SOLID LUBRICANT COMPOSITION AND ITS USE, METHOD FOR LUBRICATING A CHAIN

Description

FIELD OF THE INVENTION

[0001] The present invention relates to a solid lubricant composition, a method for lubricating a chain and the use of the solid lubricant composition for lubrication. BACKGROUND

[0002] In many technical applications, lubricants are used primarily to reduce friction and wear. Depending on the consistency and physical state of the lubricant, a distinction is made between liquid lubricants (such as lubricating oils), lubricating greases, solid lubricants, and gaseous lubricants.

[0003] Solid lubricants, which can also be referred to as dry lubricants, typically contain particles or platelets that slide easily against each other and can therefore reduce friction. Solid lubricants can be used in particular when you want to lubricate components, but a) there is a dusty ambient condition; b) oil-like lubricants can easily be thrown off (for example, when lubricating chains); c) you want to prevent heavy soiling of clothing upon contact; d) you absolutely want to prevent the lubricant from dripping; e) you cannot easily work with bonded coatings because you have many moving parts in lubricating contact.

[0004] Conventional solid lubricants, which can also be used as chain lubricants, are usually based on waxes and contain black solid lubricants (e.g. MoS 2 / graphite); PTFE; hexagonal boron nitride (BN); layered silicates (e.g. ceramic solid lubricants); inorganic salts containing heavy metals (e.g. molybdenum dithiocarbamate (MoDTC)) or cerium trifluoride (CeF 3 )) or polymers such as polyethylene or polypropylene.

[0005] However, waxes can only be used within a limited temperature range. Commonly used waxes are, for example, Alox 2213C or D. These are based on oxidized paraffin waxes in which the carboxylic acid functionalities formed by oxidation have been neutralized with alkaline earth hydroxides / oxides. For dry chain lubrication at room temperature, waxes with a melting point of around 40 - 50 °C are often used. At low temperatures (e.g., not uncommon down to -20 °C in bicycle chain lubrication), these waxes are extremely hard and have poor lubricating properties or can even restrict the mobility of the chain links. At high temperatures (sunlight; mechanical stress (e.g., motorcycle chains)), the waxes melt and lose their consistency - there is a risk of dripping or, in the case of rapid movements, slinging off of the lubricant.

[0006] However, the solid lubricants used also have disadvantages: black solid lubricants such as MoS 2 or graphite have a high contamination potential, PTFE is problematic with regard to microplastics and per- and polyfluorinated alkyl substances (PFAS); hexagonal boron nitride is very expensive; layered silicates have poorer performance, inorganic salts containing heavy metals contain heavy metals and are usually not white, and polymers such as polyethylene or polypropylene are also problematic with regard to microplastics.

[0007] Microplastics are becoming an increasingly serious environmental problem due to their generally poor biodegradability. Microplastics also accumulate in the human body via the food chain, leading to health problems that are not yet fully understood.

[0008] Fluorinated polymers are particularly critical because they are extremely difficult to degrade. Chain lubrication usually leads to lubricant losses. In the case of motorcycle and bicycle chains, this inevitably means a certain amount of release into the environment.

[0009] Lubricating grease compositions are known from the prior art, as described, among others, in EP 2 824 166 B1, US 2011 / 0306527 A1, WO 2021 / 155968 A1, EP 3 959 296 B1, EP 2 891 702 A1, and DE 11 2017 001 618 T5. PTFE or boron nitride are typically used as solid lubricants.

[0010] US 5 898 022 A discloses a multifunctional light lubricant comprising an insoluble particulate chemical bond weakener containing one or more of talc, graphite, polytetrafluoroethylene, solid fluorinated hydrocarbons, and boron nitride in a range of about 5 to about 25 percent of the total weight, in suspension in a solution of a soluble wax having a melting point between about 41°C and about 85°C in a range of about 6 to about 35 percent of the total weight, an oil component in a percentage of the total weight that is less than the percentage of the total weight of the soluble wax, wherein the oil component comprises a hydrocarbon oil, silicone oil, vegetable oil, animal oil, or a fat derived therefrom; and a volatile solvent in a range of about 35 to about 90 percent of the total weight.

[0011] There may therefore be a need for a solid lubricant composition that can reduce or ideally overcome the disadvantages described above. OBJECT OF THE INVENTION

[0012] An object of the present invention is therefore to provide a solid lubricant composition which is particularly suitable for the lubrication of chains and can be applied particularly well and precisely, which is white and which is essentially free of microplastics and PFAS and nevertheless has a similarly good performance as existing PTFE-based solid lubricant compositions. SUMMARY OF THE INVENTION

[0013] The inventors of the present invention have conducted extensive studies to solve this problem and, in particular, discovered that by combining at least three light-colored solids—a fatty acid amide, a dicarboxylic acid, or a salt thereof, and boron nitride—a replacement for a PTFE-based solid lubricant composition can be provided that not only enables similarly good properties to those achieved with PTFE, but surprisingly exhibits far better lubrication performance that lasts much longer. In addition, very good corrosion protection can be achieved. Combined with a lubricating grease base and a solvent or propellant, a solid lubricant composition obtained in this way can be applied particularly effectively and precisely, for example, to a chain.

[0014] The present invention accordingly relates to a solid lubricant composition (dry lubricant composition) comprising a solid lubricant mixture comprising or consisting of a fatty acid amide, a dicarboxylic acid or a salt thereof, and boron nitride. The solid lubricant composition further comprises a grease base and a solvent and / or a propellant.

[0015] Furthermore, the present invention relates to a method for lubricating a chain, the method comprising providing a solid lubricant composition as described herein and applying the solid lubricant composition to a chain.

[0016] Furthermore, the present invention relates to the use of a solid lubricant composition as described herein for lubrication, in particular for lubrication of a chain.

[0017] Further objects and advantages of embodiments of the present invention will become apparent from the following detailed description and the accompanying drawings. BRIEF DESCRIPTION OF THE ILLUSTRATIONS

[0018] Figure 1 is a photographic representation of the chain test bench AU01, which was used to determine the power loss of the solid lubricant composition. Figure 2 is a schematic representation of a chain drive. Figure 3 is a photographic representation of the chain drive as it is used in the Figure 1 The chain test bench AU01 shown is used. Figure 4 is a graph showing the power loss as a function of time on the chain test bench for two exemplary embodiments of the present application. Figure 5is a graph showing power loss versus time on the chain test bench for an exemplary embodiment of the present application and two competitor products. Figure 6 is a graph showing power loss versus time on the chain test bench for an exemplary embodiment of the present application and a PTFE-containing competitor product. Figure 7 is a photographic representation of test panels treated with a solid lubricant composition according to exemplary embodiments of the present application or with competitor products, after a salt spray test according to DIN EN ISO 9227. DETAILED DESCRIPTION OF THE INVENTION

[0019] Further details of the present invention and further embodiments thereof are described below. However, the present invention is not limited to the following detailed description, but is merely illustrative of the teachings of the invention.

[0020] It should be noted that features described in connection with one exemplary embodiment can be combined with any other exemplary embodiment. In particular, features described in connection with an exemplary embodiment of a solid lubricant composition according to the invention can be combined with any other exemplary embodiment of a solid lubricant composition according to the invention, as well as with any exemplary embodiment of a method according to the invention, and with any exemplary embodiment of a use according to the invention, and vice versa, unless expressly stated otherwise.

[0021] When a term is referred to with an indefinite or definite article, such as "a," "an," "one," "the," "the," and "the," in the singular, this includes the plural term, and vice versa, unless the context clearly indicates otherwise. The terms "comprising" and "include," as used herein, include not only the meaning of "containing" or "include," but can also mean "consisting of" and "consist essentially of."

[0022] In a first aspect, the present invention relates to a solid lubricant composition which is particularly suitable for the lubrication of chains.

[0023] The term "solid lubricant composition" as used herein can mean, in particular, that the lubricant composition, after application to the object to be lubricated, forms a dry-feeling lubricant film, meaning that any solvent largely evaporates or any propellant largely dissipates. Accordingly, the solid lubricant composition can also be referred to as a dry lubricant composition.

[0024] The solid lubricant composition comprises (or consists of) a solid lubricant mixture, a lubricating grease base, and a solvent and / or a propellant. The solid lubricant mixture, in turn, comprises (or consists of) a fatty acid amide, a dicarboxylic acid or a salt thereof, and boron nitride. Of course, several of the individual components can also be included, for example, two or more fatty acid amides, two or more dicarboxylic acids or salts thereof, or one or more dicarboxylic acids and one or more salts thereof.

[0025] According to an exemplary embodiment, the fatty acid amide comprises an amide or diamide of a saturated or unsaturated, aliphatic or aromatic, linear or branched, substituted or unsubstituted fatty acid having 8 to 30 carbon atoms, optionally containing one or more hydroxyl groups. The fatty acid may in particular have 10 to 28 carbon atoms, in particular 12 to 26 carbon atoms, in particular 16 to 24 carbon atoms. The meaning of the terms "saturated," "unsaturated," "aliphatic," "aromatic," "linear," "branched," and "unsubstituted" as used herein corresponds to the respective established meanings thereof, as known to a person skilled in the art. The term "substituted" as used herein means that one or more, in particular 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10 hydrogen atoms of the respective groups are substituted by a substituent.Examples of suitable substituents include hydroxyl groups, hydroxyalkyl groups (ethers), thiol groups, thioalkyl groups (thioethers), =O, ester groups, amide groups, nitrile groups, and nitro groups, especially one or more hydroxyl groups. When two or more substituents are present, they may be the same or different and may be linked together to form a ring.

[0026] According to an exemplary embodiment, the fatty acid amide comprises at least one selected from the group consisting of stearic acid amide (stearamide), oleic acid amide (oleamide), palmitic acid amide (palmitamide), erucic acid amide (erucamide), ricinoleic acid amide, distearylethylenediamide (stearylstearic diamide), dioleylethylenediamide (oleamidoleic diamide), dipalmitylethylenediamide (palmitamide palmitic diamide), and combinations thereof. Of these, stearic acid amide has proven particularly suitable for achieving the object of the invention.

[0027] According to an exemplary embodiment, the solid lubricant mixture comprises 1 to 80 wt.%, in particular 5 to 50 wt.%, in particular 10 to 40 wt.%, of one or more fatty acid amides.

[0028] According to an exemplary embodiment, the dicarboxylic acid comprises a saturated or unsaturated, aliphatic or aromatic, linear or branched, substituted or unsubstituted dicarboxylic acid having 2 to 20 carbon atoms. The dicarboxylic acid may in particular have 4 to 16 carbon atoms, in particular 6 to 12 carbon atoms, in particular 8 to 10 carbon atoms.

[0029] According to an exemplary embodiment, the solid lubricant mixture comprises a salt of the dicarboxylic acid. In particular, this can be a disodium salt, a dipotassium salt, a dicalcium salt, a diammonium salt, a monosodium salt, a monopotassium salt, a monocalcium salt, a monoammonium salt, or a combination thereof. For example, the solid lubricant mixture can be a disodium salt of a dicarboxylic acid and a monosodium salt of the same or a different dicarboxylic acid. Combinations of different cations are also possible. A sodium salt, in particular a disodium salt, of a dicarboxylic acid has proven particularly advantageous for achieving the object of the invention.

[0030] According to an exemplary embodiment, the solid lubricant mixture comprises 10 to 95 wt.%, in particular 30 to 90 wt.%, in particular 40 to 85 wt.%, of one or more dicarboxylic acids or salts thereof.

[0031] According to an exemplary embodiment, the boron nitride is a boron nitride with a hexagonal crystal structure. This allows for particularly good lubricating properties.

[0032] According to an exemplary embodiment, the solid lubricant mixture comprises 1 to 20 wt.%, in particular 2 to 15 wt.%, in particular 3 to 10 wt.%, boron nitride.

[0033] According to an exemplary embodiment, the weight ratio of fatty acid amide, dicarboxylic acid or salt thereof and boron nitride is as follows: Fettsäureamid : Dicarbonsäure / Salz : Bornitrid = 5 - 15 : 70 - 92 : 3 - 15

[0034] According to an exemplary embodiment, the fatty acid amide and boron nitride are present in a weight ratio of 6:1 to 2:1, in particular 5:1 to 3:1, in particular approximately 4:1.

[0035] According to an exemplary embodiment, the solid lubricant composition comprises 5 to 20 wt.%, in particular 7 to 15 wt.%, in particular 8 to 12 wt.%, of the solid lubricant mixture.

[0036] In addition to the solid lubricant mixture, the solid lubricant composition also comprises a lubricating grease base as well as a solvent and / or a propellant.

[0037] According to an exemplary embodiment, the lubricating grease base comprises a soap-based grease. This can be, in particular, a fatty acid salt, particularly a calcium sulfonate complex grease. A calcium sulfonate complex grease is characterized by a particularly wide temperature range, especially in the low-temperature range.

[0038] According to an exemplary embodiment, the solid lubricant composition comprises 10 to 40 wt.%, in particular 15 to 30 wt.%, in particular 20 to 25 wt.%, of the lubricating grease base.

[0039] According to an exemplary embodiment, the weight ratio of solid lubricant mixture and lubricating grease base is in the range of 1:5 to 5:1, in particular in the range of 1:3 to 1:1, in particular approximately 1:2.

[0040] According to an exemplary embodiment, the solid lubricant composition contains a solvent. In the context of the present application, a "solvent" is understood to mean, in particular, a chemical compound capable of dissolving or at least partially dissolving other substances, in particular the components described above.

[0041] According to an exemplary embodiment, the solvent comprises a hydrocarbon. Combinations of several hydrocarbons or of one or more hydrocarbons and another solvent are also possible. Preferably, the solvent is a halogen-free solvent, in particular a halogen-free hydrocarbon.

[0042] According to an exemplary embodiment, it is advantageous if the solvent has a high vapor pressure or a low boiling point, for example, a boiling point at 101.3 kPa of less than 80°C, in particular less than 60°C. This advantageously allows rapid and essentially complete evaporation of the solvent after application of the solid lubricant composition to the component to be lubricated, forming a dry-feeling lubricant film.

[0043] According to an exemplary embodiment, the solid lubricant composition contains a propellant. In this case, the solid lubricant composition can also be referred to as a solid lubricant aerosol formulation. In the context of the present application, a "propellant" is understood in particular to mean a liquid or gaseous substance that is typically liquefied or compressed under pressure and is capable of conveying and possibly atomizing other substances, in particular liquids or solids, through its pressure.

[0044] According to an exemplary embodiment, the propellant comprises a liquefied gas, in particular propane and / or butane. It is preferably a halogen-free propellant, in particular a halogen-free liquefied gas. The propellant may also additionally contain a solvent, in particular a solvent as described above.

[0045] According to an exemplary embodiment, the solid lubricant composition comprises 30 to 90 wt.%, in particular 50 to 80 wt.%, in particular 60 to 70 wt.%, of the solvent and / or the propellant.

[0046] According to an exemplary embodiment, the solid lubricant composition is essentially free of plastic, in particular microplastics, and / or per- and polyfluorinated alkyl substances (PFAS). Within the context of the present application, "essentially free" means that plastic, in particular microplastics, and / or PFAS, are contained at most in technically unavoidable amounts (due to the ubiquity of these substances), and in particular, no plastic, in particular microplastics, and / or PFAS, nor any starting materials therefor, are intentionally added to the solid lubricant composition.

[0047] The preparation of the solid lubricant composition is not subject to any particular restrictions or specifications and can be carried out by a person skilled in the art using the described components in a conventional manner. Advantageously, the solid components are converted into liquid form by heating (where possible) to facilitate thorough mixing.

[0048] The solid lubricant composition can be filled and packaged in a suitable container, for example a bottle or a can, in particular a dropper bottle, a spray bottle, a spray can or an aerosol can, and thus made available for use.

[0049] In another aspect, the present invention relates to a method for lubricating a chain, the method comprising providing a solid lubricant composition as described herein and applying the solid lubricant composition to a chain.

[0050] The application of the solid lubricant composition to the chain can be carried out in particular by dripping or spraying the solid lubricant composition directly onto the chain.

[0051] According to an exemplary embodiment, the chain is a part of a means of transport, in particular a two-wheeler, in particular a bicycle or a motorcycle.

[0052] In a further aspect, the present invention relates to the use of a solid lubricant composition as described herein for lubrication, in particular for lubricating a chain. According to an exemplary embodiment, the chain is a part of a means of transport, in particular a two-wheeled vehicle, in particular a bicycle or a motorcycle.

[0053] The present invention is further described with reference to the following examples, which are merely intended to illustrate the teachings of the invention and are not intended to limit the scope of the present invention in any way. Examples

[0054] In the following, experimental data of embodiments of an exemplary solid lubricant composition according to the invention and of competitive products are described. For the samples examined, the power loss of the solid lubricant composition was determined on the chain test bench AU01 and the corrosion protection behavior in the salt spray test according to DIN EN ISO 9227. Samples examined:

[0055] Solid lubricant composition according to the invention: Solid lubricant mixture: 12% of a monounsaturated fatty acid amide (C16-C24), 84% of a disodium salt of a short-chain dicarboxylic acid, 3% hexagonal boron nitride; soap grease from the class of calcium sulfonate complex greases as the lubricating grease base; embodiment 1A) with solvent; embodiment 1B) with propellant as an aerosol; Competitor product A: wax with ceramic solid lubricants; Competitor product B: molten wax with solids. Components: paraffin, MoS 2 and WS 2 (tungsten disulfide); Competitor product C: PTFE oil; Competitor product D: dry lubricant (no further description); Competitor product E: PTFE oil; Competitor product F: dry lubricant with PTFE; Competitor product G: wax with PTFE and ceramic solids. Test method chain test bench:

[0056] Figure 1is a photographic representation of the chain test bench AU01, which was used to determine the power loss of the solid lubricant composition.

[0057] Using the chain test bench, the influence of a chain lubricant on the power loss of the entire drive can be determined. The measured values ​​and their changes over time allow conclusions to be drawn about the durability, quality, and friction reduction of the lubricating film.

[0058] To determine the power loss, a test run with defined measuring and load conditions is carried out over 20 hours. During the tests, the speed and torque are measured at the input (crank) and the output (pinion) (see Figure 2 ) . The effectiveness of the chain drive is assessed from the efficiency and power loss curves.

[0059] The test field is conditioned to a constant temperature of 22°C. The torque sensors deliver four signals per revolution, and the deviation and repeatability accuracy is 0.03%.

[0060] Figure 3 is a photographic representation of the chain drive as it is in the Figure 1 The chain test bench AU01 shown is used. Results on the chain test bench

[0061] 1. Test run of a typical embodiment of the dry chain lubricant 1) according to the invention in various application forms: In the Figure 4The diagram shown shows the dry chain lubricant 1) according to the invention twice - once as a liquid product in a dropper bottle 1B) and once as an aerosol 1A). In both test runs, the difference between the starting value and the final value is small, from which it can be concluded that the lubricating film is intact until the end of the test run. The power loss of 5.2 and 5.9 watts, respectively, is surprisingly extremely low for a dry chain lubricant and has never been found in this order of magnitude in a competitor's product. 2. Comparison between a typical embodiment of the invention 1) and typical very good competitor products: In the Figure 5The diagram shows the exemplary embodiment 1B) according to the invention and two competitive products that exhibit a typical dry chain lubricant loss. Most lubricants in this category have an averagely good initial value, but gradually the lubricant is lost in the chain drive until the lubricant film is completely destroyed (competitive product B). Competitive product A) lasts until the end on the chain test bench, but has a very high average power loss, which leads to high wear on the materials and inefficiency of the drive. 3. Comparison with PTFE-containing lubricants: In the Figure 6 The diagram shown shows the exemplary embodiment 1B) according to the invention in comparison with an oil containing large amounts of PTFE.

[0062] Due to their lower internal friction, oils tend to have lower friction values ​​and long-term stable lubricating films compared to dry chain lubricants - but in this case, even larger amounts of PTFE do not help to generate similarly good power losses.

[0063] In addition to the disadvantage that PTFE is considered a microplastic and must be classified as a PFAS, its performance in terms of reducing the coefficient of friction can be significantly exceeded by the exemplary embodiment according to the invention. Corrosion protection behavior in the salt spray test according to DIN EN ISO 9227:

[0064] Another required property of dry chain lubricants is their corrosion protection. To simulate adverse environmental influences, the salt spray test according to DIN EN ISO 9227 was chosen. Figure 7The test panels can be seen after a test duration of 24 hours. Fortunately, the dry lubricant according to the exemplary embodiments 1A) and 1B) according to the invention has a very positive effect on the corrosion protection of the entire system. Competitors D) to G) failed this test.

[0065] The present invention has been described using specific embodiments and examples. However, the invention is not limited thereto, and various modifications are possible without departing from the scope of the present invention.

Claims

1. A solid lubricant composition comprising a solid lubricant mixture comprising a fatty acid amide, a dicarboxylic acid or a salt thereof, and boron nitride; a lubricating grease base; a solvent and / or a blowing agent.

2. The solid lubricant composition according to claim 1, wherein the fatty acid amide comprises an amide or diamide of a saturated or unsaturated, aliphatic or aromatic, linear or branched, substituted or unsubstituted fatty acid having 8 to 30 carbon atoms, optionally comprising one or multiple hydroxyl groups.

3. The solid lubricant composition according to claim 1 or 2, wherein the fatty acid amide is selected from the group consisting of stearic acid amide, oleic acid amide, palmitic acid amide, erucic acid amide, ricinoleic acid amide, distearyl ethylene diamide, dioleyl ethylene diamide, dipalmityl ethylene diamide, and combinations thereof.

4. The solid lubricant composition according to any of the preceding claims, wherein the dicarboxylic acid comprises a saturated or unsaturated, aliphatic or aromatic, linear or branched, substituted or unsubstituted dicarboxylic acid having 2 to 20 carbon atoms.

5. The solid lubricant composition according to any of the preceding claims, wherein the solid lubricant mixture comprises a salt of the dicarboxylic acid, in particular selected from the group consisting of a disodium salt, a dipotassium salt, a dicalcium salt, a diammonium salt, a monosodium salt, a monopotassium salt, a monocalcium salt, and a monoammonium salt.

6. The solid lubricant composition according to any of the preceding claims, wherein the boron nitride is a hexagonal crystal structure boron nitride.

7. The solid lubricant composition according to any of the preceding claims, wherein the solid lubricant mixture comprises: 1 to 80 wt%, in particular 5 to 50 wt%, in particular 10 to 40 wt%, of the fatty acid amide, 10 to 95 wt%, in particular 30 to 90 wt%, in particular 40 to 85 wt%, of the dicarboxylic acid or the salt thereof, 1 to 20 wt%, in particular 2 to 15 wt%, in particular 3 to 10 wt%, of boron nitride.

8. The solid lubricant composition according to any of the preceding claims, wherein the weight ratio of fatty acid amide, dicarboxylic acid or salt thereof, and boron nitride is as follows:

9. The solid lubricant composition according to any of the preceding claims, wherein at least one of the following features (A) to (E) is fulfilled: (A) wherein the fatty acid amide and boron nitride are contained in the weight ratio of 6:1 to 2:1; (B) wherein the lubricating grease base comprises a soap grease, in particular a fatty acid salt, in particular a calcium sulfonate complex grease; (C) wherein the solid lubricant composition contains a solvent, in particular a hydrocarbon; (D) wherein the solid lubricant composition contains a blowing agent, wherein the blowing agent comprises a liquefied gas, in particular propane and / or butane; (E) wherein the weight ratio of solid lubricant mixture and lubricating grease base is in the range of 1:5 to 5:1, in particular in the range of 1:3 to 1:1, in particular about 1:2.

10. The solid lubricant composition according to any of the preceding claims, comprising 5 to 20 wt.-%, in particular 7 to 15 wt.-%, in particular 8 to 12 wt.-%, of the solid lubricant mixture, 10 to 40 wt.-%, in particular 15 to 30 wt.-%, in particular 20 to 25 wt.-%, of the lubricating grease base, 30 to 90 wt.-%, in particular 50 to 80 wt.-%, in particular 60 to 70 wt.-%, of the solvent and / or the blowing agent.

11. The solid lubricant composition according to any of the preceding claims, wherein the solid lubricant composition is substantially free of plastic, in particular microplastic, and / or per- and polyfluorinated alkyl substances (PFAS).

12. A method for lubricating a chain comprising providing a solid lubricant composition according to any of claims 1 to 11; applying the solid lubricant composition to a chain.

13. The method according to claim 12, wherein the chain is part of a means of transportation, in particular a two-wheeled vehicle, in particular a bicycle or a motorcycle.

14. Use of a solid lubricant composition according to any of claims 1 to 11 for lubricating.

15. The use according to claim 14 for lubricating a chain, in particular the chain of a means of transportation, in particular a two-wheeled vehicle, in particular a bicycle or a motorcycle.