Lubricant composition, lubricating film and lubricant concentrate for screws

Abstract

The invention relates to a lubricant composition in the form of a dispersion for coating screws with a lubricating film, a lubricating film, and a lubricant concentrate. The lubricant composition or the lubricating film comprises a combination of at least two different waxes and microspherical inorganic particles. The lubricant composition is used for coating screws and provides screws coated with a lubricating film that exhibit coefficients of friction within a defined range when tightened against multiple materials.

Description

[0001] The present invention relates to a lubricant composition in the form of a dispersion for coating screws with a lubricating film and to the lubricating film itself. According to the invention, the lubricant composition can also be provided as a lubricant concentrate that can be further diluted with water. The lubricant composition or the lubricating film comprises a combination of at least two different waxes and microspherical inorganic particles. The lubricant composition is used for coating screws and provides screws coated with a lubricating film that exhibit coefficients of friction within a defined range when repeatedly tightened against different materials. Introduction and state of the art

[0002] The function of lubricants on screws is to achieve defined coefficients of friction with low variation, enabling the screw to be used as a mechanical component in a structure with a predetermined preload. Lubricants with and without binders can be used to achieve these defined coefficients of friction. Commonly used friction-adjusting components include polymers, waxes, and / or solid lubricants such as PTFE or molybdenum disulfide (MoS2).

[0003] Screws can be fastened to various material surfaces, such as aluminum, steel, or e-coatings. In cathodic dip coating (e-coating), also known as cathodic electrophoretic deposition (EPD), the component is immersed in an aqueous, electrically conductive coating. Applying an electric field causes the coating to be deposited evenly, and it is then baked at approximately 200 °C. The result is a continuous, uniform organic coating layer with thicknesses between 15 and 45 µm.

[0004] WO 2010 / 077773 A1 describes lubricants containing surface-modified inorganic spheroidal nanoparticles for reducing the coefficient of friction.

[0005] German patent DE 102014119567 A1 discloses a lubricant for use on the sliding surfaces of winter sports equipment, containing spherical particles as solid or hollow spheres with a mean diameter of less than 50 µm in combination with film-forming agents such as greases, waxes, resins, or oils. The lubricant forms a film that remains on the winter sports equipment for an extended period of time.

[0006] US10087334 B2 describes the use of microspheres in floor coatings as an anti-slip additive.

[0007] EP 2540781 A1 discloses the coating of nails, nail screws, and bolts with coating compositions containing polymeric binders, solvents, and particulate, layered, or fibrous fillers made of various materials, such as silica, pyrogenic silica or precipitated silica, foamed glass particles, sand, clay, chalk, gypsum, talc, glass, ceramics, wood, or plastic. The coating increases the pull-out strength of the coated nails.

[0008] CN 107686768 A discloses an abrasion-resistant lubricant comprising, among other things, base oil, nano-scale metal microspheres, graphene and a soap thickener, as well as a method for producing the lubricant.

[0009] JP H05-320685 A discloses a composition for producing coatings on aluminium plates, wherein the composition contains a water-soluble lubricating polymer wax, a metal soap and a conductive powder.

[0010] EP 2210931 A1 discloses a lubricant coating for threaded pipe connections, comprising rosin and / or calcium fluoride, a metal soap, a wax and a basic metal salt of an aromatic organic acid and preferably further magnesium carbonate, a carbohydrate, in particular a cyclodextrin, and / or a lubricating powder such as graphite.

[0011] EP 2110427 A1 discloses a sliding material composition comprising a resin, porous, preferably spherical, silicon dioxide and a lubricant such as a silicone oil.

[0012] It is also known that the use of inorganic particles in surface coatings can lead to wear due to the size, hardness and morphology of many particulate solids, e.g. to scratches on steel or aluminium surfaces. Object of the invention

[0013] The object of the invention is to provide a coating agent for screws with the aim of adjusting the coefficient of friction of the screw during multiple tightening operations against various material surfaces such as aluminum, steel, and e-coatings by means of the lubricating film. The total coefficient of friction and partial coefficients of friction should lie within the narrowest possible range and be as similar as possible even when the screw head is mating against different materials. If the total value is too low, e.g., significantly lower than 0.08, there is a risk that the screw will loosen from the screw connection on its own. Furthermore, if the coefficient of friction is too low, the screw may break when tightened to a predetermined torque. Summary of the invention

[0014] The problem is solved by the subject matter of the independent claims. These relate to a lubricant composition, a lubricating film, and a lubricant concentrate. Advantageous embodiments are the subject matter of the dependent claims or are described below.

[0015] Surprisingly, it was found that a lubricating film comprises the following basic composition: A first wax B a second wax, and C microspherical inorganic particles as solid bodies, achieve special friction properties on screws.

[0016] The base composition consists solely of the first wax A, the second wax B, and microspherical inorganic particles C. However, the lubricating film and lubricant composition contain additional components beyond those of the base composition, such as additives or, in the case of the lubricant composition, water. Therefore, the base composition is a hypothetical composition that exists only during the manufacturing process and always contains at least one additional component.

[0017] The base composition contains the following: First wax A, second wax B and microspherical inorganic particles C: - the weight ratio of A : B is from 10 : 1 to 1 : 1; and - the weight ratio of (A + B) : C is from 5 : 1 to 1 : 3.

[0018] The lubricant composition is a dispersion comprising a solid and a liquid phase, wherein the liquid phase comprises or consists of water and the solid phase comprises at least the base composition described above. The first wax A and the second wax B are present in the dispersion in the form of wax particles, wherein the first wax A, the second wax B, and the microspherical inorganic particles C together constitute at least 5 wt.%, preferably at least 8 wt.%, of the lubricant composition.

[0019] Preferably, 10 to 50 wt.% of the lubricant composition is the solid phase and / or 10 to 50 wt.% of the lubricant composition is the solids content.

[0020] The lubricant composition is preferably liquid at room temperature (25 °C).

[0021] The first wax A is selected from one or more members of the group consisting of: polypropylene wax, modified polypropylene wax, ethylene-acrylic acid copolymer, and ethylene-methacrylic acid copolymer. Polypropylene wax and / or modified polypropylene wax are preferred.

[0022] The second wax B is selected from one or more members of the group consisting of carnauba wax, sugar cane wax, ethylene bis-stearamide wax, polyethylene wax, modified polyethylene wax, Fischer-Tropsch wax, modified Fischer-Tropsch wax, paraffin wax, and modified paraffin wax. Polyethylene wax, Fischer-Tropsch wax, modified polyethylene wax, and / or modified Fischer-Tropsch wax are preferred.

[0023] Paraffin waxes differ from polypropylene waxes and do not exhibit the sequence of methyl branches typical of polypropylene waxes.

[0024] The modified waxes mentioned above are, for example, partially oxidized. The modification can also consist of grafting with unsaturated anhydrides such as maleic anhydride; in particular, grafting with maleic anhydride applies to modified polypropylene wax.

[0025] The microspherical inorganic particles are solid bodies, preferably of inorganic oxide materials, in particular selected from one or more members of the group consisting of: alkali aluminosilicates, aluminum oxides, borosilicate glasses or clay minerals, or from products obtainable by calcining the clay minerals, e.g. calcining at over 400 °C in ambient air.

[0026] The lubricating film on the screw allows for the setting of defined friction coefficients that remain within a narrow range even during multiple tightening operations and against different surfaces such as aluminum, steel, and e-coating. This friction coefficient range is significantly narrower than that for the same screw with a lubricating film lacking microspherical inorganic particles. A particularly noticeable effect is achieved when tightening against aluminum as the counter-surface, significantly reducing the head friction coefficients during multiple tightening operations. Furthermore, the combination of the two waxes makes it possible to set thread and head friction coefficient ranges within the preferred range of 0.08 to 0.16 during five tightening operations; preferably, overall friction coefficients against the various counter-surfaces should average 0.12.

[0027] Such narrow friction coefficient ranges against different surfaces cannot be achieved with lubricating films containing only the first or only the second wax alone. By using the two different waxes and the microspherical inorganic particles as solid particles, it is possible to achieve practically applicable friction coefficients with a low scatter, even with different material pairings such as steel / steel, steel / aluminum, and steel / e-coating.

[0028] The lubricating film can be obtained, for example, by applying the lubricant composition to the screws by dipping or spraying. The lubricant composition is liquid at room temperature and can wet the screw.

[0029] The preferred basic composition A + B + C is composed as follows: A: 15 to 65 GT, especially preferred 20 to 53 GT, of the first wax, B: 3 to 40 GT, especially preferred 5 to 35 GT of the second wax and C: 10 to 70 GT, particularly preferably 15 to 55 GT microspherical inorganic particles as solid bodies, wherein A + B + C always result in 100 GT, and with respect to the components A, B and C: - the weight ratio of A : B is between 10 : 1 and 1 : 1; and - the weight ratio of (A + B) : C is from 5 : 1 to 1 : 3.

[0030] The lubricating film and the lubricant composition, the latter only in relation to the solids content, may, in addition to the obligatory basic composition A + B + C, optionally contain, among other things, binders, additives, sealants and / or solid lubricants: • greater than 25 wt.% base composition consisting of A + B + C, • optional 0 to 75 wt.% binder, e.g. 0.1 to 75 wt.% binder, preferably 15 to 55 wt.% if available; • optional 0 to 35 wt.% additives, e.g. 1 to 30 wt.% additives, preferably 5 to 28 wt.%; • optional 0 to 30 wt.% sealant, e.g. 0.01 to 30 wt.% sealant; • optional 0 to 20 wt.% solid lubricants, e.g. 0.01 to 20 wt.% solid lubricants; based on the total weight of the lubricating film or based on the solids content of the lubricant composition.

[0031] The solid content of the lubricant composition, or the lubricant composition or the lubricating film, if it contains a binder, preferably A, B and C in a total of 25 to 99.9 wt, preferably 45 to 85 wt; and the binder of 0.1 to 75 wt, preferably 15 to 55 wt, based on the solids content of the binder, wherein the sum of A + B + C + solids content of the binder yields 100 wt.

[0032] According to another embodiment for a lubricant composition or a lubricating film without binders, the lubricant composition or the lubricating film each comprise: The first wax A of 12 to 65 wt.%; preferably 17 to 53 wt.%; the second wax B in 2 to 40 wt.%; preferably in 4 to 35 wt.%; the microspherical oxide particles C of 8 to 70 wt.%; preferably of 12 to 55 wt.%; for the lubricant composition with regard to the solids content of the lubricant composition and for the lubricating film in relation to the total weight of the lubricating film.

[0033] The lubricant composition or lubricating film, after formulation with binder, each comprises: the base composition A + B + C from 20 to 99.9 wt.%, preferably 35 to 85 wt.%; the binder in a concentration of 0.1 to 75 wt.%, preferably 12 to 55 wt.%; for the lubricant composition with regard to the solids content of the lubricant composition and for the lubricating film in relation to the total weight of the lubricating film.

[0034] The solids content refers to the mass fraction of a coating material that remains as a non-volatile residue after evaporation. The solids content as a non-volatile fraction can be determined by evaporation in a drying oven at 130 °C until a constant weight is achieved (in accordance with DIN EN ISO 3251 - 2019-09).

[0035] In the lubricant composition, the waxes are present as wax dispersions. These are dispersed solid particles of waxes, which are dispersed in water with dispersants and / or stabilizers and, if necessary, preservatives for preservation. The lubricant composition is a solid dispersion (which does not preclude the simultaneous emulsification of certain liquid components), with the particle size of the wax particles being measured as solid particles of wax A and wax B as particle diameter d. 90preferably less than 30 µm, in particular less than 20 µm or even less than 10 µm.

[0036] The microspherical inorganic particles C are preferably essentially round solid bodies, in particular solid spheres, with solid spheres being preferred due to their better resistance in screw threads.

[0037] The microspherical oxide particles C preferably have a particle diameter of: d 90 greater than 2 µm and less than 30 µm, preferably d 90 greater than 3 µm and less than 25 µm, particularly preferably d 90 smaller than 20 µm; and / or d 50 larger than 1 µm and smaller than 20 µm, preferably d 50 greater than 1.5 µm and less than 12 µm, particularly preferably d 50 smaller than 8 µm.

[0038] The particle diameters can each be determined by light scattering.

[0039] The sphericity of microspherical inorganic particles can range from 0.90 to 1.00, particularly from 0.95 to 1.00, as determined by dynamic image analysis according to ISO 13322-2 (2006). As described in ISO 13322-2 (2006), the sphericity can be determined by dynamic image analysis, e.g., using a Camsizer from Retsch. The sphericity (SPHT3) is calculated from the measured circumference P and the area A of the particle projection using the following equation. SPHT3=4πAp2 and is volume-based. The determined value is dimensionless and would be 1 for an ideal sphere and is typically less than 1 for spherically shaped particles that are not ideal spheres.

[0040] Examples of inorganic spherical particles are silicates such as alkali aluminosilicate ceramics. One example is the commercial product Ceramic Microspheres W-210 (particle diameter d). 90 = 12µm) or Ceramic Microspheres W-410 (particle diameter d 90= 21µm).

[0041] Binders have the task of binding the individual formulation components, after solidification, into a coating that adheres well to the substrate and is wear-resistant. The binder acts as a matrix, influencing corrosion protection properties, abrasion resistance, water resistance, chemical resistance, temperature resistance, flexibility / elasticity, hardness, hot solubility, as well as gloss and color. Depending on the material, organic and / or inorganic binders can be used.

[0042] According to the present invention, binders based on acrylates, epoxides, or polyurethanes are used, for example. Examples include the acrylate-based binders NuVera AC-22 or NuVera AC-69 from Stahl.

[0043] Sealants may also be used in the lubricating film or in the lubricant composition. In electroplated zinc-nickel pretreatments, a sealant is frequently used to close the pores present in the zinc-nickel plating, thus improving corrosion protection.

[0044] The sealant can be applied to the screw before the lubricant or together with the lubricant. The sealant restricts the access of oxygen and / or moisture to the metallic substrate or protects the metal surface via electrochemical reaction mechanisms. The sealant consists of at least binders and / or additives and / or fillers. The sealant is free of components A, B, and C. For example, sealants contain binders together with colloidal silicon dioxide or condensed siloxanes, or surface-modified SiO2 particles with siloxanes or organofunctional silanes (Dynasylan SIVO 110 from Evonik or Ludox AS40 from Grace). A suitable sealant is Silco CT 9900 (Keim Additec), which contains, among other things, organofunctionalized silanes. Another sealant is Sealer 300W from Atotech.

[0045] Additives are used to adjust the properties of the lubricating film or the lubricant composition. Additives that can be used include emulsifiers / stabilizers, preservatives, corrosion inhibitors, anti-sedimentation additives, wetting and leveling additives, defoamers, and / or UV additives.

[0046] Emulsifiers serve to improve the dispersion of wax particles in water in order to obtain homogeneous and stable wax dispersions. Examples include ethoxylated linear and / or branched alcohols such as ethoxylated C9 to C11 alcohols (CAS 68439-46-3, e.g., TERGITOL™ 91-6 Surfactant from Dow).

[0047] Preservatives serve to preserve the formulation and protect it from contamination by microorganisms and molds. For example, formaldehyde releasers such as EDDM ((ethylenedioxy)dimethanol) or TMAD (tetrahydro-1,3,4,6-tetrakies-(hydroxymethyl)-imidazo-[4,5-d]-imidazol-2,5-(1H,3H)-dione), isothiazolones such as MIT (methylisothiazolone), pyrithiones, or organobromides can be used.

[0048] Corrosion protection additives protect metallic substrates from corrosion in various ways. Examples of corrosion protection additives include corrosion protection pigments based on phosphates such as zinc phosphates, and corrosion inhibitors that coat the metal surface, such as sulfonates, zinc 5-nitroisophthalate, or sebacates.

[0049] Coatings often combine several additives to achieve sufficient corrosion protection (binders with high network density, use of corrosion protection additives, fillers with barrier effect, hydrophobic components, etc.).

[0050] Anti-sedimentation additives act either by increasing viscosity as a rheology additive or by modifying the surface of the solids to be stabilized; some combine both properties. Additives with shear-thinning, thixotropic, or pseudoplastic flow behavior are often used to increase viscosity; these liquefy easily under mechanical stress such as stirring. They protect against sedimentation at rest and simultaneously enable the necessary lower viscosity ranges for coating (spraying, immersion centrifugation, etc.). Examples include layered silicates such as bentonite or laponite, urea derivatives, acrylates, polyurethanes, or polyamides.

[0051] Anti-sedimentation additives that act via chemical surface modification are anchored to the solid to be stabilized (adsorptively or through chemical bonding) and exert a steric, electrostatic, or electrosteric stabilizing effect. For example, silanes can be used to stabilize oxide solids containing hydroxide groups. These silanes are anchored to the solids through a condensation reaction. The silanol group serves as the anchoring group, while the organic residue determines the stabilizing properties. There are also chemical surface modifiers that additionally form a network, thus separating the particles from one another.

[0052] Wetting and leveling additives improve the wetting of the coating medium on the substrate and enable the formation of a homogeneous coating. Their mode of action is based on reducing the surface tension of the coating medium. Examples include polysiloxanes, polyacrylates, silicone-containing or silicone-free surfactants such as polyether-modified siloxanes or alcohol alkoxylates.

[0053] Defoamers help trapped air bubbles escape from the coating material by destabilizing the foam lamellae. For example, polysiloxanes, paraffin-based mineral oils, or polymer defoamers (e.g., polyolefins) can be used, which are combined with hydrophobic particles.

[0054] UV additives can be used to make the applied coating material visible under UV light, allowing for inspection of the coating's homogeneity. UV-active fluorescent dyes, for example, can be used as UV additives.

[0055] Solid lubricants in sliding films and coatings are used to achieve defined coefficients of friction. They are a component of the coating material and are firmly bound within the sliding film / coating. In tribological contact, their specific physicochemical properties, such as crystalline layer structure or anti-adhesive properties, influence the sliding behavior of the tribological partners. Examples of solid lubricants include graphite, zinc oxide, tricalcium phosphate, calcium carbonate, molybdenum disulfide, tungsten sulfide, hexagonal boron nitride, and / or polymers such as PTFE, silicones, polysulfides, etc., or mixtures of the aforementioned materials. However, solid lubricants can also be omitted, particularly fluorinated solid lubricants. Detailed description of the invention

[0056] When screwing components together, screws, nuts and bolts and, if necessary, washers and / or shims are used.

[0057] The lubricating film should enable total friction coefficients between 0.08 and 0.16, preferably around 0.12.

[0058] The two types of wax in the lubricating film produce different coefficients of friction on the bolted joint components. The first wax alone produces a higher coefficient of friction, and the second wax alone produces a lower coefficient of friction; therefore, the coefficients of friction lie at least partially (total and / or partial coefficients of friction) outside the desired range, both with and without the use of the microspherical inorganic particles.

[0059] Typically, for the first wax, a large proportion of the total and / or partial friction coefficients are above the desired friction coefficient range; in particular, the head friction coefficients are significantly above the desired range when applied to aluminum. For the second wax, a large proportion of the total and / or partial friction coefficients are below the desired friction coefficient range; in particular, the head friction coefficients are significantly below the desired range when applied to e-coating and steel.

[0060] By mixing both types of wax, it is surprisingly possible to adjust the desired coefficient of friction range, whereby normally, without the use of microspherical inorganic particles, some head friction values ​​are too low against steel and / or KTL, while against aluminum some head friction values ​​are too high, so that some friction values ​​(thread friction, head friction, total friction) are outside the target corridor.

[0061] In addition to the two types of wax, the different material pairings naturally influence the coefficient of friction. The surface of the aluminum counter-surface is chemically determined by aluminum oxides and aluminum hydroxides, while the steel surface is characterized by the alloy composition (Fe, Cr, Mn, Ni...) and its oxides.

[0062] The KTL (cathodic dip coating) coating generally consists of an epoxy-based binder, pigments, and additives. This results in various chemical and physical interactions between the contacting surfaces of the bolted components and the lubricating film during tribological contact.

[0063] The coefficient of friction is also influenced by the screw geometry. Using different screw sizes results in varying mechanical conditions (thread pitch, surface pressure in the thread, etc.), which can lead to different coefficients of friction when applying a lubricating film to different screw sizes. Particularly significant differences are observed in the thread friction coefficients; these are often considerably higher on small M6 screws than on larger screws.

[0064] The aim of the invention was to adjust the coefficient of friction for different material pairings by modifying the composition of the lubricating film. In addition to the wax mixture, the microspherical inorganic particles play a significant role, as they make it possible to significantly reduce the deviations (variances) of the desired coefficient of friction.

[0065] When using microspherical inorganic particles in lubricating films on the screw elements, it was observed that the scatter of the head friction coefficients against aluminum narrowed in five tightening cycles, and the increase in friction coefficient from the first to the last tightening cycle was significantly lower. Thus, by adding microspherical inorganic particles to formulations that previously exhibited excessively high head friction coefficients in screw connections against aluminum, the head friction coefficient can be reduced to the desired range. When pairing steel against e-coating or steel against steel, the absolute head friction coefficients are lower than with aluminum when using the lubricating film, and often too low. The use of microspherical inorganic particles tends to raise this head friction coefficient level rather than lowering it.By using microspherical inorganic particles, the head friction coefficient range can be shifted into the target corridor for the three material pairings described.

[0066] Another effect is observed with M6 screws with integrated washers. Due to the integrated washer, which is coated along with the screw head during the coating process, the friction coefficient is often particularly low, as not only the screw but also the mating surface is coated. Consequently, the friction coefficient of the M6 ​​screw head is often below the desired range. By using microspherical inorganic particles, this friction coefficient can be significantly increased.

[0067] Another advantage of the microspherical inorganic particles in the lubricating film lies in their effect on thread friction coefficients. The thread friction coefficients, especially of smaller screws (M6), can increase significantly with repeated tightening. By using microspherical inorganic particles in the lubricating film, this increase is considerably reduced, resulting in less variation in thread friction coefficients, even after multiple tightening operations of up to five times.

[0068] The advantage of microspherical inorganic particles lies in the fact that their use in the lubricant ensures that the three material pairings of screw and mating surface (steel / aluminum; steel / e-coating; steel / steel) are within the same head friction coefficient range and can be coated with the same lubricating film. In addition to the head friction coefficients, the thread friction coefficients also fall within a narrow range across all tightenings, thus meeting all friction requirements for the various screw sizes.

[0069] The production of the lubricating films is characterized by the following work steps: - Production of the lubricant composition, - Coating of the screws with the liquid lubricant composition - followed by drying, whereby the liquid lubricant composition is converted into a solid lubricating film.

[0070] Afterwards, the friction coefficients for the screws coated with the lubricating film can be determined in a screw test rig.

[0071] The lubricant composition can also be provided as a lubricant concentrate, which can be further diluted with water.

[0072] The lubricant concentrate includes: 35 to 70 wt.% water and in terms of solids content: a first wax A in the form of wax particles of 12 to 65 wt.%; preferably 17 to 53 wt.%, a second wax B in the form of wax particles of 2 to 40 wt.%; and preferably of 4 to 35 wt.%, microspherical oxide particles C as solid particles of 8 to 65 wt.% and preferably of 12 to 50 wt.%, where the first wax A is selected from one or more members of the group consisting of: Polypropylene wax, modified polypropylene wax, ethylene-acrylic acid copolymer and ethylene-methacrylic acid copolymer where the second wax B is selected from one or more members of the group consisting of: Carnauba wax, sugar cane wax, ethylene bis-stearamide wax, polyethylene wax, modified polyethylene wax, Fischer-Tropsch wax, modified Fischer-Tropsch wax, paraffin wax and modified paraffin wax, where - the weight ratio of A : B is between 10 : 1 and 1 : 1; and - the weight ratio of (A + B) : C is from 5 : 1 to 1 : 3.

[0073] For the lubricant concentrate, the first wax A, the second wax B and the microspherical oxide particles C are defined in the same way, also with regard to preferred variants as above for the lubricant composition, also with regard to any further ingredients lubricant composition such as binders, additives, sealants and / or solid lubricants. Experimental examples (Experimental part)

[0074] The figures show: Fig. Figure 1 shows the head friction values ​​against the counter surfaces KTL and aluminium over 5 tightenings of 5 screws each, M10x55 zinc-nickel silver with a lubricating film without microspheres. Fig.Figure 2 shows the head friction coefficients against the counter surfaces KTL and aluminum over 5 tightenings each of 5 M10x55 silver zinc-nickel screws with the same composition of a lubricating film but additionally containing microspheres. The gray background indicates the friction coefficient range that needs to be set.

[0075] In the experimental section, the microspherical inorganic particles are referred to simply as "microspheres".

[0076] The raw materials are addressed below with reference to the term in the "Component" column of Table 1. The following section describes the production of various lubricating films and the coating of screws, including the testing and characterization on a screw test bench.

[0077] The raw materials used were: Table 1 component Trade name Manufacturer Material description Wax 1a ULTRALUBE® GA6667 Keim additecsurface GmbH Polypropylene wax in dispersion Wax 1b LUBA-print® 466 / F MÜNZINGCHEMIE GmbH modified polypropylene wax in dispersion Wax 1c TECSEAL E-805 Trüb EmulsionsChemie AG Ethylene methacrylic acid copolymer dispersion Wax 2a DEUREX® E 1101 W DEUREX AG Polyethylene wax in dispersion Wax 2b DEUREX® EO 4508 W DEUREX AG oxidized HDPE wax dispersion Wax 2c Hydrowax 5080 Sasol Wax GmbH synthetic Fischer-Tropsch wax in dispersion Microspherical particles 3M™ Ceramic Microspheres W-210 3M Germany GmbH Alkaline aluminosilicate ceramic solid balls Thickener KELZAN® CP KelcoFrance Xanthan Anti-withdrawal medication RHEOBYK-7420 ES BYK-ChemieGmbH modified urea UV additive Tinopal® SFP BASF SE fluorescent optical brightener Biocide ACTICIDE MB Thor GmbH Isothiazolone Progressive additive TEGO® Wet 250 Evonik Operations GmbH Polyether-modified trisiloxane Liability mediator Dynasylan® HYDRO-SIL 2926 Evonik Operations GmbH oligomeric hydroxy-functional silane hydrolysate binder NuVera® AC-22 Stahl Europe BV Acrylic copolymer Water Example 1: Experiments on lubricant compositions with wax 1a and wax 2a with and without microspheres

[0078] A 3% thickener solution was prepared. For this, an appropriate amount of the thickener was dispersed with water in a homogenizer at room temperature for 60 minutes while stirring. Water was placed in a stainless steel beaker, and wax 1a, the 3% thickener solution, and the UV additive were added. The mixture was then dispersed in the homogenizer at 1500 rpm for 10 minutes.

[0079] The microspheres and anti-settling agent were then added, and the mixture was homogenized for a further 15 minutes (excluding lubricant composition 1a). Finally, the wax 2a, biocide, flow additive, and adhesion promoter were added and homogenized for 15 minutes at 1000 rpm.

[0080] Table 2 shows the different lubricant compositions as liquid formulations 1a to 1d. All components of the lubricant compositions together comprised 100 wt.%. The weight ratios given refer to the weight fractions of wax 1a : wax 2a : microspheres in the dry layer or based on the solids content. The wax dispersions wax 1a and wax 2a each have a solids content of 35 wt.%. Table 2 Lubricant compositions Example 1 1a 1b 1c 1d Weight percentages of wax 60,45 / 47,13 / 40,12 / 22,97 / 1 a* / Wax 2a* / 22,61 / 17,63 / 15,0 / 8,59 / Microspheres 0 17,49 29,77 56,84 GT for Wax 1a * / 72,78 / 57,30 / 47,26 / 25,98 / Wax 2a * / 27,22 / 21,43 / 17,67 / 9,72 / Microspheres = 100 GT of the basic composition 0 21,26 35,07 64,30 Relationship 2,7 : 2,7 : 2,7 : 2,7 : Wax 1a*: Wax 2a*: 1 : 1 : 1 : 1 : Microspheres 0 1 2 6,6 Lubricant composition [Weight %] [Weight %] [Weight %] [Weight %] Water ** 39,8 66,75 64,25 71,03 Wax 1a 38,5 19,25 19,25 11,55 Wax 2a 14,4 7,2 7,2 4,32 Microspheres - 2,5 5 10,0 Thickener 0,3 0,3 0,3 0,3 Anti-withdrawal medication - 0,5 0,5 0,7 UV additive 0,9 0,45 0,45 0,27 Biocide 0,2 0,1 0,1 0,06 Progressive additive 0,9 0,45 0,45 0,27 Liability mediator 5,0 2,5 2,5 1,5 Total % 100 100 100 100 * in relation to the solids content of the respective wax dispersion. Base composition = only wax 1a as solids, wax 2a as solids and microspheres; ** additionally added water, GT = parts by weight

[0081] The application to the screws (M10x55 ZnNi silver and M6x55 ZnNi silver) was carried out using a dip-spin method with a centrifuge. The screws were dipped into the respective lubricant compositions 1a to 1d for a few seconds and then spun in a laboratory centrifuge for 20 seconds at 300 rpm. Immediately afterwards, the screws were dried for 30 minutes at 80 °C in a drying oven under an air atmosphere. After drying, a non-slip lubricating film remained on the screws.

[0082] The testing characterization of the screws coated with the dried lubricant compositions was carried out in a screw test rig according to MBN standard 10544-2019 or VW 01131. Another method for determining the coefficient of friction of screws is described in VDA 235-203.

[0083] Table 3 shows the total and partial friction coefficients for silver zinc-nickel (Zinc-Ni) M10x55 hexagonal flange screws coated with films of lubricant compositions 1a to 1d against steel, e-coated (KTL), and aluminum head surfaces with a plain steel (bare) hexagonal nut. The friction coefficient range for each set of 5 measured screws over 5 tightening cycles is given. The measurement procedure was carried out according to standard MBN 10544 (edition 01 / 2019).

[0084] For better clarity and direct comparison, in Fig. 1 and Fig. 2 the head friction coefficients of Table 3 are shown, namely for lubricant composition 1a ( Fig. 1) without microspheres and for lubricant composition 1d with microspheres ( Fig.2, according to the invention). The head friction coefficients against KTL and aluminum were shown. The friction coefficient ranges for five measured screws over five tightenings, µK1 to µK5, are depicted, where µK1 corresponds to the head friction coefficient of the first tightening. It is clearly visible that the head friction coefficients against KTL and aluminum as the counter-surface without the microspheres differ considerably and were largely outside the preferred friction coefficient range of 0.08 to 0.16. With the addition of the microspheres, the head friction coefficients against both counter-surfaces became much closer and were approximately at the same level within the preferred friction coefficient range.

[0085] Without the addition of microspheres, the head friction coefficients against aluminum increased sharply to over 0.3 across the five suits (for lubricant composition 1a), while the head friction coefficients against e-coating were sometimes less than 0.08. By adding microspheres in increasing amounts from lubricant composition 1a to 1d, the head friction coefficients against aluminum were significantly reduced, so that the head friction coefficients across the five suits now lay within a narrow friction coefficient range. Meanwhile, the head friction coefficients against steel and e-coating increased with increasing amounts of microspheres, and the friction coefficients against the three different materials thus converged, resulting in total friction coefficients close to the target value of 0.12 for all three materials.

[0086] The investigations were repeated for lubricant composition 1a and 1d, this time as a film on M6x55 silver zinc-plated internal hexagon combination screws with integrated washer; the coefficients of friction of 5 measured screws were recorded over 5 tightenings with electrolytically zinc-plated square weld nut; measurement method according to VW 01131 (2018-03).

[0087] The comparison of the friction coefficients for M6 screws in Table 4 with films made of lubricant composition 1a and 1d shows the influence of the microspheres on the friction coefficients.

[0088] Without microspheres, the thread friction coefficients rose to as high as 0.3. The difference compared to the measured values ​​on M10 screws was very large. The head friction coefficients, however, were within the desired range. By adding microspheres, the thread friction coefficient could be reduced to a maximum of 0.13, while the head friction coefficient increased to approximately 0.13 to 0.15, resulting in a total friction coefficient of approximately 0.12 to 0.14. Example 2: Experiments on lubricant compositions with wax 1b and wax 2b with and without microspheres

[0089] The production process was the same as in Example 1, however, wax 1b was used instead of wax 1a and wax 2b was used instead of wax 2a.

[0090] Table 5 corresponds to Table 2 but for lubricant compositions 2a to 2c.

[0091] The application to the screws (M10x55 ZnNi silver) was carried out as for example 1. Table 5 Lubricant compositions Example 2 2a 2b 2c Weight percentages of wax 1b* / 49,38 / 32,76 / 18,75 / Wax 2b* / 33,67 / 22,34 / 12,79 / Microspheres 0 29,78 56,85 GT for wax 1 b* / 59,46 / 38,60 / 21,21 / Wax 2b* / 40,54 / 26,31 / 14,47 / Microspheres = 100 GT of the base composition 0 35,09 64,32 Ratio of wax 1b : 1,5 : 1,5 : 1,5 : Wax 2b : 1:0 : 1 : 1 : Microspheres 0 1,3 4,4 Lubricant composition [Weight %] [Weight %] [Weight %] Water ** 50,2 69,45 74,15 Wax 1b 27,5 13,75 8,25 Wax 2b 15 7,5 4,5 Microspheres - 5 10,0 Thickener 0,3 0,3 0,3 Anti-withdrawal medication - 0,5 0,7 UV additive 0,9 0,45 0,27 Biocide 0,2 0,1 0,06 Progressive additive 0,9 0,45 0,27 Liability mediator 5,0 2,5 1,5 Total % 100 100 100 * in relation to the solids content of the respective wax dispersion. Base composition = only wax 1a as solids, wax 2a as solids and microspheres; ** additionally added water, GT = parts by weight

[0092] Table 6 shows the coefficients of friction as shown in Table 3.

[0093] Without the addition of microspheres, the head friction coefficients against aluminum increased to as high as 0.25 across the five suits, while the head friction coefficients against e-coating were very low (lubricant composition 2a). With increasing proportions of microspheres, the head friction coefficients against aluminum were significantly reduced, while the head friction coefficients against e-coating and steel were increased. With the highest proportion of microspheres (lubricant composition 2c), this effect was significantly amplified, and an overall friction coefficient of approximately 0.1 to 0.11 could be achieved against all head surfaces, with the friction coefficients being at the same level for all material pairings. Example 3: Experiments on lubricant compositions with wax 1c and wax 2c with and without microspheres

[0094] The production process was the same as in Example 1, however, wax 1c was used instead of wax 1a and wax 2c was used instead of wax 2a.

[0095] Table 7 corresponds to Table 2 but for lubricant compositions 3a to 3c. Table 7 Lubricant compositions Example 3 3a 3b 3c Weight percentage of wax 1c* / 79,56 / 49,85 / 28,54 / Wax 2c *, / 6,99 / 5,25 / 3,01 / Microspheres 0 29,78 56,85 GT for wax 1c* / 91,93 / 58,73 / 32,29 / Wax 2c* / 8,07 / 6,19 / 3,40 / Microspheres = 100 GT of the basic composition 0 35,08 64,31 Relationship 9,5 : 9,5 : 9,5 : Wax 1c* : Wax 2c* : 1 : 1 : 1 : Microspheres 0 5,7 18,9 Screw size used M10X55 M10X55 M10X55 Lubricant composition [Weight %] [Weight %] [Weight %] Water ** 32,98 60,84 68,98 Wax 1c 55,8 27,9 16,74 Wax 2c 3,92 1,96 1,18 Microspherical particles - 5 10,0 Thickener 0,3 0,3 0,3 Anti-withdrawal medication - 0,5 0,7 UV additive 0,9 0,45 0,27 Biocide 0,2 0,1 0,06 Progressive additive 0,9 0,45 0,27 Liability mediator 5,0 2,5 1,5 Total % 100 100 100 * in relation to the solids content of the respective wax dispersion. Base composition = only wax 1a as solids, wax 2a as solids and microspheres; ** additionally added water, GT = parts by weight

[0096] The application to the screws (M10x55 ZnNi silver) was carried out as for Example 1. The friction coefficients are shown in Table 8 as for Table 3.

[0097] Without the addition of microspheres, the head friction coefficients against aluminum increased to just under 0.25 across the five suits, while the head friction coefficients against e-coating were very low (lubricant composition 3a). With an increasing proportion of microspheres, the head friction coefficients against e-coating and steel increased and were within the desired range (lubricant composition 3c), and the head friction coefficients against aluminum were also within the friction coefficient range of 0.08 to 0.16. The overall friction coefficients against the various surfaces became more similar. Example 4: Experiments on lubricant compositions with wax 1a and wax 2a with microspheres and binder

[0098] The preparation was carried out as in Example 1c. Finally, however, 25 parts by weight of binder were added to the lubricant composition 1c (100 parts by weight), and homogenization was carried out for a further 5 minutes. Lubricant composition 4 is obtained. Table 9 Example 4 Lubricant composition 4 Weight percentages of wax 1a* / 25,14 / Wax 2a* / 9,40 / Microspheres / 18,66 / binder 37,32 GT for Wax 1a* / 27,77 / Wax 2a* / 10,39 / Microspheres / 20,61 / Binder = 100 g (base composition plus binder) 41,22 ratio of wax 1a: 2,7 : Wax 2a: 1 : Microspheres: 2 : binder 4,0

[0099] The application to the screws (M10x55 ZnNi silver) was carried out as for Example 1. The friction coefficients are shown in Table 10 as for Table 3.

[0100] The use of the binder in the formulation results in overall higher coefficients of friction than without a binder. Without a binder, formulation example 1c in Table 3 shows head friction coefficients in the range of 0.08 against e-coat and low and stable values ​​against aluminum over five passes. Adding the binder increases the overall values, improving the head friction coefficients against e-coat to between 0.09 and 0.1, while the head friction coefficients against aluminum remain stable over five passes, reaching a maximum of approximately 0.14. Overall, good total coefficients of friction between 0.11 and 0.14 are achieved against all surfaces.

Claims

[1] Lubricant composition, wherein the lubricant composition is a dispersion comprising a solid and a liquid phase, and the fixed phase includes: - a first wax A in the form of wax particles, where the first wax is selected from one or more members of the group consisting of: Polypropylene wax, modified polypropylene wax, ethylene-acrylic acid copolymer and ethylene-methacrylic acid copolymer; - a second wax B in the form of wax particles, where the second wax is selected from one or more members of the group consisting of: Carnauba wax, sugar cane wax, ethylene bis-stearamide wax, polyethylene wax, modified polyethylene wax, Fischer-Tropsch wax, modified Fischer-Tropsch wax, paraffin wax and modified paraffin wax; and - microspherical inorganic particles C as solid bodies; where - the weight ratio of A : B is between 10 : 1 and 1 : 1; and - the weight ratio of (A + B) : C is from 5 : 1 to 1 : 3; and the liquid phase includes: - at least water; wherein the sum of first wax A, second wax B and microspherical inorganic particles C together constitutes at least 5 wt.%, preferably at least 8 wt.%, of the lubricant composition. [2] Lubricant composition according to claim 1, wherein the solid phase constitutes 10 to 50 wt.% of the lubricant composition. [3] Lubricant composition according to at least one of the preceding claims, wherein the first wax A is selected from one or more members of the group: Polypropylene wax and modified polypropylene wax. [4] Lubricant composition according to at least one of the preceding claims, wherein the second wax B is selected from one or more members of the group: Polyethylene wax, Fischer-Tropsch wax, modified polyethylene wax and modified Fischer-Tropsch wax. [5] Lubricant composition according to at least one of the preceding claims, wherein the first wax A or the second wax B or both have a particle diameter of d 90 smaller than 30 µm preferred d 90 exhibit dimensions smaller than 10 µm. [6] Lubricant composition according to at least one of the preceding claims, wherein the microspherical inorganic particles C are oxide inorganic materials, in particular selected from one or more members of the group consisting of: Alkali aluminosilicates, aluminum oxides, borosilicate glasses, clay minerals and products obtainable by calcining clay minerals. [7] Lubricant composition according to at least one of the preceding claims, wherein the microspherical oxide particles C have a particle diameter of: - d 90 smaller than 30 µm, preferably d 90 smaller than 25 µm, especially preferred d 90 smaller than 20 µm; and / or - d 50 smaller than 20 µm, preferably d 50 smaller than 12 µm, especially preferred d 50 less than 8 µm. [8] Lubricant composition according to at least one of the preceding claims, wherein the microspherical oxide particles C have a particle diameter of: - d 90 greater than 2 µm, especially greater than 3 µm; and / or - d 50 greater than 1 µm, especially greater than 1.5 µm. [9] Lubricant composition according to at least one of the preceding claims, wherein the microspherical particles C have a sphericity greater than 0.9, in particular greater than 0.

95. [10] Lubricant composition according to at least one of the preceding claims, wherein the lubricant composition comprises, in relation to the base composition consisting of A, B and C, respectively: - the first wax A of 15 to 65 parts by weight (Wt), preferably of 20 to 53 Wt; - the second wax B from 3 to 40 GT, preferably from 5 to 35 GT; - the microspherical oxide particles C of 10 to 70 GT, preferably 15 to 55 GT; wherein the sum of A + B + C = 100 GT. [11] Lubricant composition according to at least one of the preceding claims, each comprising a further binder, wherein the sum of A, B and C is from 25 to 99.9 GT, preferably from 45 to 85 GT; and the binder comprises 0.1 to 75 parts by weight, preferably 15 to 55 parts by weight, based on the solids content of the binder; and where the sum of A + B + C + solids of the binder = 100 GT. [12] Lubricant composition according to at least one of claims 1 to 11, each comprising: no binder the first wax A of 12 to 65 wt.%, preferably 17 to 53 wt.%; the second wax B in 2 to 40 wt.%, preferably in 4 to 35 wt.%; the microspherical oxide particles C of 8 to 70 wt.%, preferably of 12 to 55 wt.%; with regard to the solids content of the lubricant composition. [13] Lubricant composition according to at least one of the preceding claims 1 to 12, each further comprising a binder, comprising: the components A + B + C in amounts of 20 to 99.9 wt.%, preferably 35 to 85 wt.%, the binder in a concentration of 0.1 to 75 wt.%, preferably 12 to 55 wt.%; with regard to the solids content of the lubricant composition. [14] Lubricant composition according to at least one of the preceding claims further comprising additives, sealants and / or solid lubricants. [15] Lubricant composition according to at least one of the preceding claims comprising 50 to 90 wt.% water, in particular 50 to 80 wt.% water. [16] Gliding film - a first wax A, wherein the first wax is selected from one or more members of the group consisting of: Polypropylene wax, modified polypropylene wax, ethylene-acrylic acid copolymer and ethylene-methacrylic acid copolymer; - a second wax B, wherein the second wax is selected from one or more members of the group consisting of: Carnauba wax, sugar cane wax, ethylene bis-stearamide wax, polyethylene wax, modified polyethylene wax, Fischer-Tropsch wax, modified Fischer-Tropsch wax, paraffin wax, and modified paraffin wax; and - microspherical inorganic particles C as solid bodies; where - the weight ratio of A : B is between 10 : 1 and 1 : 1; and - the weight ratio of (A + B) : C is from 5 : 1 to 1 : 3; wherein the sum of first wax A, second wax B and microspherical inorganic particles C together constitutes at least 20 wt.%, preferably at least 35 wt.% of the lubricating film. [17] Lubricating film according to claim 16, wherein the first wax A is selected from one or more members of the group: Polypropylene wax and modified polypropylene wax; and / or The second wax B is selected from one or more members of the group: Polyethylene wax, Fischer-Tropsch wax, modified polyethylene wax and modified Fischer-Tropsch wax. [18] Lubricating film according to claim 16 or 17, wherein the first wax A or the second wax B or both have a particle diameter of d 90 smaller than 30 µm preferred d 90 exhibit dimensions smaller than 10 µm. [19] Lubricating film according to at least one of claims 16 to 18, wherein the microspherical inorganic particles C are oxide inorganic materials, in particular selected from one or more members of the group consisting of: Alkali aluminosilicates, aluminum oxides, borosilicate glasses, clay minerals and products, which are obtained by calcining clay minerals. [20] Lubricating film according to at least one of claims 16 to 19, wherein the microspherical oxide particles C have a particle diameter of: - d 90 smaller than 30 µm, preferably d 90 smaller than 25 µm, especially preferred d 90 smaller than 20 µm; and / or - dso smaller than 20 µm, preferably d 50smaller than 12 µm, especially preferred d 50 less than 8 µm. [21] Lubricating film according to at least one of claims 16 to 20, wherein the microspherical oxide particles C have a particle diameter of: - d 90 greater than 2 µm, especially greater than 3 µm; and / or - d 50 greater than 1 µm, especially greater than 1.5 µm. [22] Lubricating film according to at least one of claims 16 to 21, wherein the microspherical particles C have a sphericity greater than 0.9, in particular greater than 0.

95. [23] Lubricating film according to at least one of claims 16 to 22, wherein the lubricating film comprises, in relation to the base composition consisting of A, B and C, each: - the first wax A of 15 to 65 parts by weight (Wt), preferably of 20 to 53 Wt; - the second wax B from 3 to 40 GT, preferably from 5 to 35 GT; - the microspherical oxide particles C of 10 to 70 GT, preferably 15 to 55 GT; wherein the sum of A + B + C = 100 GT. [24] Lubricating film according to at least one of claims 16 to 23, each comprising a further binder, wherein the sum of A, B and C is from 25 to 99.9 GT, preferably from 45 to 85 GT; and the binder comprises 0.1 to 75 parts by weight, preferably 15 to 55 parts by weight, based on the solids content of the binder; and where the sum of A + B + C + solids of the binder = 100 GT. [25] Lubricating film according to at least one of claims 16 to 24, each comprising: no binder the first wax A of 12 to 65 wt.%, preferably 17 to 53 wt.%; the second wax B in 2 to 40 wt.%, preferably in 4 to 35 wt.%; the microspherical oxide particles C of 8 to 70 wt.%, preferably of 12 to 55 wt.%; in relation to the total weight of the lubricating film. [26] Lubricating film according to at least one of claims 16 to 25, each further comprising a binder, comprising: the components A + B + C in amounts of 20 to 99.9 wt.%, preferably 35 to 85 wt.%, the binder in a concentration of 0.1 to 75 wt.%, preferably 12 to 55 wt.%; in relation to the total weight of the lubricating film. [27] Lubricating film according to at least one of claims 16 to 26 further comprising additives, sealants and / or solid lubricants. [28] Lubricant concentrate comprising 35 to 70 wt.% water and in terms of solids content: A first wax A in the form of wax particles of 12 to 65 wt.%; preferably 17 to 53 wt.%; a second wax B in the form of wax particles of 2 to 40 wt.%; and preferably of 4 to 35 wt.%; microspherical oxide particles C as solid particles of 8 to 65 wt.% and preferably of 12 to 50 wt.%, where the first wax A is selected from one or more members of the group consisting of: Polypropylene wax, modified polypropylene wax, ethylene-acrylic acid copolymer and ethylene-methacrylic acid copolymer; where the second wax B is selected from one or more members of the group consisting of: Carnauba wax, sugar cane wax, ethylene bis-stearamide wax, polyethylene wax, modified polyethylene wax, Fischer-Tropsch wax, modified Fischer-Tropsch wax, paraffin wax and modified paraffin wax, where - the weight ratio of A : B is between 10 : 1 and 1 : 1; and - the weight ratio of (A + B) : C is from 5 : 1 to 1 : 3.

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