Process for coating an object

Abstract

The invention relates to a process for coating an object, preferably (slidable) objects which are subject to wear, in particular cooking and baking equipment, with at least two layers, the process comprising the following steps: 1) producing a first layer, comprising the steps of a) applying to the object, in particular the cooking and baking equipment, a powder mixture, dry or in the form of a dispersion in a liquid, comprising powder particles of at least one polyphenylene sulfide (PPS) polymer and optionally a polyaryletherketone (PAEK) polymer, it being possible for the powder mixture to be prepared without adding fluorine or fluorine-containing compounds, the application preferably being performed electrostatically in a fluidised-bed sintering process or as a dispersion in liquid, in particular water; b) in the case of dispersion, completely removing the liquid; c) heating the powder mixture to form a polycondensate; and d) preferably baking the powder mixture above the melting temperature of the polymers; producing a second layer or third layer or further layers on the first layer, the sub-steps a) to c) being repeated and step d) being performed either for each layer individually or for at least two layers together.

Description

[0001] Description

[0002] Method for coating an object

[0003] The present invention relates to a method for coating an article, preferably a wear-prone (sliding) article, in particular cooking and baking accessories, with at least two layers, and to an article coated by the method, preferably a wear-prone (sliding) article, in particular cooking and baking accessories or parts with food contact.

[0004] PTFE coatings are state of the art and are usually applied as a triple coating for higher quality cookware, i.e. in three layers, usually with at least two baking processes. First, a base layer, usually consisting of a binding resin dissolved in a solvent, e.g. PAI dissolved in NMP, is wet-sprayed, dried, and pre-crosslinked. Subsequently, a transition layer and a top layer are sprayed on wet-on-wet, with the top layer essentially containing fluoropolymer, usually PTFE. The entire coating is then baked for around 10 minutes at 420°C. These coatings can be modified with pigments and various fillers. The disadvantage is the use of fluoropolymers and the fact that the baking temperature is significantly higher than the decomposition temperature of PTFE, which can produce substances that are hazardous to health (PEAS).Furthermore, these coatings have the disadvantage of releasing toxic substances (PEAs) when used at high temperatures. So-called ceramic sol-gel coatings, which contain silicones to achieve the non-stick effect, are also known. These coatings are usually very brittle and not durable.

[0005] According to EU regulations, the limit value for PEAS in the EU is to be reduced from 2024 onwards to such an extent that, from today's perspective, PTFE coatings ("Teflon") will have to be replaced as non-stick coatings.

[0006] The object of the present invention is to provide a method for a universally applicable coating for an object, preferably a wear-prone (sliding) object, in particular for cooking and baking utensils or parts with food contact, without fluoropolymers and without the addition of fluorine.

[0007] The above object is achieved by providing a method according to claim 1, and an article, preferably a wear-prone (sliding) article, in particular cooking and baking accessories or parts with food contact, according to claim 17. Preferred embodiments are presented in the subclaims. According to the invention, the term cooking and baking accessories or parts with food contact encompasses any article which, in terms of its shape, is suitable for holding food and then cooking and baking. Therefore, in addition to pans, baking trays, baking pans, etc., as well as grill trays, grill containers, grill racks, etc. are also encompassed by the above term, as are machine parts for processing food.

[0008] In a first aspect of the invention, a method for coating an article, preferably a wear-prone (sliding) article, in particular cooking and baking accessories or parts with food contact, with at least two layers is provided, comprising the following steps:

[0009] 1) Production of a first layer comprising a) application of a powder mixture, dry or as a dispersion in a liquid, comprising powder particles of at least one polyphenylene sulfide (PPS) polymer and optionally a polyaryletherketone (PAEK) polymer, wherein the powder mixture can be produced without the addition of fluorine or fluorine-containing compounds, to the article, in particular the cooking and baking accessory, wherein the application is preferably carried out electrostatically, in a fluidized bed sintering process or as a dispersion in liquid, in particular water; b) in the case of dispersion, complete removal of the liquid; c) heating of the powder mixture to form a polycondensate; and d) preferably baking of the powder mixture above the melting temperature of the polymers;

[0010] 2) producing a second layer or third layer or further layers on the first layer, wherein sub-steps a) to dc) are repeated and step d) is carried out either for each layer individually or for at least 2 layers together.

[0011] According to the invention, the powder mixture can be produced without the addition of fluorine or fluorine-containing compounds. This is particularly the case according to the invention if the powder mixture, after combustion at 900 ° C - 1000 ° C in a moist, oxygen-rich atmosphere, does not exceed certain limit values ​​of total fluoride. Therefore, the powder mixture preferably comprises at most 1000 ppb, preferably at most 100 ppb, particularly preferably at most 25 ppb total fluorides, measured by

[0012] Combustion ion chromatography (TOF-CIC) .

[0013] In detail, to carry out the combustion ion chromatography (TOF-CIC) measurement method according to the invention, samples of the powder mixture are filled into ceramic boats and introduced into a furnace where pyrohydrolysis takes place at 900-1000 °C in a humid, O2-rich environment. The samples are oxidized under these conditions, the strong carbon-fluorine bond is broken, and the vapors are passed through an absorption solution containing Ar. The HF produced during the combustion of organic fluorine dissociates in the absorption solution to form H+ and F- ions. The samples of the absorption solution, which also contains an internal standard for calibrating the analytical results, are then transferred to an ion chromatograph for analysis, where fluoride is measured.

[0014] Surprisingly, the article produced by the process according to the invention possesses equally good or even better sliding properties than PEEK or PTFE coatings, based on the coating. In the Taber test (ISO 9352, ASTM D 1044, DIN EN 438-6), the wear is only approximately 10% of that of a PEEK coating with fluoropolymer or 5% of that of a fluoropolymer coating.

[0015] The Taber test is used to determine the abrasion resistance of a coating. The abrasion stress is generated by two friction rollers coated with abrasive particles, which are pressed onto the rotating test specimen with a specified force. The evaluation is performed using differential weighing, from which the abraded portion of the sample is determined. Alternatively, the wear depth / roughness can be determined, or visual documentation can be performed.

[0016] In addition, the method according to the invention is suitable for coating objects, preferably those subject to wear (sliding

[0017] ) article, in particular cooking and baking accessories or parts that come into contact with food. The non-stick effect (tested using standard pancakes in accordance with DIN EN 60350-2) of the coating produced by the process according to the invention corresponded to the expectations for a non-stick effect for cookware without the addition of oil and without any fluorine components. In particular, when carrying out the process according to the invention for producing the coating, no fluorosurfactant is required to promote leveling.

[0018] Finally, cooking and baking accessories or parts that come into contact with food are subject to wear and tear during use, caused by turning and cleaning processes. To maintain their properties, it is therefore important to minimize wear and tear and ensure their longevity. This is especially important in professional applications, where the stress is approximately 10 times greater than in household use.

[0019] Furthermore, unlike conventional coatings based on the state of the art, the described new coating can be applied completely solvent-free in powder form, for example, electrostatically. Another advantage is that the curing step can also be performed using radiation, for example, a laser, instead of an oven.

[0020] Preferably, in the process according to the invention, the powder mixture for the first layer contains a higher proportion of PPS polymer than the powder mixture for the second layer, preferably more than 60 wt.%, more preferably more than 70 wt.%, even more preferably more than 90 wt.%, even more preferably more than 95 wt.%, particularly preferably more than 99 wt.% polyphenylene sulfide based on the total mass of the dry powder mixture.

[0021] Preferably, in the process according to the invention, the powder mixture for the second, third or further layer, preferably at least the cover layer, contains a higher proportion of PAEK polymer than the powder mixture for the second first layer, preferably more than 60 wt.%, more preferably more than 70 wt.%, even more preferably more than 90 wt.%, even more preferably more than 95 wt.%, particularly preferably more than 99 wt.% PAEK polymer based on the total mass of the dry powder mixture.

[0022] Preferably, in the process according to the invention, the baking temperature (substrate temperature) during the production of the first respective layer is 40-60°C above the liquidus temperature of the polymer, in the case of a mixture of the higher-melting polymer, or 350-360°C if a uniform baking temperature is taken over all layers.

[0023] Preferably, the process, in particular in the step of heating the powder mixture to form a polycondensate, is carried out without using a fluorosurfactant.

[0024] Preferably, in the process according to the invention, the powder mixture further comprises tin (Sn), preferably 0.1 to 5 wt.%, more preferably 0.1 to 2 wt.%, even more preferably 0.5 to 1.5 wt.%, in particular 1 wt.%, based on the

[0025] Total mass of the dry powder mixture.

[0026] Preferably, in the process according to the invention, the powder mixture is present as a dispersion and preferably the liquid in the dispersion comprises water.

[0027] In the process according to the invention, the powder mixture preferably comprises at least two PAEK polymers, or at least one PAEK polymer and one PPS polymer, wherein the PAEK polymers are preferably selected from the group consisting of polyetheretherketone (PEEK), polyetherketone (PEK), polyetherketoneketone (PEKK), and polyetherketoneetherketone (PEKKEK). The polymers preferably have different melting temperatures and / or preferably different melt viscosities.

[0028] In the process according to the invention, the average melt viscosity of at least one polymer is preferably at most 150 Pa.s, preferably at most 120, more preferably at most 100 Pa.s, or especially preferably at most 90 Pa.s, measured according to ISO 11443 at 400°C. This significantly smooths the flow upon heating for polycondensation on a surface to be coated. The non-stick effect of the coated surface is thereby improved. This applies even when the particles are large relative to the layer thickness (e.g., 25 μm grain size D50 for a 25 μm layer thickness).

[0029] In the process according to the invention, the powder mixture preferably also comprises a dry lubricant, excluding fluoropolymers and PEAS, preferably an element from the group consisting of polyamideimide (PAI), polyimide (PI), graphite, M0S2, boron nitride (hexagonal modification; a-boron nitride), and a mixture thereof. This can further improve wear resistance.

[0030] In the process according to the invention, the powder mixture preferably also comprises a reinforcing element, metallic fillers and their oxides, ceramic and mineral fillers, glass particles in the form of flakes or spheres, glass or carbon fibers, or carbon black. The elements are preferably present in nanoparticle size, i.e., smaller than 100 nm, preferably 1 to 100 nm. Particularly preferred are the nanoparticle elements according to ISO / TS 27687:2008, which are nanoobjects with three external dimensions, which are preferably 1 to 100 nm.

[0031] In a second aspect of the invention, an article, preferably a wear-prone (sliding) article, in particular cooking and baking accessories, is provided, which has a coating produced by the method according to the first aspect of the invention.

[0032] In the following, the invention is explained in more detail using exemplary embodiments and the associated figures.

[0033] The figures serve solely to facilitate a better understanding of the invention and are only schematic and not drawn to scale. The invention is not intended to be limited to the exemplary embodiments. Identical or equivalent parts are provided with the same reference numerals.

[0034] Figure 1 shows cooking and baking accessories with an applied dispersion layer in schematic cross section according to a reference example, Figure 2 shows cooking and baking accessories according to a

[0035] Reference example,

[0036] Figure 3 shows a process sequence for the coating for the production of the cooking and frying accessories according to the invention using various process stages,

[0037] Figure 4 shows a flow diagram for a coating using a dispersion process.

[0038] An object to be coated or an area of ​​the cooking and baking accessory to be coated represents the substrate SU to be coated. The surface to be coated can first be subjected to a chemical and / or mechanical activation treatment. This can involve mechanical roughening, for example using a sandblaster, or etching with acids, alkalis, or plasma or laser treatment. A suitably pre-treated surface has additional chemical / physical bonding points, is clean and free of grease, and, in the case of roughening, has a larger surface area, which leads to better adhesion of the coating to be applied.

[0039] A layer DS of a dispersion is then applied to this surface. This layer contains all the components of the coating in a finely divided and as homogeneous a particle size distribution as possible when dispersed in a solvent or solvent mixture. An application method is selected which is suitable for producing a desired layer thickness. The average particle size (D50) of the solids contained in the dispersion corresponds at most to the desired layer thickness for the coating, but is preferably selected to be smaller. Figure 1 shows a substrate SU coated in this way with an applied dispersion layer DS.

[0040] After conducting a temperature program during which the substrate coated with the dispersion layer DS or the cooking and baking accessory is heated to a temperature above the melting point of the thermoplastic(s) contained in the dispersion, a homogeneous coating BS is obtained that is pore-free and thus dense, exhibiting good mechanical cohesion and good adhesion to the substrate SU. Figure 2 shows the finished cooking and baking accessory according to a reference example.

[0041] It is possible to apply the coating to only part of the surface. The remaining area not to be coated can be covered, or an application method for the dispersion can be selected which can differentiate between different surface areas, for example painting or printing. The covering can also be achieved using a shadow mask while the dispersion is sprayed on. This shadow mask can also be in the form of a film which is applied to the surface of the substrate SU and leaves out the areas of the surface to be coated. After the dispersion layer DS has been applied, the film can be removed and, for example, peeled off, with the areas of the dispersion layer DS applied over it also being peeled off.

[0042] Figure 3 shows the method according to the invention for coating an article, preferably a wear-prone (sliding) article, in particular cooking and baking accessories or parts that come into contact with food, with at least two layers. For this purpose, after the application of the first dispersion layer DS1, as shown in Figure 3a, at least the solvent is removed; alternatively, the first dispersion layer is additionally pre-compacted by a temperature treatment. In a second step, the dispersion coating is repeated and a second dispersion layer DS2 is applied.

[0043] If necessary, this layer can also be pre-compacted and the coating step repeated. Finally, as shown in Figure 3c, the dispersion layer structure consisting of several sublayers is heated to a temperature above the melting point of the thermoplastic in a final step, resulting in a fully compacted, pore-free, closed coating BS on the substrate SU.

[0044] A composition suitable for application by dispersion methods and also friction-reduced according to the invention contains, for example, solids in the following proportions by weight:

[0045] For DS 1 : 100 weight percent PPS For DS2 : 100 weight percent PAEK

[0046] Color additives can be added if necessary. It is possible to apply one or more coats.

[0047] The solids are dispersed, optionally with aids, in a solvent, which may be water or, advantageously, is miscible or mixed with water, e.g., alcohol and, in particular, isopropanol. The dispersion mixture then contains approximately 30 percent by weight of the above-mentioned solids.

[0048] Figure 4 illustrates the process sequence just described more clearly using a flow chart. The process comprises, as step 1, the production and preparation of the powder mixture. For this purpose, the ingredients, which are selected from thermoplastic polymer, filler, and dry lubricant, are either brought to a suitable particle size, preferably by grinding and / or by subsequent sorting according to grain size, in accordance with the desired, narrowest possible grain size distribution.

[0049] In parallel, in step 2, the solvent is prepared, which is preferably environmentally and health-safe, preferably water-based, and in particular consists of a mixture of alcohol and water, e.g., isopropanol and water. An advantageous solvent composition contains, for example, 25 to 75 percent by weight of isopropanol in water. A solvent with approximately 25-50 percent by weight of isopropanol in water is particularly preferred.

[0050] In step 3, the dispersion is prepared by adding the solvent to the prepared powder mixture, maintaining a solids content of preferably 20 to 50 percent by weight. To improve dispersion stability, known dispersion aids can be added in small amounts.

[0051] In step 4, the surface of the object is coated, for example by spraying, dipping, brushing, printing, or spin-coating. The aim is to achieve the most homogeneous layer thickness possible for the dispersion layer, and any areas of the surface not to be coated are left out of the coating.

[0052] In step 5, the solvent is removed, preferably by evaporation, which may optionally be assisted by reduced pressure or elevated temperature, for example 80 °C.

[0053] In the next step (6), the cooking and baking accessories with the applied dried dispersion layer are converted into a homogeneous coating by heating and melting the thermoplastics, and then baked, preferably above the melting temperature of the polymers. The cooking and baking accessories are then cooled again.

[0054] According to the invention, a second layer (optionally also a third layer or further layers) is then produced on the first layer, repeating sub-steps 1 (if necessary to produce a second or further layer with a different composition) and 2 to 6. Baking above the melting temperature of the polymers is carried out either for each layer individually or for at least 2 layers together.

[0055] A finished coating can then be obtained at point 7.

[0056] According to a variant VI of the process, it is possible to repeat steps 4 to 7 directly after step 5. A second variant V2 follows step 6, wherein, after melting the first dispersion layer, a new dispersion layer is applied (step 4) and compacted accordingly (steps 5 to 7).

[0057] According to a third variant V3 of the process, after producing a first coating according to step 6, a second partial coating layer, different from the first coating, is applied. For this purpose, a further dispersion is produced according to process steps 1 to 3, and the cooking and baking accessories are coated therewith according to steps 4 to 6. Here, too, the process according to variants VI and V2 can be modified by repeating individual process steps or individual process step sequences in order to achieve a desired layer thickness.

[0058] In particular, when using fine particles for the dispersion, a particularly homogeneous coating can be obtained, which makes multiple coatings advantageous or even necessary due to the small particle diameters.

[0059] Although the invention has been explained using only a few exemplary embodiments, it is not limited to these. Possible variations arise in particular through a suitable selection of fillers and, if appropriate, through mixtures of different fillers. The proportions of the components of the coating used are selected depending on the desired load on the coating. The same applies to the layer thicknesses, which are not limited to the examples given. The coating is advantageously applied to metallic surfaces, although the coating can also be applied to other surfaces such as ceramic, glass or suitable plastic.

[0060] Examples

[0061] PAEK polymers are known for their good sliding properties, with PTFE usually being included as a dry lubricant in friction-optimized compounds. Tests have shown that by omitting PTFE, the wear rate was reduced to 10% compared to a compound with 3% PTFE content. For the tests, stainless steel sheets were coated with a 60 μm layer thickness and then subjected to Taber tests with the following parameters:

[0062] All quantities are given in percent by weight (wt.%) unless otherwise stated.

[0063] Model:

[0064] Taber Rotary Abraser / Model no: 1700

[0065] Tracking force per roll: 1000g

[0066] Abrasives TABER Industries

[0067] S-33 Sandpaper Strips

[0068] Lot No.: 84944

[0069] All samples were coated with a layer thickness of approximately 60 pm, which corresponds to the thickness of conventional high-quality triple non-stick coatings.

[0070] The number of cycles was measured until the first spots were worn through to the substrate.

[0071] Test 1 : Coating 3-fold PTFE, manufacturer PPG, System Eclipse : Result: 150 cycles

[0072] Attempt 2:

[0073] Coating 90% PEEK / 5% pigment black / 3% PTFE / 2% graphite :

[0074] 300 cycles

[0075] Attempt 3 :

[0076] Coating 92% PEEK / 5% pigment black / 2% graphite: 1500 cycles

[0077] Attempt 4 :

[0078] Layer 1, layer thickness 40gm: 84% PPS / 5% pigment black / 5% PEEK / 1% tin / 5% glass flake

[0079] Layer 2, layer thickness 20 gm: PEEK / 10% PPS / 5% pigment black / optionally 1% graphite or boron nitride (hexagonal) (makes no difference)

[0080] Fired together 360°C: 2000 cycles

[0081] Individually fired 2x 360°C: > 3000 cycles

[0082] Surprisingly, the coating according to the invention is 10 times more resistant than a developed PTFE coating and 2 times more resistant than a simple PEEK coating.

[0083] In addition, the coating according to the invention surprisingly exhibits a non-stick effect that is sufficiently good for cookware. A pancake according to DIN standards can be removed easily when new. However, even after the wear test described above, the non-stick effect does not diminish; it remains just as good as when new. The fact that the coating is not particularly oleophobic and therefore does not have a large contact angle with oil and grease is not a disadvantage in use, as lubrication with oils and greases works particularly well.

[0084] Tests in the dishwasher have shown that the coating according to the invention is completely dishwasher safe, with 1000 cycles resulting in no damage.

[0085] In particular, the coating according to the invention is resistant to alkalis and hot water. The latter was measured by 100 hours in an autoclave at 130°C (under pressure).

[0086] Further examples:

[0087] Attempt 5:

[0088] Layer 1, layer thickness 20pm: 84% PPS / 5% pigment black / 5% PEEK / 1% tin / 5% glass flake

[0089] Baking temperature 320°C

[0090] Layer 2, layer thickness 20 pm: PEEK / 10% PPS / 5% pigment black / optionally 1% graphite or boron nitride (hexagonal) (makes no difference)

[0091] Baking temperature 350°C

[0092] Attempt 6:

[0093] Layer 1, layer thickness 10pm: 84% PPS / 5% pigment black / 5% PEEK / 1% tin / 5% glass flake

[0094] Layer 2, layer thickness 10 pm: PEEK / 10% PPS / 5% pigment black / optionally 1% graphite or boron nitride (hexagonal) (makes no difference)

[0095] Sprayed wet in wet in aqueous dispersion and after drying baked together at 350°C

[0096] Tests 7, 8, 9: Layer 1, layer thickness 20 pm: 84% PPS / 5% pigment black / 5% PEEK / 1% tin / 5% glass flake

[0097] Layer 2, layer thickness 40 pm: PEEK / 10% PPS / 5% pigment black / optionally 1% graphite or boron nitride (hexagonal) (makes no difference)

[0098] Fired together 400°C, 380°C, 360°C

[0099] Attempt 10:

[0100] Layer 1, layer thickness 30pm: 84% PPS / 5% pigment black / 5% PEEK / 1% tin / 5% glass flake

[0101] Layer 2, layer thickness 10 pm: PEEK / 10% PPS / 5% pigment black / optionally 1% graphite or boron nitride (hexagonal) (makes no difference)

[0102] Fired together 400°C, 380°C, 360°C

[0103] As the curing temperature decreases, the wear resistance and non-stick properties improve. As the curing temperature increases, the thermal stability (short-term) improves. Starting at 380°C, the coating was no longer liquid, even though the respective liquidus temperatures were 285°C and 342°C.

[0104] All tests can be applied either wet in dispersion, for example by spraying or dipping, or dry as powder, for example by fluidized bed coating or electrostatically sprayed.

[0105] In the latter case of powder application, the drying process is omitted.

[0106] In all described embodiments, the melting point of the described finished coating is not negatively affected by the PPS, but is at that of PEEK, i.e. 342 °C or higher.

Claims

Patent claims 1 . A method for coating an article, preferably a wear-prone (sliding) article, in particular cooking and baking accessories or parts with food contact, with at least two layers, comprising the following steps: 1) Production of a first layer comprising a) application of a powder mixture, dry or as a dispersion in a liquid, comprising powder particles of at least one polyphenylene sulfide (PPS) polymer and optionally a polyaryletherketone (PAEK) polymer, wherein the powder mixture can be produced without the addition of fluorine or fluorine-containing compounds, to the article, in particular the cooking and baking accessory, wherein the application is preferably carried out electrostatically, in a fluidized bed sintering process or as a dispersion in liquid, in particular water; b) in the case of dispersion, complete removal of the liquid; c) heating of the powder mixture to form a polycondensate; and d) preferably baking of the powder mixture above the melting temperature of the polymers; 2) producing a second layer or third layer or further layers on the first layer, wherein sub-steps a) to c) are repeated and step d) is carried out either for each layer individually or for at least 2 layers together.

2. The method according to claim 1, wherein the powder mixture for the first layer contains a higher proportion of PPS polymer than the powder mixture for the second layer, preferably more than 60 wt.%, more preferably more than 70 wt.%, even more preferably more than 90 wt.%, even more preferably more than 95 wt.%, particularly preferably more than 99 wt.% polyphenylene sulfide based on the total mass of the dry powder mixture.

3. The method according to any one of the preceding claims, wherein the powder mixture for the second, third or further layer, preferably at least the cover layer, contains a higher proportion of PAEK polymer than the powder mixture for the first layer, preferably more than 60% by weight, more preferably more than 70% by weight, even more preferably more than 90% by weight, even more preferably more than 95% by weight, particularly preferably more than 99% by weight of PAEK polymer based on the total mass of the dry powder mixture.

4. Method according to one of the preceding claims, wherein the baking temperature (substrate temperature) during the production of the respective layer is 40-60°C above the liquidus temperature of the polymer, in the case of a mixture of the higher-melting polymer, or 350-360°C if a uniform baking temperature is taken over all layers.

5. The process according to any one of the preceding claims, wherein the process, in particular in the step of heating the powder mixture to form a polycondensate, is carried out without using a fluorosurfactant.

6. The method according to any one of the preceding claims, wherein the powder mixture comprises at most 1000 ppb, preferably at most 100 ppb, particularly preferably at most 25 ppb total fluorides, measured by combustion ion chromatography (TOF-CIC).

7. The method according to any one of the preceding claims, wherein the powder mixture further comprises tin (Sn), preferably 0.1 to 5 wt.%, more preferably 0.1 to 2 wt.%, even more preferably 0.5 to 1.5 wt.%, in particular 1 wt.%, based on the total mass of the dry powder mixture.

8. A method according to any one of the preceding claims, wherein the powder mixture is in the form of a dispersion and the liquid comprises water.

9. The method according to any one of the preceding claims, wherein the powder mixture comprises at least one PAEK polymer and PPS polymer, wherein the PAEK polymers are preferably selected from the group consisting of polyetheretherketone (PEEK), polyetherketone (PEK), polyetherketoneketone (PEKK) and polyetherketoneetherketone (PEKKEK).

10. The process according to claim 9, wherein the polymers have different melting temperatures.

11. The process according to claim 9 or 10, wherein the PAEK polymers have different melt viscosities, measured according to ISO 11443 at 400°C.

12. A process according to any one of the preceding claims, wherein the average melt viscosity of at least one polymer at most 150 Pa.s, preferably at most 120, more preferably at most 100 Pa.s or particularly preferably at most 90 Pa.s, measured according to ISO 11443 at 400°C.

13. The method according to any one of the preceding claims, wherein the powder mixture further comprises a dry lubricant, excluding fluoropolymers and PFAS, preferably an element from the group consisting of polyamideimide (PAI), polyimide (PI), graphite, M0S2, boron nitride (hexagonal modification; a-boron nitride) and a mixture thereof.

14. A method according to any one of the preceding claims, wherein the powder mixture further contains a reinforcing element, metallic fillers and their oxides, ceramic and mineral fillers, glass particles in the form of flakes or spheres, glass or carbon fibers or carbon black.

15. The method of claim 14, wherein the elements are in nano-sized form.

16. The method of claim 14, wherein the elements are in the order of magnitude of the layer thickness before the final layer is applied.

17. Object, preferably one subject to wear (sliding ) Article, in particular cooking and baking accessories or parts with food contact, which has a coating produced by the process according to one of claims 1 to 16.

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