BIODEGRADABLE LUBRICANTS

Description

[0001] The present invention relates to the field of greases, particularly for the off-road, agricultural and wind power markets, exhibiting improved anti-wear and extreme pressure properties and high biodegradability. technical field

[0002] There are many applications where liquid lubricants are unsuitable because they "drift" from the lubrication point. These include, in particular, bearings (ball, roller, needle), rolling and sliding bearings, open gears, wire ropes and chain drives, and more generally, applications without a sealing system.

[0003] For these applications, lubricating greases are used, which are solid or semi-fluid substances resulting from the dispersion of a thickener in a liquid lubricant, possibly incorporating additives that give them particular properties.

[0004] The greases currently used generally include fossil-based mineral oils that do not exhibit high biodegradability. US document 2018 / 0030367 discloses a grease composition.

[0005] Manufacturers are increasingly seeking to formulate biodegradable grease compositions, particularly for greases that need to be renewed regularly, for example for applications involving a high risk of leakage.

[0006] US document 2021 / 0277323 discloses a lubricating grease with a low environmental impact.

[0007] In certain applications, particularly for off-road markets (construction or agricultural equipment) and wind power markets (wind turbines), increasingly powerful machines are subjected to increasingly severe conditions and require significant performance gains in extreme-pressure properties from their lubrication products, in addition to biodegradability for example.

[0008] It is therefore an object of the present invention to provide a grease composition comprising a base oil and a thickener both biodegradable, grease which also exhibits excellent anti-wear and extreme-pressure properties and good stickiness. Summary of the invention

[0009] More specifically, the present invention relates to a fat composition comprising, relative to the total weight of the fat composition: a) 70 to 95% by weight of base oil(s), each having a 28-day biodegradability of at least 60%, as measured according to OECD 301B standard; b) 1 to 20% by weight, preferably 2 to 20% by weight, of thickener(s) selected from fatty acid metal salts, each thickener having a 28-day biodegradability of at least 60%, as measured according to OECD 301B standard; c) 0.5 to 10% by weight of calcium carbonate having a D50 particle size greater than or equal to 3 µm and a D90 particle size greater than or equal to 10 µm.

[0010] According to one embodiment, the fat composition according to the invention is characterized in that it has a 28-day biodegradability of at least 60%, calculated from the 28-day biodegradability of the base oil(s) and thickener(s), the 28-day biodegradability of the base oil(s) and thickener(s) being measured according to OECD method 301B.

[0011] Preferably, the thickener is chosen from lithium salts and possibly hydroxylated fatty acids, calcium salts and possibly hydroxylated fatty acids and mixtures thereof, preferably from lithium salts and possibly hydroxylated fatty acids, preferably from lithium 12-hydroxystearate.

[0012] Preferably, base oils are chosen from ester oils.

[0013] Preferably, calcium carbonate has a D50 particle size ranging from 3 to 20 µm and a D90 particle size ranging from 10 to 50 µm.

[0014] Preferably, the grease composition according to the invention further comprises at least one extreme-pressure additive, preferably in an amount ranging from 1 to 15% by weight, relative to the total weight of the composition.

[0015] Preferably, the grease composition according to the invention is free from anti-wear additives of the amine phosphate type, and of the zinc diamyl dithiocarbamate type and of the zinc dialkyl dithiophosphate type.

[0016] Preferably, the fat composition according to the invention comprises at least 40% by weight of carbon of biological origin, preferably at least 45% by weight of carbon of biological origin, relative to the total weight of carbon atoms in the composition.

[0017] The invention also relates to the use of the grease composition according to the invention, in a non-road, agricultural or wind power device.

[0018] Preferably, the non-road, agricultural or wind-powered device is chosen from construction equipment, agricultural machinery and wind turbines.

[0019] The grease composition according to the invention exhibits excellent anti-wear and extreme-pressure properties and good adhesive power, even in the absence of anti-wear additives.

[0020] In particular, the grease composition according to the invention will typically exhibit the following properties: Extreme pressure properties in the 4-ball test according to ASTM D2596 of 500 kgf. Low wear of approximately 0.5 mm according to ASTM D2266. Water spray-off result of less than 30% loss according to ASTM D4049.

[0021] The fat composition according to the invention will typically exhibit high biodegradability.

[0022] In the following text, the expressions "between ... and ...", "ranging from ... to ..." and "varying from ... to ..." are equivalent and are meant to mean that the boundaries are included, unless otherwise stated.

[0023] Unless otherwise stated, quantities in a product are expressed by weight, relative to the total weight of the product. Detailed description

[0024] The present invention relates to a fat composition comprising, relative to the total weight of the fat composition: a) 70 to 95% by weight of base oil(s), each having a 28-day biodegradability of at least 60%, as measured according to OECD 301B standard; b) 2 to 20% by weight of thickener(s) selected from fatty acid metal salts, each thickener having a 28-day biodegradability of at least 60%, as measured according to OECD 301B standard; c) 0.5 to 10% by weight of calcium carbonate having a D50 particle size greater than or equal to 3 µm and a D90 particle size greater than or equal to 10 µm. possibly 1 to 15% by weight of additive(s), said additives being different from the base oils a), different from the thickeners b) and different from calcium carbonate c).

[0025] Preferably, the fat composition according to the invention is biodegradable.

[0026] For the purposes of the present invention, a "compound" shall be said to be "biodegradable" if it exhibits a 28-day biodegradability of at least 60%, as measured according to OECD 301B standard.

[0027] For the purposes of the present invention, the "fat composition" shall be said to be "biodegradable" if the biodegradability calculated from the biodegradability of the base oil(s) and thickener(s) weighted by the proportions of said base oil(s) and thickener(s) in said fat composition is at least 60% at 28 days.

[0028] For example, if the fat composition includes: v% by weight of a base oil having a biodegradability Bv% at 28 days, measured according to OECD 301B, y% by weight of a base oil having a biodegradability By% at 28 days, measured according to OECD 301B, z% by weight of a thickener having a biodegradability Bz% at 28 days measured according to OECD 301B, q% by weight of calcium carbonate, t% by weight of additive(s), then the 28-day biodegradability of the fat composition, Bc expressed as a percentage, will be calculated as follows: Bc = v% × Bv + y% × By + z% × Bz. Base oil(s)

[0029] The grease composition implemented according to the invention comprises one or more biodegradable base oils.

[0030] Preferably, the fat composition includes at least one base oil of renewable origin, for example of vegetable or animal origin.

[0031] Preferably, base oils of renewable origin represent at least 75% by weight of the total weight of base oils.

[0032] According to one embodiment, all the base oils in the grease composition according to the invention exhibit a 28-day biodegradability of at least 60%, as measured according to OECD 301B.

[0033] It can be a mixture of several base oils, for example a mixture of two, three, or four base oils.

[0034] According to one embodiment, the grease composition comprises at least one ester-type base oil.

[0035] Preferably, the ester-type base oil(s) represent at least 50% by weight, preferably at least 70% by weight, of the total weight of the base oils.

[0036] Among the esters that can be used as a base oil, we can mention polyol esters.

[0037] Polyol esters, which can be used as base oil, are for example diesters, triesters, tetraesters or complex esters comprising more than four ester functions.

[0038] The acids that can be used to form esters are monocarboxylic acids or dicarboxylic acids.

[0039] Preferably, monocarboxylic acids have from 3 to 22 carbon atoms, more preferably from 4 to 20, even more preferably from 6 to 18, even more preferably from 8 to 16, even more preferably from 10 to 12.

[0040] Examples include hexanoic, octanoic, 2-ethylhexanoic, isooctanoic, nonanoic, decanoic, isodecanoic, oleic, and stearic acids. Saturated acids without unsaturations are preferred.

[0041] Preferably, dicarboxylic acids have from 3 to 22 carbon atoms, more preferably from 4 to 20, even more preferably from 6 to 18, even more preferably from 8 to 16, even more preferably from 10 to 12. Examples include succinic, adipic, azelaic, and sebacic acids.

[0042] Alcohols that can be used to form esters include monoalcohols (diesters formed with dicarboxylic acids), dialcohols, trialcohols, and tetraalcohols. Preferred alcohols are polyols such as neopentyl glycol, trimethylolpropane, and pentaerythritol.

[0043] The base oil or base oil mixture preferably has a viscosity at 40°C greater than or equal to 100 cSt, preferably greater than or equal to 200 cSt, preferably even greater than or equal to 300 cSt, preferably even greater than or equal to 400 cSt, preferably even greater than or equal to 500 cSt.

[0044] Viscosity is preferably measured according to ASTM D445.

[0045] The base oil(s) preferably represent 70 to 95% by weight, preferably 75 to 90% by weight, of the total weight of the fat composition.

[0046] The base oils that can be used in the present invention are commercially available products. Thickening

[0047] The fat composition according to the invention comprises at least one thickener selected from metallic salts of fatty acids.

[0048] Preferably, the grease composition according to the invention is free of polyurea-type thickeners.

[0049] Metallic salts of fatty acids may be chosen from metallic salts of mono-fatty acids or metallic salts of di-fatty acids, said mono-acids or di-acids preferably comprising from 8 to 28 carbon atoms.

[0050] Long-chain fatty acids are preferred, typically comprising 10 to 28 carbon atoms, saturated or unsaturated, possibly hydroxylated.

[0051] Long-chain fatty acids (typically comprising 10 to 28 carbon atoms) include, for example, capric, lauric, myristic, palmitic, stearic, arachidic, behenic, oleic, linoleic, and erucic acids, and their hydroxylated derivatives. 12-Hydroxystearic acid is the preferred derivative.

[0052] Lithium 12-hydroxystearate is the preferred thickener for the fat composition according to the invention.

[0053] These long-chain fatty acids generally come from vegetable oils, for example palm oil, castor oil, rapeseed oil, sunflower oil,... or from animal fats (tallow, whale oil...).

[0054] So-called simple soaps can be made using one or more long-chain fatty acids, typically monoacids.

[0055] Complex soaps can also be formed using one or more long-chain fatty acids in combination with one or more short-chain dicarboxylic acids comprising a maximum of 10 carbon atoms. In one embodiment, the short-chain carboxylic acids are selected from mono- and dicarboxylic acids preferably comprising 3 to 10 carbon atoms.

[0056] The saponifying agent used to make soap may be a metallic compound of lithium, sodium, calcium, aluminum, preferably lithium and calcium, and preferably a hydroxide, oxide or carbonate of these metals.

[0057] One or more metallic compounds, having or not the same metallic cation, can be used in the greases according to the invention. Lithium soaps can thus be combined with calcium soaps in a smaller proportion.

[0058] The thickener(s) preferably represent 3 to 20% by weight, preferably 4 to 15% by weight, preferably 5 to 12% by weight, of the total weight of the fat composition.

[0059] The thickeners that can be used in the present invention are commercially available products. Calcium carbonate

[0060] The grease composition according to the invention comprises calcium carbonate having a D50 particle size greater than or equal to 3 µm and a D90 particle size greater than or equal to 10 µm.

[0061] For the purposes of the present invention, particles having a D50 particle size of X µm means that 50% by volume of the particles have a size less than X µm and that 50% by volume of the particles have a size greater than X µm.

[0062] For the purposes of the present invention, particles having a D90 particle size of X µm means that 90% by volume of the particles have a size less than X µm and that 10% by volume of the particles have a size greater than X µm.

[0063] The D50 and D90 particle sizes can be measured by laser diffraction, using any method well known to those skilled in the art. An example of such a method is detailed in the experimental section.

[0064] According to one embodiment, the calcium carbonate has a D50 particle size ranging from 3 to 20 µm and a D90 particle size ranging from 10 to 50 µm, preferably a D50 particle size ranging from 4 to 15 µm and a D90 particle size ranging from 10 to 40 µm.

[0065] According to one embodiment, calcium carbonate has a D50 particle size ranging from 5 to 10 µm and a D90 particle size ranging from 10 to 30 µm.

[0066] The inventors discovered that calcium carbonate having a particle size as defined in the present invention makes it possible to obtain both good anti-wear properties and good extreme-pressure properties.

[0067] In the state of the art, it is a calcium carbonate with a much smaller particle size (nanometric) that is generally used as an anti-wear agent.

[0068] Calcium carbonate represents from 0.5 to 10% by weight, preferably from 1 to 5% by weight, preferably still from 2 to 4% by weight of the total weight of the fat composition according to the invention.

[0069] The calcium carbonate particles that can be used in the present invention are commercially available products. Addendum(s)

[0070] The fat composition according to the invention may include one or more complementary additives different from the base oils a), different from the thickeners b) and different from the calcium carbonate c), defined previously.

[0071] According to one embodiment, the additional additive(s) are chosen from extreme-pressure additives, antioxidant additives, anti-corrosion additives, metal passivating additives, and mixtures thereof.

[0072] These additives can be introduced individually and / or in the form of a mixture.

[0073] The fat composition according to the invention may include at least one antioxidant additive. The antioxidant additive may be selected from phenolic or amino-type antioxidants.

[0074] Antioxidant additives can be selected from among sterically hindered phenols, sterically hindered phenol esters, and sterically hindered phenols containing a thioether bridge, and mixtures thereof. Amino compounds are another class of antioxidant additives that can be used, possibly in combination with phenolic antioxidant additives.Examples of amine compounds are aromatic amines, for example, aromatic amines of the formula NR10R11R12, where R10 represents an aliphatic or aromatic group, possibly substituted, R11 represents an aromatic group, possibly substituted, R12 represents a hydrogen atom, an alkyl group, an aryl group, or a group of the formula R13S(O)zR14, where R13 represents an alkylene or alkenylene group, R14 represents an alkyl, alkenyl, or aryl group, and z represents 0, 1, or 2. Examples of amine-type antioxidants include diphenylamines, diphenylamines substituted with at least one alkyl group at C1-C12, and N,N'-dialkyl-aryl-diamines and their mixtures.

[0075] The fat composition according to the invention may comprise from 0.05 to 5% by weight, preferably from 0.1 to 4% by weight or from 0.2 to 2% by weight of antioxidant agent, relative to the total weight of the composition.

[0076] According to one embodiment, the grease composition includes at least one extreme-pressure additive.

[0077] According to one embodiment, the fat composition comprises 2 to 10% by weight of at least one extreme-pressure additive, relative to the total weight of the fat composition.

[0078] Preferably, the extreme-pressure additive is chosen from sulfur olefins, sulfur fatty acid esters, and mixtures thereof.

[0079] Sulfur-containing fatty acid esters can be obtained by sulfurizing fatty acid esters. These fatty acid esters are obtained by reaction between one or more fatty acids and alcohols of all kinds, or by transesterification between one or more fatty acid esters and alcohols of all kinds.

[0080] By ester of sulfur fatty acid, we mean an ester of at least one sulfur fatty acid, it being understood that it is most often an ester of a mixture of sulfur fatty acids.

[0081] The fatty acids that can be used to form sulfur-containing fatty acid esters are all fatty acids comprising 6 to 24 carbon atoms, preferably 14 to 22 carbon atoms, and more preferably 16 to 20 carbon atoms. Fatty acids comprising 18 carbon atoms are the major fatty acids, meaning they are present at a mass concentration of at least 50% of the total mass of the sulfur-containing fatty acid ester.

[0082] Sulfur fatty acid esters may be sulfur fatty acid monoesters, sulfur fatty acid diesters, sulfur fatty acid triesters or sulfur fatty acid polyesters taken alone or in mixture.

[0083] Preferred monoesters of sulfur-containing fatty acids are C1-C4 alkyl monoesters, such as methyl monoesters, ethyl monoesters, n-propyl monoesters, i-propyl monoesters, n-butyl monoesters, s-butyl monoesters, and t-butyl monoesters. Preferably, the monoester is a methyl monoester. Preferably, the sulfur-containing fatty acid ester is a methyl ester of a sulfur-containing fatty acid.

[0084] As an example of sulfur fatty acid triesters, we can cite sulfur fatty acid triglycerides which will be completely or partially esterified and will therefore possibly include, in addition to triesters, diesters and / or monoesters.

[0085] Examples of sulfur-containing fatty acid polyesters include pentaerythritol esters of sulfur-containing fatty acids.

[0086] Sulfur-containing olefins are preferably sulfurized olefins and can be obtained, for example, by the sulfuration reaction of olefins with sulfur, hydrogen sulfide, or hydrated alkali metal sulfides, such as sodium sulfide. An example of a process for preparing such sulfur-containing olefins is described in US patents 4344854 and 5135670. Many olefins can be sulfurized in this way. Preferably, sulfur-containing olefins are manufactured from isobutylene, diisobutylene, triisobutylene, tripropylene, or tetrapropylene.

[0087] According to a preferred embodiment, the sulfur olefins are selected from among the sulfurized isobutylene (in English "Sulfurized IsoButylenes" or SIB).

[0088] According to one embodiment, the grease composition according to the invention does not comprise a polymer.

[0089] The inventors have indeed discovered that the grease composition according to the invention has good sticking power without the addition of a polymer-type additive.

[0090] According to one embodiment, the grease composition according to the invention is substantially free of amine phosphate type anti-wear, zinc diamyl dithiocarbamate type and zinc dialkyl dithiophosphate type.

[0091] By "substantially free" we mean a proportion less than 0.01% by weight.

[0092] According to one embodiment, the grease composition according to the invention is free of amine phosphate type anti-wear, free of zinc diamyl dithiocarbamate type anti-wear and free of zinc dialkyl dithiophosphate type anti-wear.

[0093] According to one embodiment, the grease composition is substantially free of anti-wear additives, preferably totally free of anti-wear additives.

[0094] The inventors have indeed discovered that the grease composition according to the invention has good anti-wear properties without the addition of an anti-wear additive, in particular of the amine phosphate type, zinc diamyl dithiocarbamate type and / or zinc dialkyl dithiophosphate type.

[0095] According to one embodiment, the fat composition according to the invention comprises, relative to the total weight of the fat composition: 70 to 95% by weight, preferably 75 to 90% by weight, of base oil(s), 3 to 20% by weight, preferably 4 to 15% by weight of thickener(s) selected from lithium salts and fatty acid possibly hydroxylated comprising 10 to 28 carbon atoms, 0.5 to 10% by weight, preferably 1 to 5% by weight of calcium carbonate having a D50 particle size of 3 to 20 µm and a D90 particle size of 10 to 50 µm.

[0096] According to one embodiment, the fat composition according to the invention comprises, relative to the total weight of the fat composition: 70 to 95% by weight, preferably 75 to 90% by weight, of base oil(s), 3 to 20% by weight, preferably 4 to 15% by weight of thickener(s) chosen from lithium salts and fatty acid possibly hydroxylated comprising 10 to 28 carbon atoms, 0.5 to 10% by weight, preferably 1 to 5% by weight of calcium carbonate having a D50 particle size of 4 to 15 µm and a D90 particle size of 10 to 40 µm.

[0097] According to one embodiment, the fat composition according to the invention comprises, relative to the total weight of the fat composition: 70 to 95% by weight, preferably 75 to 90% by weight, of base oil(s) comprising at least one ester oil, 3 to 20% by weight, preferably 4 to 15% by weight of thickener(s) comprising at least one lithium salt and fatty acid possibly hydroxylated comprising 10 to 28 carbon atoms, 0.5 to 10% by weight, preferably 1 to 5% by weight of calcium carbonate.

[0098] According to one embodiment, the fat composition according to the invention comprises, relative to the total weight of the fat composition: 70 to 95% by weight, preferably 75 to 90% by weight, of base oil(s) comprising at least one ester oil, 3 to 20% by weight, preferably 4 to 15% by weight of thickener(s) comprising at least lithium 12-hydroxystearate, 0.5 to 10% by weight, preferably 1 to 5% by weight of calcium carbonate having a D50 particle size of 3 to 20 µm and a D90 particle size of 10 to 50 µm.

[0099] According to one embodiment, the fat composition according to the invention comprises, relative to the total weight of the fat composition: 70 to 95% by weight, preferably 75 to 90% by weight, of base oil(s) comprising at least one ester oil, 3 to 20% by weight, preferably 4 to 15% by weight of thickener(s) comprising at least lithium 12-hydroxystearate, 0.5 to 10% by weight, preferably 1 to 5% by weight of calcium carbonate having a D50 particle size of 4 to 15 µm and a D90 particle size of 10 to 40 µm.

[0100] According to one embodiment, the fat composition according to the invention comprises, relative to the total weight of the fat composition: 70 to 95% by weight, preferably 75 to 90% by weight, of base oil(s) including at least one ester oil, 3 to 20% by weight, preferably 4 to 15% by weight of thickener(s) selected from lithium salts and fatty acid possibly hydroxylated comprising 10 to 28 carbon atoms, 0.5 to 10% by weight, preferably 1 to 5% by weight of calcium carbonate, 1 to 15% by weight, preferably 2 to 10% by weight, of at least one additive selected from extreme-pressure additives.

[0101] According to one embodiment, the fat composition according to the invention comprises, relative to the total weight of the fat composition: 70 to 95% by weight, preferably 75 to 90% by weight, of base oil(s) including at least one ester oil, 3 to 20% by weight, preferably 4 to 15% by weight of thickener(s) selected from lithium salts and fatty acid possibly hydroxylated comprising 10 to 28 carbon atoms, 0.5 to 10% by weight, preferably 1 to 5% by weight of calcium carbonate, 1 to 15% by weight, preferably 2 to 10% by weight, of at least one additive selected from extreme-pressure additives selected from sulfur fatty acid esters, sulfur olefins and mixtures thereof.

[0102] According to one embodiment, the fat composition according to the invention comprises, relative to the total weight of the fat composition: 70 to 95% by weight, preferably 75 to 90% by weight, of base oil(s) including at least one ester oil, 3 to 20% by weight, preferably 4 to 15% by weight of thickener(s) selected from lithium salts and fatty acid possibly hydroxylated comprising 10 to 28 carbon atoms, 0.5 to 10% by weight, preferably 1 to 5% by weight of calcium carbonate having a D50 particle size of 5 to 10 µm and a D90 particle size of 10 to 30 µm, 1 to 15% by weight, preferably 2 to 10% by weight, of at least one additive selected from extreme-pressure additives.

[0103] According to one embodiment, the fat composition according to the invention comprises, relative to the total weight of the fat composition: 70 to 95% by weight, preferably 75 to 90% by weight, of base oil(s) including at least one ester oil, 3 to 20% by weight, preferably 4 to 15% by weight of lithium 12-hydroxystearate thickener, 0.5 to 10% by weight, preferably 1 to 5% by weight of calcium carbonate having a D50 particle size of 3 to 20 µm and a D90 particle size of 10 to 50 µm, 1 to 15% by weight, preferably 2 to 10% by weight, of at least one additive selected from the extreme-pressure additives.

[0104] According to one embodiment, the fat composition according to the invention comprises, relative to the total weight of the fat composition: 70 to 95% by weight, preferably 75 to 90% by weight, of base oil(s) including at least one ester oil, 3 to 20% by weight, preferably 4 to 15% by weight of lithium 12-hydroxystearate thickener, 0.5 to 10% by weight, preferably 1 to 5% by weight of calcium carbonate having a D50 particle size of 4 to 15 µm and a D90 particle size of 10 to 40 µm, 1 to 15% by weight, preferably 2 to 10% by weight, of at least one additive selected from the extreme-pressure additives.

[0105] According to one embodiment, the fat composition according to the invention comprises, relative to the total weight of the fat composition: 70 to 95% by weight, preferably 75 to 90% by weight, of base oil(s) including at least one ester oil, 3 to 20% by weight, preferably 4 to 15% by weight of lithium 12-hydroxystearate thickener, 0.5 to 10% by weight, preferably 1 to 5% by weight of calcium carbonate having a D50 particle size of 4 to 15 µm and a D90 particle size of 10 to 40 µm, 1 to 15% by weight, preferably 2 to 10% by weight, of at least one additive selected from among the extreme-pressure additives chosen from among sulfur-containing fatty acid esters, sulfur-containing olefins and mixtures thereof.

[0106] The grease composition according to the invention preferably has a viscosity at 40°C greater than or equal to 100 cSt, preferably even greater than or equal to 200 cSt, preferably even greater than or equal to 300 cSt, preferably even greater than or equal to 400 cSt, preferably even greater than or equal to 500 cSt.

[0107] Viscosity is preferably measured according to ASTM D445.

[0108] The fat composition according to the invention preferably has a carbon content of biological origin greater than or equal to 40% by weight, preferably at least 45% by weight, relative to the total weight of carbon atoms in the fat composition.

[0109] The biologically sourced carbon content, also known as biogenic carbon content, can be determined according to the ASTM D6866 method.

[0110] The grease composition according to the invention can be prepared by any process known to those skilled in the art for preparing grease. Preferably, a preformed thickener is used in the preparation process. Typically, the grease preparation process includes a step of contacting the calcium carbonate thickener with the base oil and a step of heating until the soap melts (and the grease is formed). If additives are present, they can be added before or after cooling. After cooling, the grease composition is generally homogenized by grinding.

[0111] The invention also relates to the use of the grease composition in off-road (in French "non-routier"), agricultural, wind-powered machines, such as "off-road" vehicles, construction equipment, agricultural machinery and wind turbines.

[0112] Typically, the grease composition according to the invention is used to lubricate at least one component of an off-road, agricultural or wind turbine, preferably chosen from construction equipment, agricultural machinery and wind turbines.

[0113] The invention also relates to a method of lubricating at least one component of an off-road, agricultural or wind-powered machine, preferably chosen from construction equipment, agricultural machinery and wind turbines, said method comprising bringing the component into contact with a grease according to the invention.

[0114] More specifically, the grease according to the invention can be used in bearings (ball, roller, needle), rolling and sliding bearings, open gears, wire ropes and chain drives, and more generally in applications not involving a sealing system.

[0115] All the characteristics and preferences presented for the grease according to the invention apply to the lubrication process of the component of an off-road vehicle according to the invention.

[0116] The invention will now be described by means of the following examples, given of course by way of illustration and not limitation of the invention. Examples Example 1: Preparation of fat compositions

[0117] The fats were prepared according to the following protocol: The fats used in the examples are prepared as follows: the thickener and calcium carbonate are placed in their base oil and heated until the soap melts. After cooling, the additives are then added in different proportions and the fat composition is homogenized with a grinder.

[0118] The fat compositions prepared and tested are detailed in Table 1 where the proportions are proportions expressed by weight, relative to the total weight of the fat composition. [Table 1] CC1 CC2 CC3 CI4 Base oil(s) 84,60% 85,40% 84,70% 84,70% Thickening 7,30% 8,90% 8,00% 8,00% CaCO3 (1) 2,50% 3,00% CaCO3 (2) 3,00% Wear-resistant 1,50% 1,50% Additive pack 4,10% 4,10% 4,30% 4,30%

[0119] The base oil(s) comprise a mixture of two ester-type oils. The base oil(s) have a biodegradability of 70% and 75%, measured according to OECD 301B at 28 days. The thickener is lithium 12-hydroxystearate, which has a biodegradability of 97% at 28 days.

[0120] CaCO3 (1) is a calcium carbonate with a D50 particle size of 2.14 µm and a D90 particle size of 8.04 µm.

[0121] CaCO3(2) is a calcium carbonate with a D50 particle size of 7.08 µm and a D90 particle size of 14.9 µm.

[0122] The anti-wear agent is an anti-wear agent comprising a mixture of phosphate amines.

[0123] The additive package includes an extreme pressure sulfur ester type additive, an antioxidant additive and a metal passivating additive.

[0124] Composition CI4 according to the invention exhibits a 28-day biodegradability of 67.26%, calculated from the biodegradabilities of the base oils and the thickener.

[0125] The particle size of the calcium carbonate used in the examples was measured by a laser diffraction method well known to those skilled in the art.

[0126] In this example, a Malvern Mastersizer Hydro R diffractometer was used.

[0127] If macroscopic agglomerates are present (e.g. sizes greater than 400 µm) then mechanical sieving can be implemented with two different sieves (400 µm and 800 µm) in order to reduce the macroscopic agglomerates.

[0128] If macroscopic agglomerates remain after mechanical sieving, drying the sample at 100°C can be implemented to further reduce the amount of macroscopic agglomerates.

[0129] For the analysis of the results, it is possible to disregard the proportion of macroscopic agglomerates, using a cross-section at, for example, 100 µm, 50 µm, or 25 µm (depending on the agglomerate size). The cross-section has no significant impact on the D50 or D90 particle size measurement of the calcium carbonate used in the examples.

[0130] Example 2: Determination of anti-wear and extreme-pressure properties The anti-wear and extreme-pressure (EP) properties of the grease compositions detailed in Table 1 were determined and the results are shown in Table 2. [Table 2] Standard CC1 CC2 CC3 CI4 Anti-wear 4-ball 60 min 40 kgf ASTM D-2266 0.67 mm 0.62 mm 0.65 mm 0.54 mm EP 4-ball (welding charge) ASTM D-2596 620 kgf 500 kgf 620 kgf 620 kgf EP 4-ball (charge wear index) ASTM D-2596 91,4 76 97,1 108,7

[0131] The results in Table 2 show that the grease composition according to the invention CI4 exhibits better anti-wear and extreme-pressure properties than the grease compositions CC1, CC2 and CC3.

[0132] Although the CI4 grease composition does not include anti-wear, it exhibits better anti-wear properties than the CC1 and CC2 grease compositions which include an anti-wear additive.

[0133] The CI4 grease composition includes a calcium carbonate with the claimed particle size which exhibits better anti-wear properties than the CC3 composition which includes a calcium carbonate with a different particle size. Example 3: Determining adhesive power

[0134] Compositions CC1 and CI4 were tested for their stickiness by a water spray off test.

[0135] The viscosity at 40°C of the compositions is 680 cSt, measured according to ASTM D445.

[0136] The adhesive strength is shown in Table 3. [Table 3] Standard CC1 CI4 Water loss per spray at 40 psi and 38°C ASTM D4049 - ISO 110009 22% 10,4%

[0137] The results in Table 3 show that composition CI4 has very good adhesive properties. The grease composition according to the invention is therefore particularly well-suited to the components of off-road vehicles with low rotational speeds.

Claims

1. A grease composition comprising, relative to the total weight of the grease composition: a) from 70 to 95% by weight of base oil(s) each having a 28-day biodegradability of at least 60% as measured according to standard OECD 301B; b) from 1 to 20% by weight of thickener(s) chosen from among fatty acid metal salts, each thickener having a 28-day biodegradability of at least 60% as measured according to standard OECD 301B; c) from 0.5 to 10% by weight of calcium carbonate having a D50 particle size greater than or equal to 3 µm and a D90 particle size greater than or equal to 10 µm.

2. The composition according to claim 1 comprising, relative to the total weight of the grease composition: a) from 70 to 95% by weight of base oil(s) each having a 28-day biodegradability of at least 60% as measured according to standard OECD 301B; b) from 2 to 20% by weight of thickener(s) chosen from among fatty acid metal salts, each thickener having a 28-day biodegradability of at least 60% as measured according to standard OECD 301B; c) from 0.5 to 10% by weight of calcium carbonate having a D50 particle size greater than or equal to 3 µm and a D90 particle size greater than or equal to 10 µm.

3. The composition according to claim 1 or 2, characterized in that it has a 28-day biodegradability of at least 60%, calculated from the 28-day biodegradability of the base oil(s) and thickener(s), the 28-day biodegradability of the base oil(s) and thickener(s) being measured following the method of OECD 301B.

4. The composition according to one of claims 1 to 3, wherein the thickener is chosen from among optionally hydroxylated lithium salts of fatty acids, optionally hydroxylated calcium salts of fatty acids and the mixtures thereof, preferably from optionally hydroxylated lithium salts of fatty acids, preferably lithium 12-hydroxystearate.

5. The composition according to one of claims 1 to 4, wherein the base oils are chosen from among ester oils.

6. The composition according to one of claims 1 to 5, wherein the calcium carbonate has a D50 particle size ranging from 3 to 20 µm and a D90 particle size ranging from 10 to 50 µm.

7. The composition according to any of claims 1 to 6, further comprising at least one extreme-pressure additive, preferably in an amount ranging from 1 to 15% by weight relative to the total weight of the composition.

8. The composition according to any of claims 1 to 7, said composition being free of antiwear additive of amine phosphate type, of zinc diamyldithiocarbamate type and of zinc dialkyl dithiophosphate type.

9. The composition according to any of claims 1 to 8, comprising at least 40% by weight of carbon of biological origin, preferably at least 45% by weight of carbon of biological origin, relative to the total weight of the carbon atoms of the composition.

10. Use of the grease composition according to any of claims 1 to 9, in an off-road, agricultural or wind energy device.

11. The use according to claim 10, wherein the off-road, agricultural or wind energy device is chosen from among construction equipment, agricultural machinery, and wind turbines.