Aqueous coating compositions and their use

Abstract

To provide a coating composition which permits precise setting of coefficients of friction of components, particularly fastening components, such as particularly screws, nuts, bolts or rivets, and which moreover does not require the use of PTFE and preferably dispenses entirely with fluorinated polymers.SOLUTION: The invention relates to a coating composition for producing a coating with an adjustable coefficient of friction.

Description

[Technical Field]

[0001] The present invention relates to the technical field of coatings, particularly coatings for large quantities of materials. In particular, the present invention relates to an aqueous coating composition for producing a coating having an adjustable coefficient of friction. Furthermore, the present invention relates to a method for producing a coating having an adjustable coefficient of friction and to the use of an aqueous coating composition for producing a coating having an adjustable coefficient of friction. Finally, the present invention relates to a coated substrate. [Background technology]

[0002] Fasteners, especially small parts such as bolts, nuts, and screws, used to mechanically fasten components, particularly metal parts, need to have a specific, repeatable coefficient of friction so that they can be manufactured industrially. The coefficient of friction μ represents the ratio of the normal force to the frictional force, and a higher coefficient of friction indicates a higher frictional force. A higher frictional force reduces the energy transferred to the elastic or plastic elongation of the screw during the tightening process, resulting in a decrease in the so-called preload force. The preload force is typically specified to ensure the reliable performance of bolted joints, which is why the coefficient of friction needs to move within a specified window. This is particularly important in the case of fastening materials, such as bolts, screws, nuts, or even rivets, as these are used to secure parts mechanically. On the one hand, friction needs to be high enough to prevent unintended loosening of the compound, but at the same time, it needs to be low enough to allow for a perfect bond between materials.

[0003] Furthermore, the coefficient of friction needs to be set as constant as possible, especially to enable industrial machining using robots, for example, for screws with a specified torque or bolt rivets with a constant force. For this reason, small fasteners are often coated with a specific coating composition, in the form of a topcoat, intended to influence and set the sliding and frictional properties of the part in a desirable manner. The desirable sliding and frictional properties of screws or bolts are usually measured in accordance with DIN EN ISO 16047:2013-01, in which the German Association of the Automotive Industry (VDA) specifically defines a friction coefficient μ window of 0.09 to 0.16 for screws.

[0004] To achieve a desired coefficient of friction, certain topcoat compositions typically contain fluorinated plastic particles, particularly those based on polyfluorotetraethylene (PTFE) or polyvinylidene fluoride (PVDF). However, the use of fully fluorinated or partially fluorinated compounds has several serious drawbacks: on the one hand, fluorinated polymers are relatively expensive, and on the other hand, they should be avoided from an environmental protection standpoint. During the production of fluorinated compounds, particularly PTFE, a considerable amount of perfluorooctanoic acid (PFOA) is usually produced or used for the manufacture of these compounds. Perfluorooctanoic acid is practically non-degradable in nature, accumulates in living organisms, and is particularly liver-damaging, reproductive-toxic, and carcinogenic. Therefore, the production of perfluorooctanoic acid and its precursor compounds has been banned in the European Union since July 4, 2020, with few exceptions. PTFE can be purified with respect to PFOA, and thus PFOA-free PTFE can be used, but this is energy-intensive and makes the extraction of raw materials more expensive. PTFE itself is difficult to disperse in aqueous media, is not degradable in nature, and is a so-called persistent material; therefore, it should be replaced with more environmentally friendly raw materials. Furthermore, the manufacture or use of PTFE also produces polyfluorinated by-products and degradation products, which should not be released into the environment if possible.

[0005] For this reason, efforts are being made to replace polyfluorinated plastics with other materials whenever possible. However, this replacement is often not easy because polyfluorinated or fully fluorinated plastics have unique and sometimes outstanding properties, particularly with respect to their hydrophobic wetting or non-wetting properties, their resistance to chemical and physical properties, and their excellent sliding properties. One problem that arises particularly in screwed joints is heat dissipation behavior, as the sliding properties of many plastics change with increasing temperature. In particular, the sliding properties of many plastics improve when heated. However, this is undesirable for screwed joints because it increases the risk of unintended joint loosening. Totally fluorinated plastics, especially PTFE and PVDE, do not exhibit this problematic behavior or only to a limited extent, and therefore they remain the materials of choice for setting the sliding or frictional properties of fasteners in the desired manner. PTFE is particularly characterized by its high melting point, which allows its frictional behavior to be optimized over a higher temperature range.

[0006] Another problem that arises particularly when screws are tightened at high speeds is the so-called stick-slip effect, also known as jerk slip. In this case, the screw does not move smoothly during tightening, but instead begins to stick and slip. This results in uncertainty in torque on the one hand, uncertainty in preload on the other, and can then lead to the risk of hidden failures during operation. Therefore, the stick-slip effect should be avoided as much as possible, which is why the sliding and sticking properties of a bolt need to be set particularly accurately and uniformly. To date, the stick-slip effect can be prevented to the greatest extent by using a topcoat containing a fluorinated polymer. However, one drawback of fluorinated polymers is that, due to their hydrophobicity, they should be preferentially used in solvent-based systems. However, for reasons of environmental protection and occupational safety, aqueous systems are increasingly preferred. To date, the situation in this field lacks an aqueous coating system that can successfully achieve the desired friction coefficient, particularly for small fastening components, without using PTFE, and preferably without using fluorinated polymers at all, while meeting the requirements for a narrowly defined friction coefficient window, heat dissipation, and stick-slip behavior. [Overview of the project]

[0007] Therefore, an object of the present invention is to provide a coating composition that enables precise setting of the coefficient of friction of parts, particularly fastening parts, such as screws, nuts, bolts, or rivets, and furthermore, does not require the use of PTFE, and preferably does not require any fluorinated polymers at all. Furthermore, an object of the present invention is to provide a coating system that contains at least little organic solvent, preferably no organic solvent at all. A further object of the present invention is to provide a coating system that largely prevents the stick-slip effect. Accordingly, the content of the present invention according to a first aspect of the present invention is the aqueous coating composition described in claim 1, and furthermore, an advantageous embodiment of this aspect of the present invention is the content of the related dependent claims. Furthermore, another aspect of the present invention according to a second aspect of the present invention is the use of the coating composition described in claim 15. Furthermore, a further aspect of the present invention according to a third aspect of the present invention is a method for producing the coating described in claim 16, and further, an advantageous embodiment of this aspect of the present invention is the subject matter of the related dependent claims. Finally, a further aspect of the present invention according to a fourth aspect of the present invention is the metal substrate described in claim 18, and furthermore, an advantageous embodiment of this aspect of the present invention is the subject matter of the related dependent claims.

[0008] Needless to say, certain characteristics, features, embodiments, and advantages are described below in relation to only one aspect of the present invention for the purpose of avoiding unnecessary repetition, and will naturally apply appropriately to other aspects of the present invention without requiring explicit reference. Furthermore, it applies that all values ​​or parameter data described below can, in principle, be measured, or can be measured by standardized or clearly stated measurement methods or measurement methods well known to those skilled in the art. Furthermore, it goes without saying that all percentages related to mass or quantity are selected by those skilled in the art such that they add up to 100%. Under these stated conditions, the present invention will be described in more detail below. [Modes for carrying out the invention]

[0009] Therefore, the present invention First The present invention, according to its embodiments, provides an aqueous coating composition for producing a coating having an adjustable coefficient of friction, particularly a topcoat, (a) an organic binder comprising a copolymer of at least one unsaturated hydrocarbon and at least one unsaturated carboxylic acid, and (b) A coating composition comprising a lubricant. The applicant has surprisingly found that when a coating composition is used that includes an organic binder comprising at least one unsaturated hydrocarbon, particularly a copolymer of an olefin and at least one unsaturated carboxylic acid, and a lubricant, a topcoat with excellent sliding and frictional properties can be obtained. Such coating compositions can be readily prepared in an aqueous medium and do not even have to contain PTFE. Preferably, they do not even contain any fluorinated polymers. Therefore, the present invention provides that in a system that does not contain both a solvent and a fluorinated polymer, particularly PTFE, a top coat that can set the coefficient of friction to a value required for industrial production can be easily utilized. Therefore, the coating composition of the present invention is superior from both environmental and labor safety perspectives compared to the conventional fluoropolymer-containing solvent-based systems known to date.

[0010] Preferably, the organic binder already has certain slip characteristics. These slip characteristics of the binder are achieved particularly by segments constructed from polymerized unsaturated hydrocarbons of the copolymer, particularly polymerized olefins. The polar groups of carboxylic acids keep the polymer water-soluble or at least water-dispersible despite having hydrophobic regions. When a lubricant is added to the organic binder, it has been shown that the slip characteristics are further greatly improved, and the coefficient of friction can be stably set, particularly even at elevated temperatures. In light of the present invention, a lubricant is understood to be a chemical substance, or a mixture of substances, that changes the tribological properties of the coating, particularly reducing friction. In light of the present invention, the lubricant can exist in the form of a liquid or a solid, and it is preferred to use a solid lubricant.

[0011] As already mentioned, in light of industrial production, particularly screw tightening by robots, it is essential that the slip characteristics or the coefficient of friction of the coated fasteners, particularly screws, always take equivalent values in a reproducible manner. For this reason, VDA guideline 235-101 defines a so-called coefficient of friction window within which the coefficient of friction μ of fastening means, particularly bolts, nuts, and screws, can be located. This coefficient of friction window extends over the range of the coefficient of friction μ from 0.09 to 0.16. The coefficient of friction is measured in accordance with DIN EN ISO 16047:2013-01. Other coefficient of friction windows are defined and, if desired, can also be met by the approach of the present invention described.

[0012] According to the present invention, it is preferred that the surface or the coated substrate coated with the coating composition of the present invention has a coefficient of friction μ measured in accordance with DIN EN ISO 16047:2013-01 in the range of 0.09 to 0.16. In the case of screws, the coefficient of friction can be measured both on the thread and on the flat surface, especially on the head of the screw. This double measurement is necessary because workpieces, especially screw parts, have different coefficients of friction between the thread and the flat coated surface, for example the head of the screw. For example, a screw designed as an internal support has a higher coefficient of friction on the thread and as a result poorer sliding properties than the head of the screw on a nut or a washer of the screw. When the screw is an outer carrier, the coefficient of friction is higher on the head than on the thread. Since the measurement of the coefficient of friction of the entire workpiece includes the measurement of the coefficients of friction of both areas (thread and flat surface), workpieces coated with a coating without a lubricant often have an undesirably high coefficient of friction. However, according to the present invention, the use of a lubricant can be omitted. Within the scope of the present invention, for threaded parts, such as screws, it is preferably provided that the coefficients of friction of both the thread and the flat surface are located within the above-mentioned coefficient of friction window of the coefficient of friction μ of 0.09 to 0.16.

[0013] Since the test rules described in DIN EN ISO 16047:2013-01 apply to a single tightening, the preparation of the test for multiple tightenings is further specified in a test sheet according to VDA 235-203. Within the scope of the present invention, it is preferably further provided that the above-mentioned coefficient of friction window for the coefficient of friction μ of 0.09 to 0.16 is also met in the case of multiple tightenings of both the thread and the flat surface. Furthermore, the thermal loosening behavior of workpieces, especially fasteners such as screws or bolts, is also important, particularly when they are incorporated into assemblies, such as near an engine. For this reason, VDA test sheet 235-203 specifies preparation for testing under a temperature load of 150°C, where the friction coefficient window μ of 0.06 must not undershoot. Within the scope of the present invention, it is therefore preferable that a workpiece coated with the coating composition of the present invention has a coefficient of friction μ in the range of 0.09 to 0.16 at 150°C according to VDA test sheet 235-203. This coefficient of friction window is preferably satisfied for both the total coefficient of friction and, in the case of a threaded workpiece, for both the threads and the flat surface.

[0014] In light of the present invention, unsaturated hydrocarbons are understood as preferably nonpolar organic compounds having at least one unsaturated bond, particularly at least one carbon-carbon double bond or carbon-carbon triple bond. Aromatic and heteroaromatic compounds having alkene or alkyne side chains, particularly vinyl and / or alkenyl groups, are also included, but unsaturated hydrocarbons are mainly alkenes and alkynes, particularly compounds having vinyl and / or alkenyl groups. Furthermore, hydrocarbons may also be substituted with, for example, halides and alcohol, amine or thiol functional groups. However, preferredly, hydrocarbons are unsubstituted hydrocarbons, i.e., alkenes and alkynes or mixtures thereof. In light of the present invention, an unsaturated carboxylic acid means a carboxylic acid having a carbon double bond or a carbon triple bond. In addition to an acidic group, a carboxylic acid may have further functional groups, particularly alcohol, thiol, amine, and ether functional groups. The carboxylic acid also includes, in particular, derivatives of carboxylic acids, especially their esters and amides. In light of the present invention, it is even more preferable that the copolymer comprising at least one unsaturated hydrocarbon and at least one unsaturated carboxylic acid is a block copolymer. In light of this, it is even more preferable that the block copolymer has blocks of segments of unsaturated hydrocarbon. Unsaturated hydrocarbons contribute in particular to the fact that the binder of the coating composition, especially the topcoat composition, already has excellent slip properties and allows for the setting of the coefficient of friction in the desired manner.

[0015] Typically, in light of the present invention, it is provided that the unsaturated hydrocarbon is selected from the group consisting of aliphatic hydrocarbons having a vinyl group, aromatic hydrocarbons having a vinyl group, aliphatic hydrocarbons having an alkynyl group, aromatic hydrocarbons having an alkynyl group, and mixtures thereof. The results obtained are particularly favorable when the unsaturated hydrocarbon is selected from the group consisting of aliphatic hydrocarbons having a vinyl group, aromatic hydrocarbons having a vinyl group, and mixtures thereof. It is more preferable that the unsaturated hydrocarbon is an aliphatic hydrocarbon having a vinyl group. The unsaturated hydrocarbon is preferably an alkene and / or alkyne, and preferably an alkene, as described above. By using hydrocarbons having vinyl groups or alkenes, it becomes possible to create non-polar segments in the copolymer that impart slip properties to the binder or coating, thereby facilitating the adjustment of specific friction coefficients.

[0016] Within the scope of the present invention, the unsaturated hydrocarbon is an aliphatic and / or aromatic C2-C having an alkynyl group. 20 Compounds, aliphatic and / or aromatic C2-C having a vinyl group 20 Compounds and mixtures thereof, particularly aliphatic and / or aromatic C2-C compounds having an alkynyl group. 12 Compounds, aliphatic and / or aromatic C2-C having a vinyl group 12 Compounds and mixtures thereof, preferably aliphatic and / or aromatic C2-C having an alkynyl group. 10 Compounds, aliphatic and / or aromatic C2-C having a vinyl group 10Compounds and their mixtures, preferentially aliphatic and / or aromatic C2-C8 compounds having an alkynyl group, aliphatic and / or aromatic C2-C8 compounds having a vinyl group and their mixtures, particularly preferentially aliphatic C2-C6 compounds having a vinyl group, more preferentially aliphatic C2-C4 alkenes having a vinyl group, particularly preferably C2 and C3 alkenes, give particularly good results when selected. It is often shown that the unsaturated hydrocarbon is selected from the group of aliphatic C2-C4 alkenes having a vinyl group. In light of this, it is more preferable that the unsaturated hydrocarbon is selected from C2 and C3 alkenes and their mixtures. In light of the present invention, it is even more preferable that C2 alkene, i.e., ethene, is used.

[0017] In light of the present invention, it is equally preferable that the unsaturated hydrocarbon is selected from the group of styrene, 1-hexene, 1-pentyne, 1-butyne, 2-butyne, propyne, ethyne, 1-hexene, 1-pentene, 1-butene, 2-butene, propene, ethene and their mixtures. Preferentially, the unsaturated hydrocarbon is selected from the group of 1-hexene, 1-pentene, 1-butene, 2-butene, propene, ethene, 1-hexene, 1-pentene, 1-butene, 2-butene, propene, ethene and their mixtures. Particularly good results are obtained when the unsaturated hydrocarbon is selected from styrene, 1-butene, 1-propene, ethene and their mixtures, particularly 1-butene, 1-propene, ethene and their mixtures, preferably propene, ethene and their mixtures. In light of the present invention, it is even more preferable that the unsaturated hydrocarbon is ethene.

[0018] As far as unsaturated carboxylic acids are concerned, they can be selected from a wide range of compounds. However, it has been shown that it is advantageous when the unsaturated carboxylic acid is selected from alkene acids. The unsaturated carboxylic acid is C2-C 20 alkene acid, particularly C2-C 12 alkene acid, preferably C2-C 10Alkenic acids, preferably C2-C4 alkenic acids, especially preferably C2-C3 alkenic acids, and their esters and amides are selected, and in this case, particularly good results are obtained. However, preferably, the unsaturated carboxylic acid is intended to be used as a free acid. In light of the present invention, an unsaturated carboxylic acid is acrylic acid, acrylic acid and C1-C 10 Ester with alcohol, methacrylic acid, methacrylic acid and C1-C 10 It is often shown that the unsaturated carboxylic acid is selected from the group consisting of esters with alcohols, fumaric acid, maleic acid, and mixtures thereof. In light of this, the unsaturated carboxylic acid is selected from acrylic acid, acrylic acid and C1-C 10 Ethers with alcohols, methacrylic acid, and methacrylic acid with C1-C 10 Particularly good results are obtained when selected from the group consisting of esters with alcohols and mixtures thereof.

[0019] In light of the present invention, it is even more preferable that the unsaturated carboxylic acid is selected from the group consisting of acrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, isobutyl acrylate, 2-ethylhexyl acrylate, methacrylic acid, methyl methacrylate, ethyl methacrylate, butyl methacrylate, isobutyl methacrylate, and hexyl methacrylate. In light of this, it is particularly evident that the unsaturated carboxylic acid is selected from the group consisting of acrylic acid, methyl acrylate, ethyl acrylate, methacrylic acid, methyl methacrylate, and ethyl methacrylate, and is preferably acrylic acid and methacrylic acid.

[0020] As far as the molecular weight of the copolymer is concerned, this can naturally vary over a wide range. However, copolymers are often shown to have a weight-average molecular weight Mw in the range of 2,000 to 250,000 g / mol, particularly 5,000 to 200,000 g / mol, preferably 10,000 to 150,000 g / mol, and preferentially 15,000 to 100,000 g / mol. In light of the present invention, the molecular weight of the polymer compounds refers to the weight-average molecular weight Mw, obtained by weighting the masses of the individual polymer compounds by their mass fractions. Molecular weight or molecular weight distribution can be measured by various standardized procedures and methods, such as light scattering, rheology, mass spectrometry, and permeation chromatography. However, the methods used to measure molecular weight distribution are well known to those skilled in the art and do not require further explanation. For example, the molecular weight of the polymer used can be measured, in particular by the GPC method, using polymethyl methacrylate or polystyrene as a standard, based on DIN 55672.

[0021] The coating composition may contain an organic binder in almost any amount. However, it is often shown that the coating composition contains an organic binder in an amount of 2 to 70% by mass, particularly 5 to 60% by mass, preferably 10 to 50% by mass, and more preferably 10 to 40% by mass, based on the coating composition. As already mentioned, the coating composition includes a lubricant. Preferably, the lubricant is selected from the group consisting of organic lubricants, inorganic lubricants, and mixtures thereof. However, in light of the present invention, particularly good results are obtained when the lubricant is an organic lubricant.

[0022] The lubricants used in light of the present invention are typically in particulate form. In this respect, the lubricants typically have an absolute particle size in the range of micrometers. In light of the present invention, particularly good results are obtained when the lubricant is selected from the group consisting of wax, graphene, graphite, boron nitride, molybdenum disulfide, plastic particles, especially polyether ketone (PEK), polyetherether ketone (PEEK), polyphenylene sulfide (PPS), polyethersulfone (PES), polyetherimide (PEI), polyamideimide (PAI) and mixtures thereof, finely powdered sulfur and mixtures thereof. Preferably, the lubricant is selected from the group consisting of wax, graphene, graphite, boron nitride, molybdenum disulfide and mixtures thereof. In light of the present invention, particularly good results are obtained when the lubricant is wax. In light of the present invention, waxes are generally understood as natural or artificially obtained substances that are typically kneadable at 20°C, ranging from solid to brittle and hard, from coarse to fine crystalline, translucent to opaque but not glassy, ​​and melt without decomposition above 40°C. Slightly above their melting point, waxes typically become relatively low in viscosity and non-stringy. Waxes differ from similar synthetic or natural products mainly in that they typically melt to a low-viscosity state between about 50 and 90°C, exceptionally up to about 200°C, and practically do not contain ash-forming components. Waxes form pastes or gels and typically burn in a flame, producing soot. Based on their origin, waxes are classified into three groups: natural waxes, semi-synthetic waxes, and synthetic waxes. Natural waxes consist particularly of plant waxes, such as candelilla wax, carnauba wax, or montan wax; animal waxes, such as beeswax, lanolin, and brushing lipids; mineral waxes, such as ceresin and ozokerite; and petrochemical waxes, particularly petrolatum, kerosene wax, and microwax. Semi-synthetic waxes are particularly hard waxes, such as montan ester wax and hydrogenated jojoba wax. Synthetic waxes are, for example, polyalkylene wax or polyethylene glycol wax.

[0023] When the lubricant is a wax, it is often indicated that the wax is selected from the group consisting of natural waxes, semi-synthetic waxes, synthetic waxes, and mixtures thereof. Preferably, the wax is a synthetic wax. Similarly, in light of the present invention, it is preferable that the wax is selected from the group consisting of beeswax, carnauba wax, montan wax, modified montan wax, amide wax, polypropylene wax, polyethylene wax, HDPE wax (high-density polyethylene wax), oxidized HDPE wax, ethylene vinyl acetate wax, polyethylene glycol wax, polyester wax, Fischer-Tropsch wax, and mixtures thereof, preferably polypropylene wax, polyethylene wax, HDPE wax, oxidized HDPE wax, ethylene vinyl acetate wax, polyethylene glycol wax, polyester wax, Fischer-Tropsch wax, and mixtures thereof.

[0024] In light of this, particularly good results are obtained when the wax is selected from the group consisting of polypropylene wax, polyethylene wax, HDPE wax, oxidized HDPE wax, Fischer-Tropsch wax, and mixtures thereof. More preferably, in light of the present invention, the wax is polyethylene wax (PE wax). Waxes, particularly synthetic waxes, preferably polyethylene waxes, can be used as lubricants to set the sliding and frictional properties of coating compositions to excellent levels. In particular, combinations of organic binders and wax-based lubricants exhibit excellent and consistent coefficients of friction, especially under multiple loads and thermal stress.

[0025] Here, with respect to the amount of lubricant contained in the coating composition, this can vary over a wide range. However, it has been found that the coating composition is preferable when it contains lubricant in an amount of 0.1 to 10% by mass, particularly 0.3 to 8% by mass, preferably 0.5 to 5% by mass, and preferably 0.8 to 4% by mass, based on the coating composition. In light of the present invention, it is advantageous that the coating composition does not contain fluorine-containing compounds, and in particular does not contain organofluorine-containing compounds. In light of the present invention, it is even more preferable that the coating composition does not contain fluorinated polymer particles, and in particular does not contain PTFE and PVDF. A significant advantage of the present invention is the ability to provide a coating composition having a selectively adjustable coefficient of friction without the use of fluorinated polymer particles, which is of concern. In particular, within the scope of the present invention, it is possible to provide a coating composition having excellent slip and friction properties that completely does not contain the use of fluorinated organic compounds. Within the scope of the present invention, it can be further provided that the coating composition comprises at least one thickener and / or rheological additive.

[0026] The thickeners and / or rheological additives, in particular, serve to set the viscosity and flow, or even the layer thickness to which the composition of the present invention can be applied to the substrate. If the coating composition contains a thickener and / or rheological additive, the coating composition typically contains the thickener and / or rheological additive in an amount of 0.01 to 5% by mass, particularly 0.05 to 3% by mass, preferably 0.1 to 2% by mass, based on the coating composition. Thickening agents and / or rheological additives can be selected from a variety of suitable compounds and classes. However, it is often shown that thickening agents and / or rheological additives are selected from the group consisting of ethylcellulose, silicic acid, and mixtures thereof. More preferably, the thickening agent and / or rheological additive is silicic acid, and in particular fumed silica.

[0027] According to another preferred embodiment of the present invention, the coating composition is (a) an organic binder comprising a copolymer of at least one unsaturated hydrocarbon and at least one unsaturated carboxylic acid, (b) Lubricants, and (c) Contains thickeners and / or rheological additives. In this preferred embodiment of the present invention, all the advantages, properties and specific features described above are appropriately applied in light of further embodiments and properties of the coating composition of the present invention. Furthermore, in light of the present invention, it is possible to provide that the coating composition contains platelet-shaped particles.

[0028] In light of the present invention, platelet-shaped particles are often also called flake-shaped particles and are understood as particles whose thickness is considerably smaller than their length and width, that is, whose extent in one spatial direction is considerably smaller than that in the other two spatial directions. Typically, the aspect ratio, i.e., the ratio of the particle's length or width to its thickness, is in the range of 2:1 to 100:1, particularly 4:1 to 50:1, preferably 5:1 to 20:1, and more preferably 8:1 to 15:1. Platelet-shaped particles are preferably selected from the group consisting of metal flakes, glass flakes, layered silicates, and mixtures thereof. Layered silicates are preferably selected from the group consisting of mica, talc, bentonite, kaolin, and mixtures thereof. In light of this, metal flakes are preferably selected from the group consisting of aluminum flakes, zinc flakes, copper flakes, and mixtures thereof. Preferably, the platelet-shaped particles are metal flakes selected from the group consisting of aluminum flakes, zinc flakes, copper flakes, and mixtures thereof. It is more preferable that the platelet-shaped particles are aluminum flakes. If the coating composition contains platelet-shaped particles, the coating composition typically contains platelet-shaped particles in an amount of 0.3 to 8% by mass, preferably 0.5 to 5% by mass, and more preferably 0.8 to 4% by mass, based on the coating composition. In light of this, particularly good results are obtained when the coating composition contains a total amount of lubricant and platelet-shaped particles in the range of 0.5 to 20% by mass, especially 1 to 18% by mass, preferably 1.5 to 15% by mass, and preferably 2 to 12% by mass, based on the coating composition.

[0029] By further incorporating platelet-shaped particles into a coating composition, it becomes possible to precisely set the coefficient of friction and sliding properties of the coated substrate, and in particular, to more effectively avoid the stick-slip effect. Furthermore, the use of platelet-shaped particles also makes it possible to dry or cure the coating composition at high temperatures without observing an increase in the coefficient of friction. This is surprising, as topcoats containing lubricants, especially waxes, have a higher coefficient of friction after exposure to temperature, particularly after drying at high temperatures. This is due in part to the fact that lubricants, especially waxes, enter the gas phase or decompose thermally during the drying process. Surprisingly, topcoats containing platelet-shaped particles in addition to lubricants do not exhibit this increase in the coefficient of friction. Although not bound by theory, this is probably due to the fact that platelet-shaped particles act as a diffusion barrier, on the one hand preventing oxygen from penetrating the coating, thereby slowing the decomposition of the lubricant, and on the other hand preventing the lubricant from entering the gas phase when evaporable or sublimable lubricants are used. Particularly good results are obtained when the mass ratio of platelet-shaped particles to lubricant is 1:0.8 to 1:1.8, especially 1:1 to 1:1.6, and preferably 1:1.1 to 1:1.4, based on the mass of platelet-shaped particles and lubricant in the coating composition.

[0030] According to a preferred embodiment of the present invention, the coating composition, (a) an organic binder comprising a copolymer of at least one unsaturated hydrocarbon and at least one unsaturated carboxylic acid, (b) Lubricants, (c) Thickeners and / or rheological additives, (d) Contains platelet-shaped particles. In this preferred embodiment of the present invention, all the advantages, properties and specific features described above are appropriately applied in light of further embodiments and properties of the coating composition of the present invention. Furthermore, it can be provided that the coating composition contains at least one additional additive.

[0031] If the coating composition contains further additives, the coating composition contains the further additives in an amount of 0.01 to 5% by mass, particularly 0.05 to 3% by mass, preferably 0.1 to 2% by mass, based on the coating composition. In light of this, particularly good results can be obtained when additional additives are selected from the group consisting of wetting agents, preservatives, stabilizers, acids and / or bases, defoaming agents, film-forming agents, leveling agents, UV absorbers, fillers, pH stabilizers, and pH adjusters.

[0032] According to a preferred embodiment of the present invention, therefore, (a) an organic binder comprising a copolymer of at least one unsaturated hydrocarbon and at least one unsaturated carboxylic acid, (b) Lubricants, (c) Thickeners and / or rheological additives, (d) Platelet-shaped particles, (e) A coating composition containing further additives is provided. All the advantages, characteristics and specific features described above apply appropriately to this particular embodiment of the present invention in light of further embodiments and characteristics of the present invention.

[0033] A preferred embodiment of the present invention provides a coating composition further comprising an inorganic binder. The addition of an inorganic binder improves, in particular, the abrasion resistance and mechanical resistance of the coating. Furthermore, the use of inorganic binders is also commercially desirable because they are often inexpensive to manufacture or obtain on a large industrial scale. When the coating composition comprises an inorganic binder, the inorganic binder is typically a silicon-containing binder. Preferably, the inorganic binder is selected from silane, silane hydrolysate, silicate, polysiliconate, and mixtures thereof. In light of this, particularly good results are obtained when the inorganic binder is selected from the group consisting of silanes, especially trialkoxysilanes and tetraalkoxysilanes, preferably vinylsilanes, aminesilanes, phenoxysilanes and / or epoxysilanes, tetraethyl orthosilicate (TEOS), tetramethyl orthosilicate (TMOS), silane hydrolysates, colloidal silicic acid, water glass or silicates, especially lithium water glass, sodium water glass, potassium water glass, and mixtures thereof. In particular, the silanes that can be preferably used are those described below in the production of silane-modified silicates.

[0034] According to preferred embodiments of the present invention, the inorganic binder does not particularly contain lithium compounds. Within the scope of the present invention, particularly good coating and slip properties can be obtained even when the normally preferred lithium polysilicate (lithium water glass) is not used. This is a noteworthy advantage of the present invention, especially given that the increasing use of lithium-ion batteries and lithium-ion storage batteries in the automotive sector is expected to lead to a rise in the demand for lithium and the subsequent price of lithium. Preferably, the inorganic binder is selected from the group consisting of silanes, particularly trialkoxysilanes and tetraalkoxysilanes, preferably vinylsilanes, aminesilanes, phenoxysilanes and / or epoxysilanes, tetraethyl orthosilicate (TEOS), tetramethyl orthosilicate (TMOS), silane hydrolysates, colloidal silicic acid (silica sol), sodium aqueous glass, potassium aqueous glass, and mixtures thereof. More preferably, the inorganic binder is selected from the group consisting of sodium aqueous glass, potassium aqueous glass, and mixtures thereof.

[0035] According to a preferred embodiment of the present invention, the inorganic binder comprises or consists of a mixture of water glass and / or colloidal silicic acid and silane hydrolysate and / or silane. Preferably, the inorganic binder comprises a mixture of water glass and / or colloidal silicic acid and silane hydrolysate and / or silane. These mixtures also do not exhibit carbonation at alkaline pH values. According to this embodiment, it is preferable that the organic binder contains water glass and / or colloidal silicic acid in a mass ratio with silane hydrolysate and / or silane in the range of 15:1 to 1:2, particularly 1:1 to 1:1.5, preferably 5:1 to 1:1, and more preferably 4:1 to 1:1. Similarly, this embodiment clearly shows that the inorganic binder is set to a pH of less than 11, particularly less than 9, and preferably less than 8.5, especially before mixing with the organic binder. Preferably, the inorganic binder is set to a pH value of less than 8, particularly in the range of pH 5 to pH 7.5, especially before mixing with the organic binder.

[0036] In mixtures of water glass and / or colloidal silica and silane hydrolysates and / or silanes, particularly weak and minimal carbonation, i.e., absorption of carbon dioxide from the air and subsequent formation of carbonates, is observed, especially at pH values ​​in the alkaline range. Carbonation, particularly in the case of topcoats, leads to undesirable impairment of surface properties, especially appearance, by clouding the topcoat. Subsequently, the coating often appears dusty, which is undesirable. Another advantage of the described mixture is that the pH of the inorganic binder and / or coating composition can be set to the acidic range without precipitating silicates or silicates. In this regard, particularly good results are obtained when the inorganic binder is a silane-modified silicate compound or silane-modified water glass. Silane-modified silicate compounds or silane-modified water glass are usually obtained by at least partially hydrolyzing and / or condensing at least one silane in the presence of at least one silicate at a pH of 8 or higher. Similarly, when a silane-modified silicate compound or silane-modified water glass is used, carbonation is not observed, and the pH of the inorganic binder or coating composition can be set to a value of 7 or less without precipitating the silicate. In this case, the pH can be adjusted by adding an acid. In particular, since the absorption of carbon dioxide in the form of carbonate is considerably reduced in the acidic range, it is preferable to use a silane-modified silicate compound or silane-modified water glass in a neutral or acidic pH range.

[0037] Preferably, a method for producing a silane-modified silicate or silane-modified water glass is carried out such that silane is at least partially hydrolyzed in the presence of a silicate compound or water glass at a pH of 8 or higher, particularly greater than 11, to obtain a silane-modified silicate or water glass, and then an acid is added to set the pH to a value less than 8.5, particularly less than 8, preferably in the range of 4 to 7.

[0038] During acidification, it is possible to set the pH value between 2 and 4, and this setting can be achieved and maintained without causing precipitation or aggregation of the silane-modified silicate compound or silane-modified water glass. Beneficial effects have already been observed only when the partial hydrolysis or condensation of silane occurs in an alkaline aqueous solution in the presence of a silicate. However, the hydrolysis or condensation of silane in the presence of a silicate to form silane-modified silicate compounds or silane-modified water glass is often carried out completely in an alkaline environment. The partial hydrolysis of silanes and silicates in alkaline aqueous solutions can be continued, if necessary, after acidification to pH 7 or below, until the hydrolysis is complete. According to this embodiment, the compounds described above, particularly lithium water glass, sodium water glass, potassium water glass, and mixtures thereof, preferably sodium water glass, potassium water glass, and mixtures thereof, are used as water glass or silicate.

[0039] For the production of silane-modified silicate compounds or water glass, epoxy-functional, phenoxy-functional, vinyl-functional, or amino-functional silanes are advantageously used. More preferably, silanes having at least one Si-C bond, i.e., a bond between a silicon atom and a carbon atom, are used. Different silanes can be used together in a mixture.Particularly suitable silanes are methacryloxymethyltrimethoxysilane, methacryloxymethyltriethoxysilane, 3-aminopropylmethyldimethoxysilane, 3-aminopropyltriethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, and 3-mercaptopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-cyclohexyl-3- Minopropyltrimethoxysilane, N-cyclohexylamino-methyltriethoxysilane, 3-aminopropyltriethoxysilane, 3-(2-aminomethylamino)propyltriethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, 3-aminopropyltrimethoxysilane, 3-ureidopropyltrimethoxysilane, vinyltrimethoxysilane, vinyldimethoxymethylsilane, vinyltriethoxysilane, vinyltriacetoxysilane, 3-methacrylate Dipropyltrimethoxysilane, methacryloxymethyl)methyldimethoxysilane, methacryloxymethyltrimethoxysilane, 3-methacryloxypropyltriacetoxysilane, N-methyl[3-(trimethoxysilyl)propyl]carbamate, N-trimethoxysilylmethyl-O-methylcarbamate, N-dimethoxy(methyl)silylmethyl-O-methylcarbamate, tris-[3-(trimethoxysilyl)propyl]-isocyanurate, 3-glycidoxypropyltrimethoxysilane These are 3-glycidoxypropyltriethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, trimethylethoxysilane, isooctyltrimethoxysilane, isooctyltriethoxysilane, hexadecyltrimethoxysilane, (cyclohexyl)methyldimethoxysilane, dicyclopentyldimethoxysilane, phenyltriethoxysilane, triacetoxyethylsilane, and 1,2-bis(triethoxysilyl)ethane.

[0040] In the production of silane-modified silicates, silane and silicate are advantageously used in mass ratios of 2:1 to 1:10, particularly 1:1 to 1:5, preferably 1:1 to 1:3, and more preferably 1:1 to 1:2. Silane can be used as a single compound or as a mixture of silanes, and the same applies to silicate. Further details of the production of silane-modified silicates or water glass can be found in WO2016 / 107791, the disclosure of which is fully incorporated into this invention.

[0041] If the coating composition contains an inorganic binder, the coating composition typically contains the inorganic binder in an amount of 1 to 30% by mass, particularly 2 to 25% by mass, preferably 3 to 20% by mass, and more preferably 5 to 15% by mass, based on the coating composition. When the coating composition contains an inorganic binder, it is often shown that the coating composition contains an organic binder in an amount of 1 to 40% by mass, particularly 2 to 30% by mass, preferably 3 to 25% by mass, and more preferably 5 to 20% by mass, based on the coating composition. By combining organic and inorganic binders, the best results can be obtained in accordance with the present invention. In light of the present invention, it is clearly shown that the coating composition contains a total amount of binders, i.e., the total amount of organic and inorganic binders, in an amount of 2 to 70% by mass, particularly 5 to 60% by mass, preferably 10 to 50% by mass, and preferably 15 to 40% by mass, based on the coating composition.

[0042] Therefore, a preferred coating composition is (a1) An organic binder comprising a copolymer of at least one olefin and at least one unsaturated carboxylic acid, (a2) Inorganic binders, and (b) Lubricant Includes. In this preferred embodiment of the present invention, all the specific characteristics, features, and advantages described herein are appropriately applicable in light of further embodiments and characteristics. According to a further preferred embodiment of the present invention, the coating composition is (a1) An organic binder comprising a copolymer of at least one olefin and at least one unsaturated carboxylic acid, (a2) Inorganic binder, (b) Lubricants, and (c) Thickeners and / or rheological additives Includes.

[0043] In this preferred embodiment of the present invention, all the specific characteristics, features, and advantages described herein are appropriately applicable in light of further embodiments and characteristics. According to a preferred embodiment of the present invention, therefore, (a1) An organic binder comprising a copolymer of at least one olefin and at least one unsaturated carboxylic acid, (a2) Inorganic binder, (b) Lubricants, (c) Thickeners and / or rheological additives, (d) Further additives A coating composition containing the following is provided. In this preferred embodiment of the present invention, all the advantages, properties and specific features described above are appropriately applied in light of further embodiments and properties of the coating composition of the present invention.

[0044] According to a preferred embodiment of the present invention, therefore, (a1) An organic binder comprising a copolymer of at least one olefin and at least one unsaturated carboxylic acid, (a2) Inorganic binder, (b) Lubricants, (c) Thickening agents and / or rheological additives, (d) Further additives, and (e) Platelet-shaped particles A coating composition containing the following is provided.

[0045] All the advantages, characteristics and specific features described above apply appropriately to this particular embodiment of the present invention in light of further embodiments and characteristics of the present invention. Furthermore, it can be provided that the coating composition includes a filler. If the coating composition contains a filler, the coating composition typically contains the filler in an amount of 0.5 to 50% by mass, particularly 1 to 40% by mass, preferably 5 to 35% by mass, and preferentially 10 to 30% by mass, based on the coating composition. Particularly good results are obtained when the filler is selected from calcium carbonate, barium sulfate, talc, and mixtures thereof.

[0046] According to a preferred embodiment of the present invention, therefore, (a1) An organic binder comprising a copolymer of at least one olefin and at least one unsaturated carboxylic acid, (a2) Inorganic binder, (b) Lubricants, (c) Thickening agents and / or rheological additives, (d) Further additives, and (e) Fillers A coating composition containing the following is provided. All the advantages, characteristics, and specific features described above apply appropriately to this particular embodiment of the present invention in light of other embodiments and characteristics of the present invention.

[0047] According to a preferred embodiment of the present invention, therefore, (a1) An organic binder comprising a copolymer of at least one olefin and at least one unsaturated carboxylic acid, (a2) Inorganic binder, (b) Lubricants, (c) Thickening agents and / or rheological additives, (d) Further additives, (e) Platelet-shaped particles, and (f) Filler A coating composition containing the following is provided.

[0048] All the advantages, characteristics and specific features described above apply appropriately to this particular embodiment of the present invention in light of further embodiments and characteristics of the present invention. As already stated, the compositions of the present invention are aqueous compositions, that is, the compositions of the present invention contain water as a solvent or dispersant. Typically, the compositions of the present invention contain water in an amount of 40 to 98% by mass, particularly 50 to 95% by mass, preferably 60 to 90% by mass, and more preferably 60 to 85% by mass, based on the coating composition. Furthermore, the coating composition preferably contains only small amounts of organic solvents and volatile organic compounds (VOCs). Typically, the coating composition contains organic solvents and volatile organic compounds in amounts of less than 3% by mass, particularly less than 1% by mass, preferably less than 0.5% by mass, more preferably less than 0.3% by mass, and most preferably less than 0.1% by mass, based on the coating composition. Preferably, the coating composition does not contain organic solvents and volatile organic compounds. Here, with respect to the viscosity of the coating composition of the present invention, this can vary over a wide range. However, in light of the present invention, particularly good results are obtained when the coating composition has a Brookfield dynamic viscosity at 20°C in the range of 2 to 5,000 mPas, particularly 5 to 1,000 mPas, preferably 5 to 500 mPas, preferredly 10 to 100 mPas, and especially preferably 30 to 50 mPas. With viscosities within the above range, a particularly thin and uniform topcoat coating can be obtained.

[0049] This invention Second A further aspect of the present invention, according to its embodiments, is the use of the above-described coating composition as a topcoat for producing a coating having a selectively adjustable coefficient of friction on a metal substrate, particularly a metal substrate coated with a cathodic protection coating. For further details of this aspect of the present invention, one can refer to the description of other aspects of the present invention, which are applicable in accordance with the use of the present invention. Furthermore, the present invention The third Another aspect of the present invention, according to its embodiments, is a method for producing a coating having an adjustable coefficient of friction, (a) In the first method step, a substrate having a cathode-protective coating applied to at least some area is supplied, (b) In a second method step following the first method step (a), the coating composition according to any one of claims 1 to 14 is applied to at least some area of ​​the substrate, and (c) A method wherein, in a third method step following the second method step (b), the coating composition applied in the second method step (b) is dried. In light of the present invention, it is particularly preferable that in the third method step (c), the coating composition applied to the substrate in the second method step (b) is cured and / or crosslinked.

[0050] Typically, the substrate contains or consists of a metal. Preferably, the substrate consists of a metal. In this regard, particularly good results are obtained when the metal is selected from the group consisting of iron, aluminum, magnesium, and mixtures and alloys thereof. In light of the present invention, the metal is selected from iron and its alloys, and is particularly preferably steel. In light of the present invention, the substrate means an article that can be coated with a coating composition. Typically, in light of the present invention, the substrate is selected from sheets, molded bodies, small parts, and mixtures thereof. In light of this, the base material is a small part, preferably a large quantity of material, and is particularly preferably selected from screws, nuts, bolts, washers, rivets and mixtures thereof. In light of the present invention, the base material is preferably a screw or a nut, and more preferably a bolt.

[0051] In particular, the specific advantages of the coating composition and method of the present invention, namely the specific setting of the coefficient of friction, are especially effective in the case of screws. With respect to a cathodic protection coating applied to a substrate over at least some area, preferably the entire surface, it typically contains a metal selected from the group consisting of zinc, aluminum, magnesium, nickel, and mixtures and alloys thereof. Preferably, the cathode corrosion protection coating comprises zinc and its alloys. In light of the present invention, it is often shown that the cathode protection coating is selected from the group of zinc-containing coatings, particularly electroplated zinc coatings, particularly electroplated zinc-nickel coatings, hot-dip galvanized coatings, zinc powder coatings, particularly zinc paint, and zinc flake coatings. Preferably, the cathode protection coating is selected from the group of electroplated zinc coatings, particularly electroplated zinc-nickel coatings, zinc powder coatings, and zinc flake coatings. Zinc powder coatings and zinc flake coatings may also particularly include zinc alloys. Preferably, the zinc alloy includes aluminum and / or magnesium in addition to zinc, preferably aluminum and magnesium.

[0052] In light of the present invention, it is clearly shown that in step (b) of the method, the coating composition is applied to the substrate or the cathodic protection coating with a layer thickness in the range of 1 to 12 μm, particularly 1 to 10 μm, preferably 1 to 8 μm, most preferably 2 to 8 μm, and very preferably 2 to 7 μm. The coating composition can be applied in step (b) by any suitable method. However, typically in step (b), the coating composition is applied to the substrate by spraying, brushing, rubbing, rotating, dipping, or rotating dipping. Particularly good results are obtained when the coating composition is applied in step (b) by dipping or rotating dipping. Dipping or rotating dipping is particularly suitable for coating large quantities of material, such as small parts. In light of the present invention, it is particularly preferable that the coating composition is applied over the entire surface of the substrate or the cathode protective coating.

[0053] The temperature at which the coating composition is dried in step (c) can vary over a wide range depending on the selected substrate, the applied cathode protection coating, and the applied coating composition. However, it has been shown that the method is useful when the coating composition is dried in step (c) at a temperature in the range of 20 to 300°C, particularly 30 to 250°C, preferably 40 to 200°C, more preferably 50 to 180°C, particularly preferably 55 to 160°C, and most preferably 60 to 150°C. At the temperatures mentioned above, rapid drying, curing, and / or crosslinking of the binder system usually occur, and the decomposition of the organic binder is avoided. Similarly, it has been found that it is advantageous in step (c) of the method for the coating composition to be dried for 1 to 30 minutes, particularly 2 to 25 minutes, preferably 3 to 20 minutes, and more preferably 5 to 15 minutes.

[0054] As already mentioned, within the scope of the present invention, the coefficient of friction of the coating, particularly the topcoat, obtained in the desired manner can be set. Accordingly, particularly good results can be obtained when the coefficient of friction of the coated substrate, measured in accordance with DIN EN ISO 16047:2013-01, is set in the range of 0.09 to 0.16 by applying the coating composition. The coefficient of friction is set in particular by the amount of organic binder and the type and amount of lubricant. For further details of this aspect of the present invention, one can refer to the prior description of other aspects of the present invention, which are appropriately applied according to the methods of the present invention. Finally, the present invention The fourth Further aspects of the present invention, according to the embodiments described above, are metal substrates obtained by the coating compositions or the methods described above.

[0055] Typically, the substrate still has a coating, i.e., a cured coating composition, particularly a topcoat, and especially a basecoat, between the coatings. In light of the present invention, it is preferable that the coating contains a lubricant in an amount of 1 to 25% by mass, particularly 1 to 20% by mass, preferably 1.5 to 17% by mass, more preferably 2 to 15% by mass, and especially preferably 2.5 to 12% by mass, based on the coating. Typically, the coating, especially the topcoat, contains an organic binder in an amount of 60-99% by mass, particularly 65-99% by mass, preferably 70-98% by mass, preferredly 75-97% by mass, and especially preferably 80-96% by mass, based on the coating, especially the topcoat. In light of the present invention, when a mixture of organic and inorganic binders is used, it is often shown that the coating, particularly the topcoat, contains the organic binder in an amount of 25-70% by mass, particularly 30-65% by mass, preferably 35-60% by mass, more preferably 40-55% by mass, and most preferably 43-53% by mass, based on the coating, particularly the topcoat. Similarly, in light of the present invention according to this embodiment, it is preferable that the coating, particularly the topcoat, contains an inorganic binder in an amount of 25-70% by mass, particularly 30-65% by mass, preferably 35-65% by mass, preferredly 40-55% by mass, and especially preferably 43-53% by mass, based on the coating, particularly the topcoat.

[0056] It is more clearly shown that the mass ratio of the organic binder to the inorganic binder is in the range of 1.5:1 to 1:2, particularly 1.5:1 to 1:1.5, and preferably 1.1:1 to 1:1.1, based on the mass of the organic binder and the mass of the inorganic binder in the coating, especially the top coat. It is also preferable that the coating, particularly the topcoat, contains platelet-shaped particles in an amount of 0.5 to 20, particularly 1 to 15% by mass, preferably 1.5 to 12% by mass, and more preferably 1.5 to 10% by mass, based on the coating, particularly the topcoat. In light of this, particularly good results are obtained when the coating contains a total amount of lubricant and platelet-shaped particles in the range of 1.5 to 45% by mass, especially 2 to 35% by mass, preferably 3.5 to 25% by mass, and more preferably 4 to 20% by mass, based on the coating composition. Therefore, the coating, especially the top coat, preferably has a layer thickness in the range of 1 to 10 μm, particularly 1 to 8 μm, preferably 1 to 7 μm, more preferably 2 to 7 μm, and most preferably 2 to 6 μm.

[0057] Furthermore, it is preferable that the coefficient of friction of the coated substrate, measured in accordance with DIN EN ISO 16047:2013-01, varies within the range of 0.09 to 0.16. For further details regarding the substrate of the present invention, one can refer to the above description of other embodiments of the present invention, which are appropriately applicable to the substrate of the present invention. The contents of the present invention are described below with reference to exemplary, non-limiting embodiments. [Examples]

[0058] To further illustrate the present invention and its advantages, a series of tests were conducted using the topcoat composition of the present invention applied to screws. The sliding and frictional properties of the screws were then measured. 1. Examples 1-3 First, the properties of topcoat compositions containing only organic binders based on acrylic ester / methacrylic ester / styrene copolymers are investigated. Micronized polyethylene wax and thickeners (RheoByk 7420 ES and Optigel) are added to the compositions. The coating compositions are shown in Table 1 below.

[0059] [Table 1]

[0060] Using an immersion rotary machine, the coating composition is applied to the entire surface of the screw to a thickness of 7 μm, and then dried at 120°C for 20 minutes. Next, the screw is subjected to friction coefficient measurement in accordance with DIN EN ISO 16047:2013-01. It is found that both the total friction coefficient and the friction coefficients of the head and threads fall within a specific VDA window of 0.09 to 0.16. For further investigation, multiple tightening cycles (5 tightening cycles) were examined on steel surfaces, surfaces coated with organic cathode dipping coating (KTL), and aluminum surfaces. It was shown that a multi-fit friction coefficient window was observed only on steel. All three coating compositions exhibited excellent heat dissipation behavior. The values ​​are shown in Table 2 below.

[0061] [Table 2]

[0062] 2. Examples 4 and 5 In addition to tests 1-3 described above, tests were conducted using acrylic acid copolymer as a binder. The compositions are shown in Table 3 below, and the friction and slip properties tests are shown in Table 4 below. From Table 4, it can be seen that compositions 4 and 5 exhibit excellent thermal soldering properties. The coefficient of friction is also always within the VDA window. This is also true for multiple fastenings of steel, KTL, and aluminum.

[0063] [Table 3]

[0064] [Table 4]

[0065] 3. Examples 6-9 Examples 6 to 9 use a mixture of an organic ethylene-acrylic acid copolymer and an inorganic binder in the form of a colloidal silica sol. A thickener and micronized polyethylene wax are added to each of compositions 6 to 9 in an amount of 1% by mass. The compositions are shown in Table 5 below. The compositions are reapplied to screws, and their frictional properties are tested. The test results are shown in Table 6 below. It can be seen that the coefficient of friction is always within the desired VDA window.

[0066] [Table 5]

[0067] [Table 6]

[0068] 4. Examples 10-17 Furthermore, two series of tests were conducted, one using an organic binder based on acrylic acid copolymer (Examples 10-13). In addition, a second series of tests was conducted using an inorganic binder in the form of colloidal silica sol (Examples 14-17). Table 7 shows the compositions for Test System 1 (Examples 10-13), and Table 9 shows the examples for Test System 2 (Examples 14-17). Each composition was applied to a bolt, and its sliding and frictional properties were tested. The results of these tests are shown in Tables 8 and 10. It is shown that both topcoats 10-13 containing pure organic binders and topcoats 14-17 containing mixtures of organic and inorganic binders have excellent properties. All topcoats meet VDA specifications in terms of friction coefficient, total friction coefficient, head friction coefficient, and thread friction coefficient. Heat dissipation behavior is also always acceptable.

[0069] [Table 7]

[0070] [Table 8]

[0071] [Table 9]

[0072] [Table 10]

[0073] 5. Examples 18-28 Furthermore, tests are conducted using a binder system that includes an organic binder in the form of an acrylic acid copolymer and an inorganic binder in the form of a colloidal silica sol, with various lubricants added. Using an immersion rotary machine, the coating composition is applied to the entire surface of the screw to a thickness of 7 μm, and then dried at 150°C for 30 minutes. Next, the screw is subjected to friction coefficient measurement in accordance with DIN EN ISO 16047:2013-01.

[0074] [Table 11]

[0075] [Table 12]

[0076] [Table 13]

[0077] [Table 14] Preferred embodiments of the present invention are as follows: [1] An aqueous coating composition for producing a coating having an adjustable coefficient of friction, particularly a top coat, (a) an organic binder comprising a copolymer of at least one unsaturated hydrocarbon and at least one unsaturated carboxylic acid, and (b) Lubricant A coating composition characterized by containing the following: [2] The coating composition according to [1], characterized in that the unsaturated hydrocarbon is selected from the group consisting of aliphatic hydrocarbons having a vinyl group, aromatic hydrocarbons having a vinyl group, aliphatic hydrocarbons having an alkynyl group, aromatic hydrocarbons having an alkynyl group and mixtures thereof, particularly aliphatic hydrocarbons having a vinyl group, aromatic hydrocarbons having a vinyl group and mixtures thereof, preferably aliphatic hydrocarbons having a vinyl group. [3] The unsaturated hydrocarbon is an aliphatic and / or aromatic C having an alkynyl group. 2 -C 20 Compounds, aliphatic and / or aromatic carbon compounds having a vinyl group. 2 -C 20 Compounds and mixtures thereof, in particular aliphatic and / or aromatic carbon compounds having an alkynyl group. 2 -C 12 Compounds, aliphatic and / or aromatic carbon compounds having a vinyl group. 2 -C 12 Compounds and mixtures thereof, preferably aliphatic and / or aromatic C having an alkynyl group. 2 -C 10 Compounds, aliphatic and / or aromatic carbon compounds having a vinyl group. 2 -C 10 Compounds and mixtures thereof, preferably aliphatic and / or aromatic carbon compounds having an alkynyl group. 2 -C 8 Compounds, aliphatic and / or aromatic carbon compounds having a vinyl group. 2 -C 8 Compounds and mixtures thereof, particularly preferred aliphatic C having a vinyl group. 2 -C 6 Compounds, more preferably aliphatic C having a vinyl group. 2 -C 4 Alkenes, particularly preferably C 2 and C 3 The coating composition according to [1] or [2], characterized by being selected from alkenes. [4] The unsaturated carboxylic acid is C 2 -C 20 Alkenic acid, especially C 2 -C 12 Alkenic acid, preferably C 2 -C 10 Alkenic acid, preferably C 2 -C 4 Alkenic acid, more preferably C 2 -C 3 A coating composition according to any one of the above [1] to [3], characterized by being selected from alkenic acid, and their esters and amides. [5] The unsaturated carboxylic acid is acrylic acid, acrylic acid and C 1 -C 10 Esters with alcohol, methacrylic acid, methacrylic acid and C 1 -C 10 Esters with alcohols, fumaric acid, maleic acid, especially acrylic acid, acrylic acid and C 1 -C 10 Esters with alcohols, methacrylic acid, and methacrylic acid and C 1 -C 10 A coating composition according to any one of the above claims [1] to [4], characterized by being selected from the group of esters with alcohols. [6] The coating composition according to any one of [1] to [5], characterized in that it contains the organic binder in an amount of 2 to 70% by mass, particularly 5 to 60% by mass, preferably 10 to 50% by mass, and more preferably 10 to 40% by mass, based on the coating composition. [7] The coating composition according to any one of the above [1] to [6], characterized in that the lubricant is selected from the group consisting of organic lubricants, inorganic lubricants and mixtures thereof, preferably organic lubricants. [8] The coating composition according to any one of the above [1] to [7], characterized in that the lubricant is selected from the group consisting of wax, graphene, graphite, boron nitride, molybdenum disulfide, plastic particles, particularly polyether ketone (PEK), polyether ether ketone (PEEK), polyphenylene sulfide (PPS), polyether sulfone (PES), polyetherimide (PEI), polyamideimide (PAI) and mixtures thereof, finely powdered sulfur and mixtures thereof, preferably wax. [9] The coating composition according to any one of the above [1] to [8], characterized in that it contains the lubricant in an amount of 0.1 to 10% by mass, particularly 0.3 to 8% by mass, preferably 0.5 to 5% by mass, and more preferably 0.8 to 4% by mass, based on the coating composition.

[10] A coating composition according to any one of the above [1] to [9], characterized in that it does not contain a fluorine-containing compound, and in particular does not contain an organofluorine-containing compound.

[11] The coating composition according to any one of the above [1] to

[10] , characterized by containing platelet-shaped particles.

[12] A coating composition according to any one of the above [1] to

[11] , characterized by containing an inorganic binder.

[13] The coating composition according to

[12] , characterized in that the inorganic binder is selected from silane, silane hydrolysate, silicate, polysiliconate, and mixtures thereof.

[14] (a1) An organic binder comprising a copolymer of at least one olefin and at least one unsaturated carboxylic acid, (a2) Inorganic binders, and (b) Lubricant The coating composition according to

[12] or

[13] , characterized by containing the above.

[15] Use of the coating composition described in any one of [1] to

[14] above as a top coat for producing a coating having an adjustable coefficient of friction on a metal substrate, in particular a metal substrate coated with a cathodic protection coating.

[16] A method for producing a coating having a selectively adjustable coefficient of friction, (d) In the first method step, a substrate is provided having a cathode-protective coating applied to at least some areas, (e) In a second method step following the first method step (a) above, the coating composition described in any one of items [1] to

[14] above is applied to at least some area of ​​the substrate, and (f) In a third method step following the second method step (b), the coating composition applied in the second method step (b) is dried. A method characterized by the following features.

[17] The method according to

[16] , characterized in that the coefficient of friction of the coated substrate, as measured according to DIN EN ISO 16047:2013-01, is set to be in the range of 0.09 to 0.16.

[18] A metal substrate comprising a coating, which is obtained using a coating composition described in any one of the above items [1] to

[14] or by the method described in any one of the above items

[16] or

[17] .

[19] The metal substrate according to

[18] , characterized in that the coating contains the lubricant in an amount of 1 to 25% by mass, particularly 1 to 20% by mass, preferably 1.5 to 17% by mass, more preferably 2 to 15% by mass, and particularly preferably 2.5 to 12% by mass, based on the coating.

[20] The metal substrate according to

[18] or

[19] , characterized in that the coating contains the organic binder in an amount of 60 to 99% by mass, particularly 65 to 99% by mass, preferably 70 to 98% by mass, more preferably 75 to 97% by mass, and most preferably 80 to 96% by mass, based on the coating.

Claims

1. An aqueous coating composition for producing a coating having an adjustable coefficient of friction, (a1) An organic binder in an amount of 3 to 25% by mass based on the coating composition, comprising a copolymer of at least one unsaturated hydrocarbon and at least one unsaturated carboxylic acid or its derivative, (a2) An inorganic binder in an amount of 3 to 20% by mass based on the coating composition, selected from the group consisting of silane, tetraethyl orthosilicate (TEOS), tetramethyl orthosilicate (TMOS), silane hydrolysate, colloidal silicic acid, water glass and mixtures thereof, and (b) A lubricant in an amount of 0.5 to 5% by mass based on the coating composition, selected from the group consisting of wax, graphene, graphite, boron nitride, molybdenum disulfide, plastic particles, finely powdered sulfur and mixtures thereof. A coating composition comprising a total content of 10 to 50% by mass of a binder based on the coating composition, wherein the mass ratio of the inorganic binder to the organic binder in the coating composition is 1.5:1 to 1:1.5 based on the mass of the inorganic binder and the organic binder in the composition, and the coating composition is characterized in that it does not contain PTFE and PVDF.

2. The coating composition according to claim 1, characterized in that the unsaturated hydrocarbon is selected from the group consisting of aliphatic hydrocarbons having a vinyl group, aromatic hydrocarbons having a vinyl group, aliphatic hydrocarbons having an alkynyl group, aromatic hydrocarbons having an alkynyl group, and mixtures thereof.

3. The aforementioned unsaturated hydrocarbon is an aliphatic and / or aromatic C having an alkynyl group. 2 -C 20 Compounds, aliphatic and / or aromatic carbon compounds having a vinyl group. 2 -C 20 The coating composition according to claim 1, characterized by being selected from compounds and mixtures thereof.

4. The unsaturated carboxylic acid or its derivative is C 2 -C 20 The coating composition according to claim 1, characterized in that it is selected from alkenic acid and its esters and amides.

5. The unsaturated carboxylic acid or its derivative is selected from the group consisting of acrylic acid, an ester of acrylic acid and C 1 -C 10 alcohol, methacrylic acid, an ester of methacrylic acid and C 1 -C 10 alcohol, fumaric acid, and maleic acid. The coating composition according to claim 1, characterized in that it is so selected.

6. The coating composition according to claim 1, characterized in that it contains the organic binder in an amount of 10 to 25% by mass based on the coating composition.

7. The coating composition according to claim 1, characterized in that it contains the lubricant in an amount of 0.8 to 4% by mass based on the coating composition.

8. The coating composition according to claim 1, characterized in that it does not contain a fluorine-containing compound.

9. The coating composition according to claim 1, characterized by containing platelet-shaped particles.

10. Use of the coating composition according to any one of claims 1 to 9 as a top coat for producing a coating having an adjustable coefficient of friction on a metal substrate.

11. A method for manufacturing a coating having a selectively adjustable coefficient of friction, (a) In the first method step, a substrate is provided in which at least some areas are coated with a cathodic protection coating, (b) In a second method step following the first method step (a), the coating composition according to any one of claims 1 to 9 is applied to at least some area of ​​the substrate, and (c) In a third method step following the second method step (b), the coating composition applied in the second method step (b) is dried. A method characterized by the following features.

12. The method according to claim 11, characterized in that the coefficient of friction of the coated substrate, as measured according to DIN EN ISO 16047:2013-01, is set to a range of 0.09 to 0.

16.

13. A metal substrate comprising a coating, obtained using the coating composition described in any one of claims 1 to 9.

14. The metal substrate according to claim 13, characterized in that the coating contains the lubricant in an amount of 1 to 25% by mass based on the coating.

15. The metal substrate according to claim 13, characterized in that the coating contains the organic binder in an amount of 60 to 99% by mass based on the coating.

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