in the grease of the present invention has an initial acidic pH (assessed in aqueous solution using 1 g of SBE dispersed in 10 g of H2O and then measuring the pH of the resulting aqueous solution) typically in the range of 2 to 6 to 6.3.

[0083] The pH of the aforementioned aqueous solution containing SBE may vary, for example, between 2 and 9: in the case of an acidic or alkaline pH, it is advantageous to neutralize the pH of the spent bleaching earth (SBE) in order to avoid that the acidic or alkaline substances contained in the spent earth may, in the presence of water, form compounds corrosive to the metals that will come into contact with the grease containing said spent bleaching earth according to the invention.

[0084] In practice, the neutralization of the SBE with the alkaline or acidic substance (preferably an inorganic substance) can be carried out before the SBE is used in the formulation of the grease (for example before mixing with the base oil) or during the preparation of the formulation of the grease of the invention (for example after mixing with the base oil) without departing from the scope of the invention.

[0085] As examples of alkaline substances that can be used to neutralize the acidic pH of SBE, mention may be made of calcium carbonate, propylene carbonate, calcium hydroxide, preferably calcium carbonate or calcium hydroxide.

[0086] If the spent bleaching earth has an alkaline pH, for example a pH of about 9, it is preferably neutralized with a strong acid, more preferably a strong acid in aqueous solution, such as HCl solution, to achieve a pH of about 6 to 7.5.

[0087] The concentration of the strong acid in the above-mentioned aqueous solution which neutralizes the SBE is not binding for the purposes of the present invention and can be determined by a person skilled in the art without specific instruction.

[0088] In a preferred embodiment, the initially acidic spent bleaching earth is used in the grease of the present invention in neutralized form.

[0089] In the present context, the term "neutralized spent bleaching earth" is intended to mean a spent bleaching earth exhibiting a pH generally comprised between 6.5 and 7.5 (pH measured as the pH of an aqueous solution containing 10% by weight of said spent bleaching earth).

[0090] In particular, when it is desired to prepare a grease containing one or more mineral-type base oils, the acidic spent bleaching earth is preferably neutralized with calcium hydroxide, preferably with an aqueous solution of Ca(OH)2.

[0091] In another embodiment, when it is desired to prepare a grease with one or more ester base oils, it is preferred to neutralize the acidic spent bleaching earth with calcium carbonate in an aqueous solution.

[0092] Neutralization of spent bleaching earth is not a process related to obtaining bentonite modified with organic cations.

[0093] In a preferred embodiment, the spent bleaching earth, purified or unpurified, is present in the grease of the invention in neutralized form at a pH as defined above.

[0094] In the grease of the invention, the content of spent bleaching earth may advantageously be at least 10% by weight relative to the total weight of the grease composition.

[0095] In one embodiment, the content of SBE may advantageously range from 10% to 80% to 90% by weight relative to the total weight of the grease composition, the remainder up to 100% consisting solely of one or more base oils as defined above, preferably excluding UCO.

[0096] In another embodiment, the content of SBE ranges from 10% to 80% to 90% by weight relative to the total weight of the grease composition, the remainder up to 100% consisting of one or more base oils as defined above (preferably excluding UCO) and one or more additives selected from

[0097] - a second thickener,

[0098] - polymer additives that may have water-repellent properties,

[0099] and optionally one or more additives (additive package) selected from the group consisting of

[0100] - Anti-rust additives,

[0101] - anti-wear additives,

[0102] - Antioxidant additives,

[0103] -Copper corrosion inhibitor

[0104] Etc., for example, extreme pressure additives such as graphite, which will be described in detail below.

[0105] However, a total amount of more than 90 wt. % or less than 10 wt. % spent bleaching earth relative to the total weight of the grease composition may be used in the preparation of the grease according to the invention without departing from the scope of the invention.

[0106] In another embodiment, the content of SBE may advantageously range from 20% to 80% by weight relative to the total weight of the grease composition, the portion up to 100% being able to consist solely of one or more base oils as defined above, or of one or more base oils as defined above and of one or more additives as indicated above.

[0107] In another embodiment, the content of SBE may advantageously range from 20% by weight to an amount lower than 60% by weight, relative to the total weight of the grease composition, the remainder to 100% by weight being able to consist solely of one or more base oils as defined above, or of one or more base oils as defined above and of one or more additives as indicated above.

[0108] Considering the presence of impurities in spent bleaching earth, it has surprisingly been found that this spent bleaching earth can be used in lubricant formulations of greases to form a gel without causing negative phenomena such as, for example, reactions between the various components (considering the presence of metals in the SBE), phase separation (considering the presence of residual biological material contained in the SBE), etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0109] Figure 1 The consistency of the gel / paste of the present invention is shown to be of different appearance compared to the starting SBE which appears as a non-powdery solid. DETAILED DESCRIPTION

[0110] As mentioned above, the base oil used in the grease of the present invention may have different properties, in particular it can be selected from base oils having the following properties

[0111] - base oils of fossil nature, for example mineral oils (i.e. hydrocarbon mixtures obtained from crude oil by means of conventional refining processes or by means of moderate hydrogenation processes) of any viscosity cut (viscosity grade), for example fluid cut (SN 125÷170, typically 150), medium cut (SN 350÷600), bright stock (BS 150÷200) or mixtures thereof;

[0112] - base oils of synthetic nature, that is to say all types of base oils obtained by means of a synthetic process, for example by oligomerization and hydrogenation of olefins or polyol esters (such as, for example, PRIOLUBE 1965, PRIOLUBE 1963 or mixtures thereof);

[0113] - base oils of biological, renewable and / or biodegradable nature, such as palm oil, castor oil, microbial oils or other oils indicated above for biofeeds, preferably with the exception of UCO (WCO); polyalphaolefins functionalized with ester groups (PAO-esters) derived from the metathesis of vegetable oils;

[0114] or

[0115] - combinations thereof.

[0116] Waste oils UCO (used cooking oil) are preferably not used as base oils for the greases of the present invention, since these waste oils generally have carbonaceous residues, high freezing temperatures, corrosive compounds such as FFA (free fatty acids) and decomposition temperatures above 300°C, one or more of these characteristics representing a key element both for obtaining a grease with a high dropping point (i.e. above 350°C) and for applying said grease containing UCO on metal surfaces, in particular steel surfaces, in view of the high content of FFAs which are corrosive to metals.

[0117] In the grease composition according to the invention, when the second thickener is present, no UCO is present in the base oil forming the grease.

[0118] In addition, or as an alternative to the above, when the base oil is UCO, the grease according to the invention always comprises a polymer additive as defined above.

[0119] As examples of mineral oils that can be used as base oils, mention may advantageously be made of mineral oils of API classification, preferably group I (GPI), such as, for example, SN 500, BS150, SN 150, BS200 or mixtures thereof: Group I oils advantageously allow greases to reach NLGI grade consistencies of at least 1, but also higher.

[0120] As an alternative to Group I mineral base oils, API Group II and / or Group III mineral oils may also be used if it is desired to obtain a grease from a mineral oil having a lower consistency according to the NLGI classification.

[0121] Examples of synthetic base oils that can be used in the grease of the present invention are polyol esters (eg PRIOLUBE 1965, PRIOLUBE 1963) or mixtures thereof; polyalphaolefins (PAO): usually the synthetic base oils belong to Group IV of the API classification.

[0122] As examples of base oils of renewable origin which can be used in the greases of the invention, mention may be made of palm oil, castor oil, microbial oils, polyalphaolefins functionalized with ester groups (Pao-esters) derived from the metathesis of vegetable oils, estolides.

[0123] Group V base oils such as, for example, polymethacrylates, polyisobutylenes may also be used, but are usually mixed with Group I, II, III or IV base oils.

[0124] In a preferred embodiment, the at least one base oil employed in the grease of the present invention is a mineral base oil and / or an oil of renewable origin, preferably a mineral base oil of Group I, or a mixture of mineral base oils, preferably a mineral base oil of Group I (GPI), more preferably a mixture of SN 500 and BS150.

[0125] The viscosity of the base oil of the grease of the invention is not restrictive for the purposes of the invention, but the higher the viscosity, the higher the NLGI consistency of the grease that can be obtained.

[0126] The kinematic viscosity of the base oil suitable for forming the grease is, for example, 50 to 800 mm / s at 40°C. 2 / s, preferably 100 to 600 mm at 40°C 2 / s.

[0127] Therefore, the grease of the present invention may be composed of the following substances:

[0128] - one or more SBEs (unpurified or purified) and one or more base oils (two-component greases), preferably in addition to UCO;

[0129] - or it may comprise, in addition to SBE (purified or unpurified) and one or more base oils (preferably in addition to UCO), one or more additives chosen from a second thickener, polymer additives capable of improving the structural stability of the grease, possibly with water-repellent properties, other conventional additives for greases (such as anti-rust additives, anti-wear additives, anti-oxidation additives, copper corrosion inhibitors, etc., for example extreme pressure anti-wear additives as indicated in detail below, such as for example graphite).

[0130] In one embodiment, the grease (preferably an infusible grease) is formed by

[0131] - 70 to 80% by weight, preferably about 75 to 76% by weight, of spent bleaching earth as defined above, relative to the total weight of the grease composition,

[0132] and

[0133] - the remainder to 100% by weight of one or more base oils as defined above, preferably with the exception of UCO.

[0134] In another embodiment, the grease composition defined above provides that the above-mentioned remainder to 100% consists of a mixture of one or more base oils and one or more additives, preferably consists of a combination of one or more base oils and additives (additive package) selected from rust inhibitors, antiwear additives, antioxidant additives, copper corrosion inhibitors, extreme pressure antiwear additives and optional stabilizers.

[0135] As already mentioned, in the grease of the invention containing SBE and base oil, the following substances are advantageously present:

[0136] -Polymer additives

[0137] and / or

[0138] - A second thickener other than spent bleaching earth.

[0139] In one embodiment, the lubricating grease according to the invention comprises at least a polymer additive as defined above.

[0140] In a preferred embodiment, in the grease according to the invention containing SBE and a base oil, the polymer additive and the second thickener different from spent bleaching earth are advantageously present.

[0141] The second thickener (hereinafter also defined as thickener or viscosity modifier) ​​is selected from those substances commonly used in greases, such as for example fumed silica, preferably hydrophobic fumed silica, i.e. surface-modified with polydimethylsiloxane, without particular restrictions as to surface area, average particle size and particle size distribution.

[0142] Fumed silica has thixotropy due to its three-dimensional structure, and when the fumed silica is used as a thickener, the viscosity is increased.

[0143] The amount of this second thickener depends on the viscosity and / or consistency to be obtained of the final grease, in particular an infusible grease: generally, the amount of the second thickener may range from 0.5% to 7% by weight, preferably from 1% to 5% by weight, relative to the total weight of the grease composition.

[0144] In one embodiment, the amount of the second thickener is in the range of 1.5 wt % to 3 to 4 wt % relative to the total weight of the grease composition.

[0145] It should be understood that amounts less than 0.5% and greater than 7% of the secondary thickener may be employed without departing from the scope of the present invention.

[0146] In one embodiment, the grease (preferably an infusible grease) of the present invention comprises:

[0147] - 70 to 80 wt. %, preferably 75 to 80 wt. % of spent bleaching earth as defined above;

[0148] - 10 to 30% by weight, preferably 18 to 25% by weight, of one or more base oils as defined above, preferably one or more mineral oils, other than UCO;

[0149] - 0.5 to 7 wt. %, preferably 1.5 to 3 to 4 wt. %, more preferably 1.5 to 3 wt. % or 3 to 4 wt. % of a second thickener, preferably fumed silica,

[0150] The amounts of the aforementioned components are selected so that their sum is 100%.

[0151] If, in the grease according to the invention, in addition to the second thickener in the amounts indicated, one or more further additives are present, the total content of SBE will generally be lower than 75% by weight, preferably lower than 60%: furthermore, in such a grease formulation, the base oil or the mixture of base oils may advantageously be in the range from 10% to 50% by weight, preferably in the range from 15% to 30 to 35% by weight, relative to the total weight of the grease composition, and depending essentially on the grade of NLGI consistency to be achieved and the total amount of further additives required for the grease formulation.

[0152] However, it should be understood that in compositions where one or more other additives are present in addition to the secondary thickener, a base oil or base oil mixture in a total amount of less than 10 wt. % relative to the total weight of the grease composition may be used without departing from the scope of the present invention.

[0153] In addition to the secondary thickener, the one or more further additives that can be used in the grease composition according to the invention, preferably the infusible grease, are additives that allow achieving one or more conventional technical and performance specifications of greases, including infusible greases, if desired, such as, for example:

[0154] - anti-rust additives, in particular imidazolines, half esters of succinic acid (for example carboxyimidazoline sold under the trade name HITEC 536 by AFTON);

[0155] - antiwear additives such as dithiocarbamates (for example methylene-bis-dialkyl-dithiocarbamate sold under the trade name RC 6340 by RHEINE CHEMIE), dithiophosphoroesters (for example dithiophosphoroesters sold under the trade name IRGALUBE 353 by CIBA), thiophosphorothioates, phosphoramidates;

[0156] - antioxidant additives, in particular substituted diphenylamines (for example octylated / butylated diphenylamine sold under the trade name IRGANOX L 57 by BASF);

[0157] - polymer additives, possibly with water-repellent properties, to increase the structural stability of the gel, such as, for example, polyisobutylene, polymethyl methacrylate, typically with a low molecular weight (Mn), for example about 1300 g / mol;

[0158] - Stabilizers;

[0159] - copper corrosion inhibitors, such as, for example, benzotriazole derivatives, (for example a mixture of N,N-bis(2-ethylhexyl)-4-methyl-1h-benzotriazole-1-methylamine + N,N-bis(2-ethylhexyl)-5-methyl-1h-benzotriazole-1-methylamine, sold under the trade name IRGAMET 39 by CIBA);

[0160] Etc., such as, for example, extreme pressure and anti-wear additives, such as graphite.

[0161] Typically, the total content of other additives (except the second thickener) in the grease is lower than or equal to 40% by weight, preferably lower than 35% by weight, relative to the weight of the total grease composition.

[0162] The amount of each additive depends on the minimum amount at which the use of the additive begins to produce specific properties: generally, amounts starting from 0.01% by weight, preferably from 0.1% by weight, of each additive relative to the weight of the total grease composition are regarded as minimum amounts, although larger amounts can be used without departing from the scope of the invention.

[0163] As already mentioned above, among the various additives that can be used in the grease, preferably the infusible grease, according to the invention, compounds that contribute to improving the structural stability of the grease, such as polymer compounds, for example polyisobutylene, can be included, which also advantageously have water-repellent properties.

[0164] Other useful polymeric additives are those belonging to Group V of API base oils and may be, for example, polyalkyl methacrylates, in particular VISCOBASE 5-220 sold by EVONIK (kinematic viscosity at 100° C. = 460 to 500 cSt).

[0165] Typically, the amount of polymer additive possibly having water properties, preferably polyisobutylene, may range between 1 and 35% by weight, preferably between 7 and 35% by weight, preferably between 10 and 32% by weight, relative to the total weight of the grease composition.

[0166] In an alternative embodiment, the amount of polymer additive possibly having water properties, preferably polyisobutylene, may range between 1% and 7% by weight, preferably between 1.5% and 4% by weight, relative to the total weight of the composition of the grease.

[0167] The maximum amount of each other additive (except the SBE, the secondary thickener and the polymer additive) may be about 5 wt % relative to the total weight of the grease formulation, although this is not binding for the purposes of the present invention.

[0168] In a preferred embodiment, the grease comprises spent bleaching earth as defined above, a base oil (or a mixture of base oils) as defined above, fumed silica as a secondary thickener and polyisobutylene as a polymer additive.

[0169] In another preferred embodiment, the grease comprises the spent bleaching earth as defined above, the base oil (or mixture of base oils) as defined above, the secondary thickener (e.g. fumed silica) and the polymer additive (e.g. polyisobutylene) in the following amounts:

[0170] - 50 to 55% by weight of spent bleaching earth;

[0171] - 10 to 22% by weight of a base oil or base oil mixture as defined above, other than UCO

[0172] - 1.5 to 4% by weight of a second thickener, preferably fumed silica,

[0173] - 7 to 35% by weight, preferably 10 to 32% by weight, of polymer additives, preferably polyisobutylene,

[0174] The amounts of each of the aforementioned components can be chosen so that their sum is 100% of the total weight of the composition, or the remainder up to 100% of the total weight of the composition can be represented by one or more of the further conventional additives (additive package) for lubricating greases indicated above, chosen from anti-rust additives, anti-wear additives, antioxidant additives, copper corrosion inhibitors, extreme pressure anti-wear additives and optionally stabilizers.

[0175] Therefore, by changing the concentrations of base oil, SBE and other components (secondary thickener, polymer additive and other additives), the grease of the present invention (preferably infusible grease) can be formulated to have a NLGI consistency of Grade 0, or to have a greater consistency of Grade 1 or Grade 2, but can also have a higher consistency, such as Grade 3, Grade 4, without departing from the scope of the present invention.

[0176] In a preferred embodiment, the grease is infusible and has an NLGI consistency of greater than or equal to grade 1.

[0177] Thus, the grease according to the invention can be formulated to a content of up to 80% to 90% by weight, relative to its total weight, of compounds from the circular economy, with a significant share of renewable materials coming from organic materials present in the earth (about 30%) and the remaining potential share of up to 100% coming from base oils of renewable origin.

[0178] It is also surprising that the use of such spent bleaching earth, in the absence of additives known to impart water resistance, would result in low water washoff, even in greases containing SBE as the sole thickener.

[0179] Some embodiments are non-melting greases of the following compositions (weight % relative to the total weight of the composition of the grease):

[0180] Composition A:

[0181] 10% to 80% to 90% by weight, preferably 70% to 80% by weight, more preferably 75% to 80% by weight, of SBE relative to the total weight of the grease composition,

[0182] The remainder up to 100% consists exclusively of one or more base oils as defined above, preferably mineral oils, except UCO.

[0183] Composition B:

[0184] - 70 to 80% by weight, preferably 75 to 80% by weight, of spent bleaching earth;

[0185] - 10 to 30% by weight, preferably 18 to 25% by weight, of one or more base oils as defined above, other than UCO;

[0186] - 0.5 to 7% by weight, preferably 1.5 to 3 to 4% by weight, of a second thickener, preferably fumed silica,

[0187] The amounts of the aforementioned components are selected so that their sum is 100%.

[0188] Composition C:

[0189] - <75 wt. %, preferably <60 wt. % SBE;

[0190] - 10% to 50% by weight, preferably 15% to 30 to 35% by weight, of one or more base oils,

[0191] - 0.5 to 7% by weight, preferably 1.5 to 3 to 4% by weight, of a second thickener, preferably fumed silica,

[0192] - <35% by weight of one or more other additives selected from polymer additives, anti-rust additives, anti-wear additives, antioxidant additives, corrosion inhibitors,

[0193] The amounts of the aforementioned components are selected so that their sum is 100%.

[0194] Composition D:

[0195] - <75 wt. %, preferably 50 to 55 wt. % SBE,

[0196] - 10% to 50% by weight, preferably 10% to 22% by weight, of one or more base oils as defined above, other than UCO,

[0197] - 0.5 to 7% by weight, preferably 1.5 to 3 to 4% by weight, of a second thickener, preferably fumed silica,

[0198] - 1 to 35% by weight, preferably 7 to 35% by weight, of a polymer additive, preferably polyisobutylene;

[0199] - <35 wt. % of one or more other additives (additive package) selected from anti-rust additives, anti-wear additives, antioxidant additives, corrosion inhibitors, extreme pressure anti-wear additives,

[0200] The amounts of the aforementioned components are selected so that their sum is 100%.

[0201] Composition E:

[0202] - 50 to 60% by weight of SBE,

[0203] - 10% to 50% by weight, preferably 10% to 35% by weight, of one or more base oils as defined above, other than UCO,

[0204] - 1 to 4 wt. % of a second thickener, preferably fumed silica,

[0205] - 1 to 5% by weight of polymer additives, preferably polyisobutylene;

[0206] - <35 wt. % of one or more other additives (additive package, e.g. conventional additive package) selected from anti-rust additives, anti-wear additives, antioxidant additives, corrosion inhibitors, extreme pressure anti-wear additives (e.g. graphite),

[0207] The amounts of the aforementioned components are selected so that their sum is 100%.

[0208] The method for preparing the grease (preferably infusible grease) of the present invention comprises at least the following steps:

[0209] At least one or more spent bleaching earths as defined above are mixed with at least one or more base oils as defined above, preferably other than UCO, at atmospheric pressure and at a temperature lower than or equal to 100° C., preferably under ambient conditions.

[0210] The mixing can be carried out in any equipment provided with mixing and / or stirring equipment suitable for mixing semi-solid and very viscous products to obtain a processable mixture, such as equipment provided with mixing devices with high shear stress, such as, for example, planetary mixers, propeller mixers, mixers provided with twin-screw mixers, preferably mixers provided with twin-screw mixers.

[0211] Examples of stirring / mixing speeds may be speeds from 40 rpm to 1200 rpm.

[0212] Compared to the preparation of bentonite greases, which envisages a much more complex mode, this mode of preparation, which envisages simple mixing (for example in a mixer), offers great advantages: mixing temperatures above 100° C. and high working pressures, typically around 30 bar, but also exceeding, for example up to 200 bar, for homogenization.

[0213] The use of a mixer with a twin screw mixer has proven to be particularly advantageous since an infusible grease can be obtained by using only 75 to 80% by weight of spent bleaching earth of the grease, without the need for a secondary thickener such as fumed silica conventionally used in bentonite greases.

[0214] The grease of the invention thus obtained surprisingly also exhibits excellent properties of resistance to water washout (even in the absence of additives which also have water-repellent properties, such as polyisobutylene), infusibility and the ability to protect metals (e.g. copper, steel) from corrosion, since, in addition to passing the copper test, it also passes the Emcor test (steel test).

[0215] Furthermore, the greases of the invention show very high adhesion, generally higher than that of known bentonite greases: high adhesion is actually advantageous since it ensures that the grease remains in the valve seat when subjected to dynamic stresses during operation.

[0216] Furthermore, the high adhesion allows limiting the centrifugal losses of the grease, which are typical in some applications (eg gear motors).

[0217] In particular, the preparation process is advantageously carried out by carrying out a pH neutralization step of the spent bleaching earth prior to the SBE+base oil mixing step.

[0218] More specifically, the preparation process is advantageously carried out before the SBE+base oil mixing step and comprises the following steps:

[0219] (1) optionally homogenizing the particle size of the spent bleaching earth to make the particle size uniform, for example by means of a mill, to remove any inhomogeneities such as lumps, agglomerates, etc., resulting, for example, from the presence of water and biomass adsorbed on the spent bleaching earth;

[0220] (2) neutralizing the pH of the spent bleaching earth, optionally by using an alkaline or acidic substance;

[0221] (3) charging the spent bleaching earth, which may have been previously homogenized and / or made uniform in particle size, and / or optionally neutralized with an alkaline or acidic substance, into a mixing device, wherein the charging may be performed by using, for example, a conveyor auger;

[0222] (4) If the waste soil charged in step (3) has an acidic pH (e.g. 5.5) or an alkaline pH (e.g. 9), one or more neutralizing compounds are optionally charged to the mixing device, for example by adding an aqueous solution containing 10 to 35 wt % of an inorganic alkaline substance (e.g. Ca(OH)2), or an aqueous solution of an inorganic acid substance, and if any water is present, any water is removed.

[0223] Step (4) is preferably performed when the SBE has not previously undergone the neutralization treatment of step (2): however, it should be understood that step (4) may be performed even if step (2) has been performed without departing from the scope of the present invention.

[0224] Next, a step of adding one or more base oils and mixing SBE + base oil is carried out under stirring, hereinafter referred to as step (5). At the end of step (5), the following steps are envisaged:

[0225] - an optional subsequent addition step (step 5 bis) of adding a second thickener (e.g. fumed silica) while stirring the mixture of the components until a homogeneous mixture with a creamy appearance is obtained, or a homogeneous gel / paste is obtained, for example by continuing stirring for 4 hours;

[0226] and

[0227] - an optional addition step (6), after increasing the operating temperature in the mixing apparatus by at least preferably 40° C., more preferably 60° C., compared to the previous step, adding one or more further additives as indicated above and mixing simultaneously until a particle-free mixture having a creamy appearance or looking like a gel / paste is obtained, for example by continuing stirring for 1 hour.

[0228] The above steps (1) to (6) are all carried out under atmospheric pressure. In addition, the above steps (1) to (5-bis) are all carried out at ambient temperature.

[0229] In embodiments, even if there are no lumps visually, the step (1) of homogenizing the particle size is advantageously performed to ensure that the SBE is uniform in particle size prior to producing the grease.

[0230] In another embodiment, the neutralization steps (2) and / or (4) are advantageously performed to avoid possible corrosion of the production equipment.

[0231] The advantages of the grease of the invention obtained with the method according to the invention described above are manifold with respect to the known art.

[0232] The first advantage is that the amount of spent bleaching earth reused is much greater than the amount of bentonite used for producing grease (eg percentage >> 50%), unlike bentonite grease where the percentage of bentonite used is a maximum of 8 to 10%.

[0233] A second advantage is that the spent bleaching earths are reused as they are, without the need for post-treatment thereof, except for possible neutralization of their pH due to corrosion of the equipment materials.

[0234] Another advantage is that its production process is simple and simplified compared to that of bentonite greases, since it operates at atmospheric pressure, rather than under reduced pressure, and at temperatures below 100°C.

[0235] Furthermore, the process for producing the grease employed in the present invention allows improvements in certain performance characteristics, such as water washout, and improved resistance to water penetration due to the absence of weight gain due to water incorporation, compared to bentonite greases: these properties advantageously allow the use of the grease of the present invention in humid environments and / or in the presence of water.

[0236] The following are some illustrative but non-limiting examples of the present invention.

[0237] In the following examples, the physical properties have been determined using specified standard methods, but it should be understood that the same physical properties may be measured using equivalent methods belonging to different specifications / standards without departing from the scope of the present invention.

[0238] Examples

[0239] Material

[0240] -PRIOLUBE TM 1965: Polyol esters, marketed by Croda, with a kinematic viscosity at 40°C equal to 220 cSt;

[0241] -PRIOLUBE TM 1963: Polyol esters, marketed by Croda, with a kinematic viscosity at 40°C equal to 220 cSt;

[0242] - Fumed silica: Cabot's CAB-0-SIL TS 720, surface modified with polydimethylsiloxane to make it hydrophobic;

[0243] -PB 300 (denoted as such for brevity): H-300 additive (polybutene H 300), having a molecular weight (Mn) of 1300, sold by INEOS as a polymer additive (oligomer);

[0244] - BS150: a mineral base oil marketed by ENI SpA;

[0245] - SN 500: a mineral base oil marketed by ENI SpA;

[0246] - Type 1 spent bleaching earth (from the ENI SpA plant in Venice, used for bleaching palm oil), obtained from the acid-activated bentonite TONSIL 9194FF sold by Clariant: waste in the form of a non-powdery solid, containing about 287 g / kg (28.7%) of animal and vegetable oils and fats; about 540 mg / kg of C12+ heavy hydrocarbons; about 580 mg / kg of mineral oils; about 5 g / kg of metals; about 2.9 g / kg of phosphates and sulfates;

[0247] - Type 2 spent bleaching earth (sample from the ENI SpA plant in Gela for the treatment of bioburden), obtained from the acid-activated bentonite TONSIL 9194FF sold by Clariant: waste in the form of non-pulverulent solids, containing animal and vegetable oils and greases, C12+ heavy hydrocarbons, metals, phosphates and sulfates in quantities similar to those of SBE type 1 from the plant in Venice.

[0248] Characterization / Analytical methods

[0249] - Dropping point

[0250] According to the ASTM D566 method, it is the temperature at which a grease sample (if heated) will begin to flow through an opening.

[0251] -Consistency after 60 double strokes (dc)

[0252] It is a measure of the hardness of a grease and is assessed by measuring penetration according to ASTM D217-21a (10'mm). This test measures in tenths of a millimeter how deep a given cone sinks into a sample of grease.

[0253] Consistency is classified according to a scale developed by the NLGI (National Lubricating Grease Institute) and is reported below: Greases intended for bearings are generally NLGI 1, 2, or 3, the softer the grease, the lower the number.

[0254] NLGI Consistency Chart

[0255]

[0256] -Water flushing

[0257] The measurement is carried out according to the ASTM D 1264 method: The test (water washout) envisages coating a ball bearing placed in a housing with grease. Thereafter, the bearing is rotated at 600 rpm and subjected to a water jet for 1 hour at a temperature of 38°C. At the end of the test, the bearing is dried in an oven for 16 hours and then weighed to check any weight loss (wt%) due to water washout of the grease.

[0258] -Copper corrosion

[0259] The evaluation was performed by testing samples of the grease of the present invention according to ASTM D 4048.

[0260] -Kinematic viscosity

[0261] Evaluation was performed at 40°C according to ASTM D445 method.

[0262] Example 1

[0263] Evaluation of SBE gel / base oil formation and dropping point

[0264] To evaluate the effectiveness of spent bleaching earth in forming a gel and verify the formation of an infusible grease, a number of spent bleaching earth samples were blended with a base oil formed from a mixture of esters (PRIOLUBE 1965 and PRIOLUBE 1963) in the relative amounts reported in Table 1.

[0265] The kinematic viscosity of the base oil, consisting of a mixture of esters, at 40° C. is equal to 220 cSt.

[0266] The spent bleaching earth samples from the bleaching process of the biocharge consisting of palm oil (hereinafter referred to as Type 1 spent earth) were mixed as received with the aforementioned base oils in the percentages shown in Table 2 at ambient temperature and pressure.

[0267] The spent bleaching earth used (Type 1 - Sample CER020304) exhibited a pH equal to 3.2 evaluated in an aqueous solution containing 10% by weight of said spent bleaching earth.

[0268] Table 1

[0269] Ester mixture composition weight% PRIOLUBE 1965 46 PRIOLUBE 1963 54

[0270] Table 2

[0271] Composition of grease weight% Spent bleaching earth 80 PRIOLUBE 1965+PRIOLUBE 1963 20

[0272] The preparation of the gel was carried out according to the following procedure: Base oil (mixture of ester base oils) was added to type 1 spent bleaching earth in a becker under a hood at ambient temperature and atmospheric pressure, under stirring starting from 40 rpm up to 1200 rpm for 1 hour.

[0273] The mixer used was a laboratory mechanical mixer. RW 16BASIC.

[0274] Get the following Figure 1 A gel having the appearance shown in was then subjected to the tests shown in Table 3 to measure its consistency and dropping point.

[0275] Table 3

[0276] Gel properties result method NLGI consistency after 60dc 0 ASTM D 217 Dropping point, °C >350 ASTM D 566

[0277] The dropping point above 350° C. and the consistency of the final composition belonging to the NLGI grade of grease (grade 0, corresponding to a semifluid appearance) demonstrate the effective formation of a grease with a gel structure retaining oil at a high dropping point.

[0278] This means that the network formed by the spent bleaching earth is highly resistant to the outflow of the base oil retained therein, in a manner similar to what occurs in infusible bentonite greases.

[0279] Example 2

[0280] Preparation of infusible grease containing SBE and fumed silica

[0281] Using the same Type 1 spent bleaching earth, three grease formulations (Formulation 2, Formulation 3 and Formulation 5) were prepared according to the present invention, and their compositions are reported in Table 4.

[0282] The procedure and equipment followed for the preparation of the grease were identical to those reported in Example 1, with the difference that, after 1 hour of stirring, the fumed silica was subsequently added while keeping the composition stirred.

[0283] The obtained gel has Figure 1 The appearance of the samples was shown in Table 4 and then subjected to the tests shown in Table 4 to measure their consistency and dropping point.

[0284] Table 4

[0285]

[0286] It can be noted from Table 4 that the addition of fumed silica stiffens the gel, resulting in a "harder" grease, going from 0 consistency to 1 consistency.

[0287] Then, the amount of waste soil SBE was slightly increased to further increase the consistency.

[0288] Generally speaking, the thicker the grease, the better the grease's ability to remain in the bearing without creating excessive friction.

[0289] Example 3

[0290] Preparation of infusible grease using neutralized waste soil

[0291] By repeating the procedure of Example 2 and using the same Type 1 spent bleaching earth and the same mixture of esters as the base oil, a grease formulation containing an alkaline material was prepared.

[0292] Considering that the acidic pH of Type 1 spent bleaching earth (pH equal to 3.2 in 10 wt.% SBE aqueous solution) in the presence of water may be favorable for the corrosion of metals, three grease formulations were prepared by adding different alkaline substances to the aqueous solution, as reported in Table 6, relative to Example 2, in order to neutralize the pH of SBE.

[0293] After adding the base oil to the formulation, the alkaline material is added in the form of an aqueous solution.

[0294] Subsequently, water was removed from the product obtained by means of heating in an oven at 100° C. for 1 hour.

[0295] The alkaline substances in the 10% aqueous solution added to the formula are as follows

[0296] -Propylene carbonate (Formula 6)

[0297] -Calcium hydroxide (Formula 7)

[0298] -Calcium carbonate (Formula 8)

[0299] Get the following Figure 1 A gel having the appearance shown in was then subjected to the tests shown in Table 5 to measure its consistency and dropping point.

[0300] Table 5

[0301]

[0302] The pH of formulation 8 is close to neutral: the amount of alkaline substance in the formulation is such that no deterioration of the consistency and dropping point characteristics of the grease is observed compared to formulation 5, which has no alkaline substance added and has an acidic pH.

[0303] Example 4

[0304] A non-melting grease is prepared using mineral base oils, fumed silica and polymer additives and Water flushing test

[0305] Example 2 was repeated using the same type of spent bleaching earth (Type 1, Venice), except that a different base oil was used and an additional conventional polymer additive of polymeric nature was added, such as polyisobutylene 300, denoted PB 300 for simplicity.

[0306] As the base oil, a mixture of API Group I mineral base oils having substantially the same viscosity (at 40° C.) as the mixture of ester base oils of Examples 2 and 3 was used.

[0307] The mixture of mineral base oils used in this example has a kinematic viscosity at 40°C equal to 220 cSt (ASTM D455) and has the following composition:

[0308]

[0309] The various lubricating gels were prepared in the same manner as in Examples 1 to 3 above using ester base oil.

[0310] In one of the formulations (Formulation 16), the spent bleaching earth was neutralized using 3 g of Ca(OH) delivered in a minimum amount of water to achieve a neutral pH when the spent bleaching earth was present at 10% in aqueous solution prior to formulation with the other components of the grease, rather than during formulation of the grease itself.

[0311] The spent bleaching earth used in Formulations 12, 13 and 14 was not neutralized during or prior to the formulation of the grease.

[0312] Get the following Figure 1A gel having the appearance shown in was then subjected to the tests shown in Table 6 to measure its consistency, dropping point and water washout.

[0313] Table 6

[0314]

[0315] The data reported above show that the infusible greases according to the invention have excellent water washout resistance values.

[0316] Example 6

[0317] Preparation of infusible grease containing additives and different types of neutralized spent bleaching earth (soil sample 2)

[0318] A sample of spent bleaching earth (SBE) having a pH equal to 3.15 (measured in an aqueous solution containing 10 wt. % of SBE) from a bleaching treatment plant different from that shown in Example 1 (hereinafter referred to as type 2 spent earth) was pretreated before formulation with the other components of the grease by mixing the spent bleaching earth (SBE) sample with an aqueous solution of 33 wt. % of calcium hydroxide, bringing the pH of the aqueous solution containing 10 wt. % of SBE to a value of 7.

[0319] The final composition of the soil used is as follows

[0320] Composition of grease weight% Spent bleaching earth 88.5 <![CDATA[Aqueous solution of 23% Ca(OH)2]]> 11.5 pH of spent bleaching earth in 10% aqueous solution 7

[0321] Using the same mixing procedure described in the previous examples, the neutralized spent bleaching earth was then formulated with the mineral base oil SN 500 / BS 150 used in the previous examples and the additives (fumed silica and PB 300) already used in the previous examples.

[0322] Mixing was carried out in some cases using a laboratory planetary mixer, in other cases using a mixer equipped with a twin-screw mixer (ERWECAAR 402 200 g and Battagion 2 kg models).

[0323] Get the following Figure 1 A gel having the appearance shown in was then subjected to the tests shown in Table 7 to measure its consistency, dropping point and water washout.

[0324] Table 7

[0325]

[0326] Example 7

[0327] Non-melting grease also contains conventional additive package

[0328] To Formulation 19 of Example 6 was then added a standard additive package widely used in the formulation of industrial lubricants comprising antioxidants, rust inhibitors, anti-wear agents and copper corrosion inhibitors as defined below.

[0329] The additive package was added to Formulation 19 using a twin screw mixer.

[0330] The additive package contains the following substances:

[0331] - Antioxidant: IRGANOX L 57 (octylated / butylated diphenylamine) from BASF;

[0332] - Rust inhibitor: HITEC 536 (carboxy imidazoline) from AFTON;

[0333] - Antioxidant / antiwear agent: RC 6340 (methylene bis(dialkyl dithiocarbamate) from RHEINE CHEMIE;

[0334] - Antiwear extreme pressure agents: IRGALUBE 353 (dithiophosphate) and IRGALUBE 211 (triphenyl nonylatephosphorothionate or O,O-diphenyl-O-nonylphosphorothionate) from CIBA;

[0335] - Copper corrosion inhibitor: IRGAMET 39 from CIBA (N,N-bis(2-ethylhexyl)-4-methyl-1h-benzotriazole-1-methylamine + N,N-bis(2-ethylhexyl)-5-methyl-1h-benzotriazole-1-methylamine).

[0336] Table 8 reports the final composition after addition of the additive package (considered to be 100%) and the percentages of the components in the final grease.

[0337] Table 8

[0338]

[0339] According to the typical analytical specifications of lubricating grease, the obtained Figure 1 The greases having the gel appearance shown in were characterized and the results are reported in Table 9 below.

[0340] Table 9 – Grease Characterization Formulation 19a

[0341]

[0342]

[0343] It can be observed that the infusible grease obtained according to the invention has a combination of properties such as:

[0344] - Excellent water washout resistance and absence of weight gain due to water incorporation. The bentonite greases tested experienced a weight gain of about 20% due to water incorporation, whereas this phenomenon was not observed in the greases of the invention, as reported in the table below.

[0345]

[0346] Bentonite Grease 1: Product sold by Eni under the trade name GREASE NF 2;

[0347] Bentonite Grease 2: Product sold by the company Eni under the trade name GREASE 33FD.

[0348] The increase in the weight of bentonite grease due to the incorporation of water changes the chemical-physical and rheological properties of the grease, favoring corrosion phenomena and oxidation of the grease itself.

[0349] - Good anti-rust response, confirmed by excellent results in the "Emcor" test in distilled water, given by a performance value of 1, which corresponds to no more than three corrosion points, none of which has a diameter greater than 1 mm. The performance rating of the test ranges from 0 (no corrosion) to 5 (severe corrosion).

[0350] This is a particularly important test developed by SKF to verify the ability of a grease to prevent bearing rust: the better this property of the grease, the longer the bearing will function.

[0351] - Good cold properties, despite the presence of polyisobutylene polymers (whose viscosity increases at low temperatures and hinders the sliding of the grease), which proves that the grease can be used at temperatures as low as -10°C: this performance is measured by means of a "torque test". The grease-filled bearing is cooled to a given temperature at which the torque required to rotate the bearing, overcoming the resistance of the grease, is measured. The test result is expressed in two numbers, one being the maximum value recorded at the start of the test and the other being the continuous static torque once continuous speed has been reached. The higher these values, the lower the performance of the grease at the test temperature.

[0352] The test passes when the starting torque is ≤1000mN.m, and / or the working torque is ≤100mN.m: at -10°C the values ​​obtained are within the limits of the ISO 12924 grease specification and at -20°C the working torque is above the limits.

[0353] - The greases according to the invention have good cold properties which are also highlighted by the minimum operating temperature given by the value obtained by the "flow pressure" test, in which the pressure required to make the grease flow at low temperatures is determined. The results obtained both at 0°C and at -10°C are below the limit reported in ISO 12924, i.e. ≤1400 hPa.

[0354] - Excellent processing resistance, which is demonstrated by "roller shell stability", in which a grease sample is placed in a cylinder containing rollers and rotated for 2 hours at 35° C. The grease retains the same initial consistency even after processing.

[0355] The weight loss of the grease of the operating bearing was also evaluated with the aid of the "wheel hub bearing" test, which in any case gives an important indication of the tendency of the grease to flow out of the seat. In this case, the values ​​obtained were good.

[0356] Finally, it is important to note that generally the addition of additives will "soften the grease", so if a high consistency grease (e.g. NLGI 2) is desired, it is important to start with a higher consistency gel (spent bleaching earth + base oil).

[0357] Example 8

[0358] Preparation of non-melting greases with higher content of type 2 waste soil and base oils ISO VG with different viscosities

[0359] Three infusible greases were prepared by repeating the procedure of Example 6 (using the same type of twin screw mixer) using the same type but a higher percentage (75%) of neutralized spent bleaching earth than in Example 6, formulated with three base oils of increasing viscosity formed from three different mixtures with different viscosities (ISO VG 320, ISO VG 220 and ISO VG 100) (thus constituting the base oils of each of the following).

[0360] Mineral Base ISO VG 100 ISO VG 220 ISO VG 320 SN 500, weight % 94 46 25 BS150, weight% 6 54 75

[0361] Get the following Figure 1 A gel having the appearance shown in was then subjected to the tests shown in Table 10 to measure its consistency, dropping point, water washout, and copper corrosion.

[0362] Table 10

[0363]

[0364] It can be noted that for the same content of spent bleaching earth, if a base oil or a mixture of base oils with increased viscosity is used, a higher consistency and thus a higher NLGI grade can be obtained.

[0365] Furthermore, when large amounts of spent bleaching earth are used, such as greater than 50%, conventional additives may not be used to increase water resistance while achieving NLGI ratings greater than 1.

[0366] In particular, the grease of formulation 24 according to the invention exhibits the following properties in addition to infusibility and a high content of spent bleaching earth:

[0367] -High consistency

[0368] -High resistance to water washout in the absence of additives;

[0369] - Excellent compatibility with copper despite not containing specific corrosion inhibitors (1B: the larger the number, the worse the performance (i.e. corrosion resistance)).

Claims

1. A lubricating grease comprising at least one base oil or a mixture of base oils, at least one first thickener, an optional secondary thickener, preferably the amount of the secondary thickener is less than the amount of the first primary thickener; and / or Optional polymer additives which may have water-repellent properties, wherein the first thickener is one or more spent bleaching earths (SBE) and is present in an amount of 10% to 90% by weight relative to the total weight of the composition of the grease, and wherein the at least one or more base oils are fossil oils, synthetic oils, oils of biological origin, renewable oils and / or biodegradable oils or combinations thereof, preferably other than UCO (used cooking oil), The grease has a consistency classified according to the NLGI grade, The grease is preferably a non-melting grease.

2. The grease according to claim 1, wherein when the second thickener is present, no UCO is provided in the base oil forming the grease.

3. The grease according to claim 1 or 2, wherein the content of spent bleaching earth (SBE) is in the range of 10 to 80 wt. %, preferably in the range of 20 to 80 wt. %, relative to the total weight of the grease composition, The remainder up to 100% can consist only of one or more base oils, preferably excluding UCO, or can consist of one or more base oils, preferably excluding UCO, and one or more additives chosen from a second thickener, a polymer additive possibly having water-repellent properties, an anti-rust additive, an anti-wear additive, an anti-oxidation additive, a copper corrosion inhibitor.

4. The lubricating grease according to any one of the preceding claims 1 to 3, wherein the at least one base oil is a mineral base oil, preferably a base oil of API Group I, or a mixture of mineral base oils, preferably a mixture of mineral base oils of API Group I.

5. The lubricating grease according to any one of the preceding claims 1 to 3, wherein at least the base oil is a synthetic base oil or a mixture of synthetic base oils.

6. A grease according to any one of the preceding claims 1 to 5, wherein the total amount of spent bleaching earth is in the range between 70 and 80 wt. %, preferably about 75 to 76 wt. %, relative to the total weight of the grease composition, The remainder up to 100% can consist of one or more base oils other than UCO, or one or more base oils other than UCO and one or more additives selected from anti-rust additives, anti-wear additives, anti-oxidation additives, copper corrosion inhibitors.

7. The lubricating grease according to any one of the preceding claims 1 to 5, further comprising the polymer additive which may have water-repellent properties.

8. The grease according to any one of claims 1 to 5, 7, wherein the second thickener is also present in an amount ranging from 0.5 wt.% to 7 wt.%, preferably ranging from 1 wt.% to 5 wt.%, more preferably ranging from 1.5 wt.% to 3 to 4 wt.%, relative to the total weight of the grease composition.

9. The grease of claim 8, wherein the second thickener is fumed silica.

10. The lubricating grease according to any one of the preceding claims 1 to 5, 7 to 9, comprising: - 70 to 80 wt. %, preferably 75 to 80 wt. % of said spent bleaching earth; - 10 to 30% by weight, preferably 18 to 25% by weight, of one or more of said base oils other than UCO, preferably one or more mineral oils or synthetic oils, more preferably mineral oil; - 0.5 to 7 wt. %, preferably 1.5 to 3 to 4 wt. %, more preferably 1.5 to 3 wt. % or 3 to 4 wt. % of said second thickener, preferably fumed silica, The amounts of the aforementioned components are selected so that their sum is 100%.

11. The grease according to any one of the preceding claims 1 to 5, 7 to 10, further comprising the polymer additive which may have water-repellent properties in an amount ranging from 1% to 35% by weight, preferably ranging from 7% to 35% by weight, relative to the total weight of the grease composition.

12. The lubricating grease according to any one of the preceding claims 1 to 5, 7 to 9, 11, comprising: - 50 to 55% by weight of spent bleaching earth; - 10 to 22% by weight of a base oil or base oil mixture other than UCO, - 1.5 to 4% by weight of a second thickener, preferably fumed silica, - 7 to 35% by weight, preferably 10 to 32% by weight, of polymer additives, preferably polyisobutylene, The amount of each of the aforementioned components is selected so that their sum is 100% of the total weight of the composition, or the remainder up to 100% of the total weight of the composition can be represented by one or more other additives selected from anti-rust additives, anti-wear additives, anti-oxidation additives, copper corrosion inhibitors.

13. A lubricating grease according to any one of the preceding claims 1 to 12, wherein the spent bleaching earth is in a neutralized form with respect to pH.

14. The lubricating grease according to any one of the preceding claims 1 to 5, 7 to 13, comprising (Composition C): - <75 wt. %, preferably <60 wt. % SBE; - 10% to 50% by weight, preferably 15% to 30 to 35% by weight, of one or more base oils; - 0.5 to 7% by weight, preferably 1.5 to 3 to 4% by weight, of said second thickener, preferably fumed silica, - <35 wt. % of one or more other additives selected from polymer additives, anti-rust additives, anti-wear additives, antioxidant additives, corrosion inhibitors, The amounts of the aforementioned components are selected so that their sum is 100%.

15. A method for preparing the grease according to any one of claims 1 to 14, comprising at least the following steps: One or more spent bleaching earths are mixed with one or more base oils, preferably other than UCO, at atmospheric pressure and at a temperature less than or equal to 100°C.

16. The method according to claim 15, wherein the mixing is performed using a mixer equipped with a high shear mixing device, preferably a twin-screw mixer.

17. The method according to claim 15 or 16, wherein before the step of mixing the SBE with the at least one base oil, the following steps are carried out: (1) optionally homogenizing the particle size of the spent bleaching earth (SBE) to remove possible inhomogeneities (lumps); (2) optionally neutralizing the spent bleaching earth with an alkaline or acidic substance; (3) charging the spent bleaching earth, which has optionally been homogenized with respect to particle size and / or neutralized with an alkaline or acidic substance, into a mixing device; (4) If the spent bleaching earth charged in step (3) has an acidic pH or an alkaline pH, one or more compounds capable of neutralizing the pH of the SBE are optionally charged to the mixing device, and water, if present, is optionally removed.

18. The method according to any one of claims 15 to 17, wherein at the end of said mixing step of said one or more base oils and spent bleaching earth (SBE), further providing - an optional subsequent addition step (5 bis) of adding a second thickener, such as fumed silica, while stirring the mixture of the components until a homogeneous mixture with a creamy appearance is obtained, or a homogeneous gel / paste is obtained; and - an optional addition step (6), after increasing the operating temperature in the mixing device to preferably at least 40° C. compared to the previous step, adding one or more further additives according to any one of claims 1 to 13 and maintaining the mixing until a mixture with a creamy appearance or a gel / paste-like appearance and without particles is obtained.

19. Use of an infusible grease comprising spent bleaching earth according to any one of the preceding claims 1 to 14 for lubricating moving mechanical components, such as bearings, in particular bearings with rotating elements, smooth bearings; gears, in particular open gears, preferably operating at high temperatures, for example over 200° C., in particular at temperatures typical of processes in cement plants and the steel industry.

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