Non-fluorinated PES-based coating

Abstract

The present invention relates to a coated heating element (1) for household appliances, comprising a metallic substrate (2) coated on at least one face (2a) by a coating (3) free of fluorocarbon resin and comprising at least the following layers, in this order from the metallic substrate (2): (3a) a primer layer made of polyethersulfone (PES) or a mixture of polyethersulfone (PES) and one or more silicone resins, and optionally: one or more fillers and / or one or more additives, and / or one or more colorants; (3b) one or more intermediate layer(s) made of polyethersulfone (PES) or a mixture of polyethersulfone (PES) and one or more silicone resins, and optionally: one or more fillers, and / or one or more additives, and / or one or more colorants. (3c) top layer made of polyethersulfone (PES),or consisting of a mixture of polyethersulfone (PES) and one or more silicone resins, or consisting of one or more silicone resins, and optionally: one or more fillers and / or one or more additives, and / or one or more coloring agents; it being understood that layer (3a), layer (3c) and at least one of the layers (3b) are different.

Description

Title of the invention: Non-fluorinated PES-based coating

[0001] The invention applies in the field of non-stick coatings for household articles, heated or capable of being heated, in particular for cooking articles and electric cooking appliances.

[0002] Cookware coated with PTFE (polytetrafluoroethylene) is popular on the market because it allows for cooking with little or no added fat and is easy to clean. However, an inherent weakness of these coatings is their low mechanical resistance, especially at high temperatures. Another inherent weakness of PTFE is its ductility, which makes the coatings easily marked, scratched, and worn by metal utensils (spatulas, forks, spoons, immersion blenders, etc.).

[0003] To remedy this, numerous technical solutions have been proposed which consist of reinforcing the coating with hard fillers or by interposing hard underlayers of inorganic or organic type.

[0004] In the case of primers reinforced by hard organic or inorganic fillers, significant improvements in abrasion resistance are indeed observed, but impacts to the metal are also observed when cooking foods such as pork ribs or when using metal spatulas.

[0005] In the case of hard inorganic bases such as, for example, those made from enamel or metal oxides, abrasion resistance is further improved and the problem of impacts is limited, although not eliminated.

[0006] Organic polymer underlayers are also known. These underlayers effectively reduce the appearance of scratches considerably, or even eliminate them. This strategy is therefore very advantageous. The polymers used are very often thermoplastic polymers with high heat resistance and a high melting point, such as polyaryletherketones, and in particular oxy-1,4-phenylenephenylene-oxy-1,4-phenylene-carbonyl-1,4-phenylene or PEEK, or even phenylene sulfides.

[0007] Pure silicone resins are described as being relatively non-stick and resistant to temperatures above 220-230°C. On the other hand, they are considered to have poor adhesion to the substrate.

[0008] Conversely, silicone-polyester resins are very common in mold making because they are non-stick while adhering to the substrate and are compatible with stamping processes. However, they degrade at temperatures above 230°C. Indeed, the temperature range for use of cookware The operating temperature range is between 50 and 250°C, and it is not surprising to reach temperatures of 300°C or even 350°C in the case of items with induction bases. Their use is therefore incompatible with the temperatures typically encountered in the culinary field.

[0009] The present invention addresses the technical problem of improving the anti-stick properties of a coating with high thermo-mechanical properties and, where appropriate, its suitability for stamping.

[0010] The present invention also deals with the technical problem of alternative solutions to PTFE-type fluorinated resin-based coatings.

[0011] The present invention proposes an alternative to coatings based on a majority of PTFE in order to obtain good resistance to mechanical wear of the coatings, in particular by kitchen utensils for culinary articles and thus improve the durability of their mechanical resistance, in particular when hot and / or their cleanability, in order to extend the life of the article. DEFINITIONS

[0012] For the purposes of this invention, the term "layer" should be understood to mean a continuous or discontinuous layer. A continuous layer (also called a monolithic layer) is a single unit forming a flat surface that completely covers the area on which it is laid. A discontinuous layer (or non-monolithic layer) may comprise several parts and is therefore not a single unit.

[0013] The terms "base coat," "primer coat," "bonding coat," or "bonding primer" refer to all the layers from the first coat applied directly to the substrate (it is preferable that this coat adheres well to the substrate and provides all its mechanical properties to the coating: hardness, scratch resistance) to the last layer before the first intermediate or decorative coat. The first layer of the coating is a primer coat.

[0014] The term "intermediate layer" refers to the layers inserted between the primary layer(s) and the finishing layer(s). The intermediate layer(s) may be "decorations" or "decorative layers." The intermediate layer(s) is / are not intended to come into contact with food.

[0015] The term "finish coat" means a continuous surface layer applied after the intermediate coat(s) if the coating includes one or more intermediate coat(s), or after the primer coat(s). The final layer of the coating is a finish coat. Usually, at least the final finish coat, or even all the finish coats, is / are transparent to allow visibility of the underlying layers, particularly when the underlying layers are decorative layers. The finish coat(s) protect the underlying layers from mechanical stress and give the coating its non-stick properties. Preferably, in the case of a cookware item or electric cooking appliance, the final finishing layer is intended to come into contact with food.

[0016] The term "decoration" or "decorative layer" means one or more continuous or discontinuous layers comprising a pigment composition. The decoration may be in the form of one or more patterns, or one or more colors. A decoration is clearly visible to the user with the naked eye and at a typical viewing distance from the household item.

[0017] The term "overlapping layers" refers to layers that are partially or completely superimposed. These layers may take the form of partially overlapping patterns, for example concentric disks.

[0018] The term "adjacent layers" refers to non-superimposed layers. These layers may be in the form of identical or different non-superimposed patterns, preferably uniformly distributed.

[0019] A "temperature reference pigment composition" is defined as a composition comprising a pigment which, at a given temperature, indicates to the user that the optimal operating temperature has been reached. This indication is made by comparing the colors of the thermochromic pigment composition and the temperature reference pigment composition. The optimal operating temperature is reached either when the colors are identical or when the colors are visually very different.

[0020] The "temperature reference pigment composition" may include a pigment that exhibits:

[0021] - the same color as the thermochromic pigment composition at temperature for optimal use,

[0022] * either because this pigment has the same color at room temperature as the Thermochromic pigment composition at optimal use temperature and does not change color with temperature.

[0023] * either because this pigment has a different color at room temperature of that of the thermochromic pigment composition which evolves to the same color as the thermochromic pigment composition at the optimal operating temperature,

[0024] - a color very different from that of the thermochromic pigment composition the optimal operating temperature, whether this pigment changes color or not with temperature changes.

[0025] The optimal operating temperature can be reached when the color of the temperature reference pigment composition corresponds to a color indicated in the user guide for the household item comprising the coating of the invention or to a color indicated on a color scale provided to the user with said item.

[0026] The reference temperature pigment composition is thermochromic or thermostable.

[0027] The reference temperature pigment composition can be, for example, a reference cooking temperature pigment composition or an indication of risk of overheating.

[0028] For the purposes of this invention, the term "thermochromic semiconductor" refers to a mineral or organic compound that undergoes a reversible color change upon temperature increase. The gradual and reversible thermochromic nature of these semiconductor compounds is due to the decrease in the band gap of the semiconductor caused by the expansion of the material. Indeed, the periodicity of the anion and cation network leads to the clustering of energy levels into energy bands. The band containing the highest energy is called the valence band, and the band containing the lowest energy is called the conduction band. Between these two bands, there is a band gap.The color of a semiconductor material can originate from the presence of a charge transfer which corresponds to the passage of an electron either from a valence band to a conduction band on the same atom, or commonly from the orbital of an anion to the orbital of a cation (interatomic photon absorption).

[0029] In the fields of application envisaged for the present invention, the optimal conditions are reached when the coating reaches a temperature suitable for cooking food, preferably between 100 and 250°C.

[0030] For the purposes of this invention, "thermochromic pigment or pigment composition" means a pigment or pigment composition that changes color with temperature within a given temperature range, this change being reversible. This color change is visible to the user with the naked eye at normal viewing distances.

[0031] The term "thermostat pigment" means a pigment which does not exhibit a change of color when subjected to a temperature rise within a given temperature range or which exhibits a change of hue when subjected to a temperature rise within a given temperature range so small that it is not visible to the user with the naked eye and at a conventional operating distance.

[0032] Preferably, the thermostable pigments have a color difference AE* between 25°C and 200°C of less than 10, AE* being defined by the CIE1976 formula in the CIELAB color space:

[0033] , r~~< 77 777 7“ A£ = J(L2 -Lj ) + (^-67^ + ^2 -b^2

[0034] Li*, ai* and bi* characterizing the L*a*b values ​​of said compound at room temperature

[0035] L2*, a2* and b2* characterizing the L*a*b values ​​of said compound at 200°C.

[0036] By "the colours are identical" we mean indistinguishable by the user to the naked eye and at a normal operating distance.

[0037] For the purposes of this invention, the term "cooking article" means an object intended for cooking and being heated by an external heating system, such as frying pans, saucepans, sauté pans, woks, or barbecue grills. A cooking article is capable of transferring the heat energy supplied by this external heating system to a material or food in contact with said article.

[0038] For the purposes of this invention, the term "electric cooking appliance" means a heating object having its own heating system, such as an electric crepe maker, electric raclette appliance, electric fondue appliance, electric grill, electric griddle, electric cooker, bread machine, or electric pressure cooking appliance.

[0039] The term "coating" refers to all the layers adhering to and covering the metallic substrate. The coating obtained according to the invention is advantageously solid; "solid" is understood to mean the characteristic of a cohesive material insoluble in water, in common solvents, and in food components such as aqueous or fatty mixtures, even if the material may exhibit high hardness or high flexibility, such as an elastomer.

[0040] In the present invention, the % by weight are expressed in dry weight, i.e. without solvent. Summary of the invention

[0041] A first object of the invention relates to a coated heating element (1) for household articles, comprising a metallic substrate (2) coated on at least one face (2a) by a coating (3) free of fluorocarbon resin and comprising at least the following layers and in this order from the metallic substrate (2):

[0042] (3a) a primer layer made of polyethersulfone (PES) or a mixture of polyethersulfone (PES) and one or more silicone resins, and possibly: - one or more fillers and / or - one or more additives, and / or - one or more coloring agents

[0043] (3b) one or more intermediate layer(s) made of polyethersulfone (PES) or a mixture of polyethersulfone (PES) and one or more silicone resins, and possibly: - of one or more charge(s), and / or - of one or more additive(s), and / or - of one or more coloring agent(s)

[0044] (3c) topcoat made of polyethersulfone (PES), or made of a a mixture of polyethersulfone (PES) and one or more silicone resins, or consisting of one or more silicone resins, and possibly: - of one or more charge(s) and / or - of one or more additive(s), and / or - of one or more coloring agent(s);

[0045] it being understood that layer (3a), layer (3c) and at least one of the layers (3b) are different.

[0046] Another object of the invention relates to a method for manufacturing a household article comprising a heating element coated (1) with a coating (3) according to the invention characterized by the following steps:

[0047] a) a step of supplying a metallic substrate (2) in the form of a substantially flat metallic substrate comprising two opposite faces or of a support (2) of convex or hollow shape defining an inner face (21) concave and an outer face (22) convex;

[0048] b) where appropriate, where a metallic substrate in the form of a substantially flat metallic substrate is provided in step (a), a shaping step of said substrate to give it the form of a support (2) of convex or hollow shape defining an inner face (21) concave and an outer face (22) convex, said step (b) being carried out either before step (a), or before step (d) of producing layers (3a), (3b) and (3c) of the coating (3), or after step (f) of baking and before the optional step (g) of producing layer (3d) or after step (g);

[0049] c) optionally, a treatment step of at least one face (2a) of the metallic substrate (2), to obtain a treated face (2a) promoting the adhesion of a primer layer (3a) on the support (2);

[0050] d) a step of applying layers (3a), (3b) and (3c) of the coating (3);

[0051] e) optionally a drying step between 50°C and 150°C after application of each of the layers (3a) (3b) and (3c);

[0052] f) optionally a cooking step of the element obtained in step d) or e) at a temperature between 250°C and 420°C;

[0053] g) optionally, a step of applying the layer (3d) to the element obtained in step d), e) or f);

[0054] h) optionally a cooking step of the element obtained in step g) at a temperature between 250°C and 420°C.

[0055] Another object of the invention relates to a household article comprising a coated heating element (1) according to the invention or capable of being obtained according to the process of the invention. FIGURES

[0056] [Fig. 1]: Diagram of the heating element according to the invention with layer (3b) is continues and covers the entire layer (3a)

[0057] [Fig.2] ; diagram of the heating element according to the invention with layer (3b) ne does not cover the entire layer (3a) and forms a decoration

[0058] [Fig. 3]: Diagram of the heating element according to the invention with layer (3b) composed of two sets (i) and (j)

[0059] [Fig. 4] ; pattern distribution diagram. 4A = adjacent non-pattern patterns overlapping. 4B = partially overlapping patterns. 4C = overlapping patterns.

[0060] [Fig.5] Diagram of a cooking article according to the invention

[0061] [Fig.6] Diagram of an electric cooking appliance according to the invention DETAILED DESCRIPTION

[0062] A first object of the invention relates to a coated heating element (1) for household articles, comprising a metallic substrate (2) coated on at least one face (2a) by a coating (3) free of fluorocarbon resin and comprising at least the following layers and in this order from the metallic substrate (2):

[0063] (3a) a primer layer made of polyethersulfone (PES), or a mixture of polyethersulfone (PES) and one or more silicone resins, and possibly: - one or more filler(s) and / or - one or more additive(s), and / or - one or more coloring agent(s)

[0064] (3b) one or more intermediate layer(s) made of polyethersulfone (PES) or a mixture of polyethersulfone (PES) and one or more silicone resins, and possibly: - of one or more charge(s), and / or - of one or more additive(s), and / or - of one or more coloring agent(s)

[0065] (3c) topcoat made of polyethersulfone (PES), or made of a a mixture of polyethersulfone (PES) and one or more silicone resins, or consisting of one or more silicone resins, and possibly: - of one or more charge(s) and / or - of one or more additive(s), and / or - of one or more coloring agent(s);

[0066] it being understood that layer (3a), layer (3c) and at least one of the layers (3b) are different.

[0067] Advantageously, the layers (3a), (3b) and (3c) form a coating (3) which coats the metallic substrate (2). This coating (3) has non-stick properties and forms a non-stick coating.

[0068] Advantageously, the layer (3a) is in contact with the metallic substrate (2) by one of its faces by its face (2a).

[0069] When the household item is a cooking utensil or an electric cooking appliance, the coated face (2a) of the metallic substrate forms a cooking surface. In other words, the coating (3) according to the invention is then intended to come into contact with food. Advantageously, the finishing layer (3c) is then in contact with food on one of its faces and thus forms a cooking surface (5).

[0070] The coating (3) according to the invention does not comprise a fluorocarbon resin, also called a fluorinated polymer or fluoropolymer. In other words, said coating (3) is free of fluorocarbon resin. Thus, the coating (3) does not comprise or emit perfluoroalkyl and polyfluoroalkyl compounds.

[0071] Advantageously, the thickness of each of the coating layers (3a), (3b) and (3c) is from 5 pm to 15 pm.

[0072] At least one intermediate layer (3b) is present in the coating (3) according to the invention. This at least one intermediate layer (3b) is different from at least one primer layer (3a) and at least one topcoat layer (3c). Preferably, in this case, all the intermediate layers (3b) are different from the primer layer(s) (3a) and the topcoat layer(s) (3c).

[0073] Advantageously, layer (3a), layer (3c) and all layers (3b), when there are several, are all different. PES

[0074] Advantageously, the PES is micronized. The PES can have a d50 ranging from 5 pm to 20 pm, preferably from 8 pm to 18 pm. The term "D50" means, in the context of the present invention, the maximum dimension present by 50% of the particles by number.

[0075] According to embodiments, the PES content in the primary layer (3a) is less than the PES content in the layer(s) (3b).

[0076] In this case, advantageously, the PES content is increasing from the primer layer (3a) to the finishing layer (3c).

[0077] Thus, advantageously, the PES content of the primary layer (3a) represents from 50% to less than 75% by weight of the primary layer (3a), preferably from 55% to 70%.

[0078]

[0079]

[0080]

[0081]

[0082]

[0083]

[0084]

[0085]

[0086]

[0087]

[0088]

[0089] Advantageously, the PES content of the intermediate layer (3b) represents from 75 to less than 85% by weight of the intermediate layer (3b), preferably from 75% to 80%. Advantageously, the PES content of the topcoat (3c) represents 85% to 98% by weight of the topcoat (3c), preferably 85% to 95%. In these embodiments, advantageously, layers (3a) to (3c) are made of polyethersulfone (PES) and optionally: - of one or more charge(s) and / or - of one or more additive(s), and / or - of one or more coloring agent(s). In these embodiments, advantageously, layers (3a) to (3c) are made of polyethersulfone (PES) and: - of one or more charge(s); - of one or more additive(s); - and one or more coloring agent(s). In these embodiments, advantageously, the filler content decreases from the primer layer (3a) to the finishing layer (3c). According to other embodiments, the PES content in the primary layer (3a) is greater than the PES content in the layer(s) (3b). In this case, advantageously, the PES content decreases from the primer layer (3a) to the finishing layer (3c). Thus, advantageously, the PES of the primary layer (3a) represents 25% to 30% by weight of the primary layer. Advantageously, the PES of the intermediate layer (3b) represents from 20% to less than 25% by weight of the intermediate layer. Advantageously, the PES of the topcoat (3c) represents from 10% to less than 20% by weight of the topcoat, preferably from 15% to less than 20%. In these embodiments, advantageously, layers (3a) to (3c) are made of polyethersulfone (PES) and silicone resins, and optionally: - of one or more charge(s) and / or - of one or more additive(s), and / or - of one or more coloring agent(s). In these embodiments, advantageously, layers (3a) to (3c) are made of polyethersulfone (PES) and silicone resins and: - of one or more charge(s); - of one or more additive(s); - and one or more coloring agent(s).

[0090] In these embodiments, advantageously, the silicone resin content increases from the primer layer (3a) to the finishing layer (3c).

[0091] In these embodiments, advantageously, the PES content decreases from the primer layer (3a) to the finishing layer (3c) and the silicone content increases from the primer layer (3a) to the finishing layer (3c).

[0092] In these embodiments, advantageously, the (PES+silicone resin) content of the layers (3a), (3b) and (3c) ranges from 40% to 90% or from 50% to 90%, preferably from 60% to 90%, even more preferably from 70% to 90% by weight of each layer.

[0093] In these embodiments, the presence of silicone resins and PES makes it possible to give both the non-stick character of the coating and its suitability for stamping in the case where the coated heating element is shaped after deposition of the coating (3).

[0094] These embodiments are thus particularly suitable in the case of shaping the heating element to give it a convex shape, as for a pan for example.

[0095] According to other embodiments, in particular when the coated heating element is shaped by stamping after deposition of the coating (3) and the coating (3) is subjected to high stresses during this stamping step, the layer (3c) may consist of polyethersulfone (PES) and silicone resins and: - of one or more charge(s); - of one or more additive(s); - and one or more coloring agent(s).

[0096] the PES content being between 60% and 80% by weight of the layer (3c), the silicone resin content being between 5% and 30% by weight of the layer (3c) and the (PES+silicone resin) content being between 70% and 98%, preferably between 80% and 98%, even more preferably between 90% and 98% by weight of the layer (3c).

[0097] In this case, layers (3a) and (3b) can be made of PES and: - of one or more charge(s); - of one or more additive(s); - and one or more coloring agent(s).

[0098] Advantageously, the PES of the primary layer (3a) represents from 50% to less than 75% by weight of the primary layer, preferably from 55% to 70%. Advantageously, the PES of the intermediate layer (3b) represents from 75 to less than 85% by weight of the intermediate layer, preferably from 75% to 80%.

[0099] The high PES content of layer (3c) as well as layers (3a) and (3b) ensures good stamping resistance under high stress. The presence of silicone resin in layer (3c) further guarantees good non-stick properties.

[0100] These embodiments are thus particularly suitable in the case of shaping the heating element to give it a hollow shape for a saucepan for example.

[0101] CHARGES

[0102] Advantageously, the primer layer(s) (3a) and / or the intermediate layer(s) (3b) and / or the layer(s) (3c) comprises one or more fillers. According to this embodiment, the primer layer(s) (3a) and / or the intermediate layer(s) (3b) and / or the layer(s) (3c) comprises less than 40%, preferably less than 30%, by weight of fillers relative to the total weight of said layer, preferably between 5 and 25% by weight.

[0103] The fillers within the meaning of the invention make it possible to provide mechanical reinforcement and can also provide hydrophobic properties, while improving the mechanical resistance and thermal conductivity of the coating.

[0104] The fillers do not only have the function of adding color to the coating, but can contribute to it.

[0105] Advantageously, the filler(s) is / are chosen from the group consisting of ceramic (SiO2, etc.) and / or mineral and / or metallic (Al2O3, TiO2, etc.) fillers and / or silicas and / or diamond particles.

[0106] Preferably, the filler(s) is / are chosen from the group consisting of metal oxides, metal carbides, metal oxynitrides, metal nitrides, and their mixtures.

[0107] Advantageously, said metal is a transition metal, such as at least one of the elements selected from B, Ni, Ti, Zr or Hf.

[0108] Preferably, the charge(s) is / are chosen from the group consisting of:

[0109] - Reinforcement charges: hard organic or inorganic charges; the charges hard inorganic materials are preferably particles of silicon carbide or alumina or zirconia or graphite, or ceramics, or carbonate, or hydrated alumina, aluminum trihydroxide or one or more metal oxide(s), graphite, graphene;

[0110] - other fillers for reinforcement selected from metallic oxides: silica, micas, lamellar charges, clays such as montmorillonite, sepiolite, gypsite, kaolinite and laponite, zinc dioxide, quartz, and zirconium phosphate, alumina, zirconia, zinc oxide, copper oxide, iron oxide;

[0111] - fillers selected from reinforcing fibers: glass or carbon fiber or aramid;

[0112] - conductive charges comprising a transition metal carbide and / or a nitride of transition metal: characterized in that the transition metal is at least one of the elements selected from B, Ni, Ti, Zr or Hf,

[0113] for example: Cubic boron nitride, diamond particles, metallic particles;

[0114] - lamellar charges that can confer lubricating properties, such as by Examples include clays, graphene, and graphite.

[0115] Among the fillers in combination with silicone resins, the preferred fillers are:

[0116] - reinforcing fillers: silica or carbonates with minimum filler content 10-15% / wt and potentially up to 60% / wt,

[0117] - alumina, hydrated alumina, aluminum trihydroxide,

[0118] - silica (precipitated or pyrogenated) with a d50 <0.1 pm and a specific surface BET > 30 m2 / g and preferably between 30 and 500 m2 / g,

[0119] - or a mixture of quartz and silica, diatomaceous earth or crushed quartz, titanium, mica, talc, kaolin, barium sulfate, slaked lime, zinc oxide, expanded vermiculite, non-expanded vermiculite, calcium carbonate etc.

[0120] Preferably, the filler(s) is / are chosen from the group consisting of alumina, silicon carbide, tungsten carbide, boron nitride, quartz, and mixtures thereof.

[0121] Advantageously, the fillers present in the primary layer(s) (3a) or the intermediate layer(s) (3b) are hard inorganic fillers, preferably oxides, carbides, metallic nitrides, preferably alumina, silicon carbides or fumed silica.

[0122] Certain hard inorganic fillers such as silicon carbide, in addition to their mechanical reinforcement performance, also have the advantage of being conductive fillers and therefore provide excellent thermal conductivity.

[0123] Adding this type of filler improves the culinary experience with better heat distribution from the metallic substrate to the food in contact with the coating.

[0124] Advantageously, the average diameter d50 of the charges is between 0.1 and 50 pm, advantageously still between 5 and 15 pm.

[0125] Advantageously, the proportion of fillers in a layer is between 0.5 and 30% by dry weight relative to the total weight of said layer after baking, preferably between 5 and 20%.

[0126] Advantageously, the proportion of charges in layer (3a) is greater than 20% by weight, preferably greater than 30% by weight, relative to the total weight of said layer.

[0127] Advantageously, the proportion of charges in layer (3c) is less than 10% by weight relative to the total weight of said layer.

[0128] Advantageously, the proportion of charges in layers (3a), (3b) and (3c) can be identical or different.

[0129] Advantageously, the nature of the charges in the layers (3a), (3b) and (3c) can be identical or different.

[0130] ADDITIVES

[0131] Advantageously, the primer layer(s) (3a) and / or the intermediate layer(s) (3b) and / or the layer(s) (3c) comprises one or more additives.

[0132] Advantageously, the additive(s) is / are chosen from the group consisting of antifoaming agents, dispersing agents, wetting agents, thickeners, pH adjusters, reactive silicone oils.

[0133] The said antifoaming agent(s) (is) preferably chosen from the group consisting of mineral oils, diols, hydrocarbons, glycerides, oxyrane, emulsified fatty acids.

[0134] The surfactant(s) is / are preferably chosen from the group consisting of glycol ether, ethoxylated alcohol excluding alkyl phenol ethoxylates (APEs), gemini surfactants.

[0135] The dispersing agent(s) is / are preferably chosen from the group consisting of anionic dispersants such as fatty acid derivatives.

[0136] Said thickeners are preferably chosen from the group consisting of acrylic-based or polyurethane-based copolymer, cellulose, fumed silica.

[0137] Said pH adjusters are preferably chosen from the group consisting of Brønsted bases: ammonia, amines (triethylamine, triethanolamine...), hydroxides (sodium hydroxide, potassium hydroxide...), carbonates.

[0138] Advantageously, the primer layer(s) (3a) and the intermediate layer(s) (3b) comprise one or more acrylic resin(s). The acrylic resin(s) is / are advantageously chosen from the group consisting of polymers resulting from an emulsion polymerization of different monomers with other acrylic-based monomers.

[0139] Advantageously, the primary layer(s) (3a) or the intermediate layer(s) (3b) comprises one or more surfactants.

[0140] Advantageously, the primary layer(s) (3a) or the intermediate layer(s) (3b) further comprises one or more antifoaming agents.

[0141] Advantageously, the primary layer(s) (3a) or the intermediate layer(s) (3b) further comprises water and / or one or more solvents, preferably unlabeled, for example propionamide, or alcoholic, for example dipropylene glycol butyl ether (DPNB). Other solvents are conceivable where appropriate, such as N-formylmorpholine (NFM), N-methyl imidazole (NMI), N-butylpyrrolidone (NBP), dimethyl sulfoxide (DMSO), propylene glycol (PPG), and diethylene glycol.

[0142] Advantageously, the topcoat (3c) comprises a silicone oil.

[0143] Advantageously, silicone oil represents 1 to 5% by weight of the topcoat (3c), preferably 2% to 4%.

[0144] COLOURING AGENTS

[0145] Advantageously, the primer layer(s) (3a) or the intermediate layer(s) (3b) comprises one or more colorant(s). Advantageously, the primer layer(s) (3a) or the intermediate layer(s) (3b) comprises less than 30%, preferably less than 20%, by weight of one or more colorant(s) of the total weight of said layer.

[0146] Advantageously, the colouring agent(s) is / are chosen from the group consisting of thermochromic pigments, thermostable pigments, glitter, preferably holographic glitter, and mixtures thereof.

[0147] Advantageously, the proportion of coloring agents in the layers (3a), (3b) and (3c) is between 0.5 and 50% by dry weight relative to the total weight of said layer after baking.

[0148] Advantageously, the proportion of coloring agents in layers (3a) and (3b) ranges from 10% to 40% by weight relative to the total weight of said layer.

[0149] Advantageously, the proportion of coloring agents in layer (3c), when present, is less than 10% by weight relative to the total weight of said layer.

[0150] Advantageously, the proportion of coloring agents in layers (3a), (3b) and (3c) may be identical or different.

[0151] Advantageously, the nature of the coloring agents in layers (3a), (3b) and (3c) may be identical or different.

[0152] Advantageously, layer (3c) is transparent. In this case, if it includes coloring agents, these coloring agents are glitter. Thermochromic pigments

[0153] Preferably, the thermochromic pigment(s) is / are chosen from the group consisting of Bi2O3, Fe2O3, V2O5, WO3, CeO2, In2O3, Yi^CaojeTii^Vo.ieCW Agi, (Bil x Ax)(Vi_yMy)O4avec - x is equal to 0 or x is between 0.001 and 0.999, - y is equal to 0 or y is between 0.001 and 0.999, - A and M are chosen from the group consisting of nitrogen, phosphorus, an alkali metal, an alkaline earth metal, a transition metal, a post-oxidation metal, a metalloid, or a lanthanide, - A and M are different from each other.

[0154] Given that A and M are different from each other, when:

[0155] - A is an alkali metal, it can be chosen from Li, Na, K, Rb, Cs,

[0156] - M is an alkali metal, it can be chosen from Li, Na, K, Rb, Cs,

[0157] - A is an alkaline earth metal, it can be chosen from Be, Mg, Ca, Sr, Ba,

[0158] - M is an alkaline earth metal, it can be chosen from Be, Mg, Ca, Sr, Ba,

[0159] - A is a transition metal, it can be chosen from Sc, Ti Cr, Mn, Fe, Co, Ni, Cu, Y, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Ta, W, Ir,

[0160] - M is a transition metal; it can be chosen from Sc, Ti, Cr, Mn, Fe, Co, Ni, Cu, Y, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Ta, W, Ir,

[0161] - A is a base metal; it can be chosen from Al, Zn, Ga, In, Sn,

[0162] - M is a base metal; it can be chosen from Al, Zn, Ga, In, Sn,

[0163] - A is a metalloid, it can be chosen from B, Si, Ge, Sb,

[0164] - M is a metalloid, it can be chosen from B, Si, Ge, Sb,

[0165] - A is a lanthanide, it can be chosen from La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu,

[0166] - M is a lanthanide, it can be chosen from La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu.

[0167] Preferably, A and M different from each other are B and / or Mg.

[0168] Preferably, the pigment (Bii_xAx)(Vi yMy)04 has a monoclinic scheelite crystallographic form at room temperature.

[0169] Preferably, x and y are 0, that is, the pigment (Bii_xAx)(Vi yMy)O4 is Bismuth Vanadate (BiVO4). Advantageously, a BiVO4 with a monoclinic scheelite crystallographic structure at room temperature is used.

[0170] Bismuth vanadate is a yellow inorganic compound with the formula BiVO4, widely used for its coloristic properties and lack of toxicity. Registered in the Colour Index International database as QI Pigment Yellow 184, it is notably marketed by the Heubach companies. (Vanadur®), BASF (Sicopal®), FERRO (Lysopac) or even Bruchsaler Farbenfabrik (Brufasol®). Heat-stable pigments

[0171] Preferably, the thermostable pigment(s) is / are chosen from the group consisting of:

[0172] - Titanium rutile-type yellow pigment,

[0173] - Yellow pigment derived from bismuth, for example selected from the vanadates of stabilized bismuth (Py i84)

[0174] - Red pigment, for example selected from perylene red (for example PR149, PR178 and PR224), iron oxide,

[0175] - Orange pigment of the bismuth oxyhalide type (PO85),

[0176] - Bismuth vanadate orange pigment (PO86)

[0177] - Zinc tin titanium orange pigment (PO82)

[0178] - Orange pigment of cerium sulfide (PO75; PO78)

[0179] - Yellow-orange rutile-type pigment of antimony titanium chromium (PBr24)

[0180] - Yellow-orange pigment of the tin and zinc rutile type (Py2i6)

[0181] - Yellow-orange pigment of niobium oxide tin zinc sulfide (Py227)

[0182] - Orange-yellow pigment of double oxides of tin and niobium

[0183] - Co3(PO4)2

[0184] - LiCoPO4

[0185] - CoA12O4

[0186] - Cr2O3

[0187] - TiO2

[0188] - Black pigment PBk28 (Copper chromite black spinel)

[0189] - and their mixtures. Decorations

[0190] According to one embodiment, the layer(s) (3b) is / are continuous and covers the entire layer (3a) (see [Fig.1]).

[0191] According to another embodiment, the layer(s) (3b) do not cover the entire layer (3a) and form at least one decoration (see [Fig.2]).

[0192] Advantageously, the layer(s) (3b) make up several decorations, one (i) comprising one or more thermochromic pigment(s) and the other (j) comprising at least one temperature reference pigment composition (see [Fig.3]).

[0193] According to one embodiment, each of the two decorations (i) and (j) is presented in the form of adjacent non-overlapping motifs. For example, each decoration is represented by different geometric motifs distributed uniformly over the entire surface and alternating with respect to each other (see Figure 4A).

[0194] According to another embodiment, the two decorations (i) and (j) are partially overlapping. For example, each decoration is represented by different geometric patterns distributed evenly over the entire surface and partially overlapping (see Figure 4B).

[0195] Preferably, the two designs (i) and (j) are overlapping, either because one of the two designs is a continuous layer and the other design covers it in the form of patterns, or because the two designs (i) and (j) are in the form of overlapping patterns (see Figure 4C). Glitter

[0196] The glitter used in the context of the present invention can be independently selected from mica glitter, coated or uncoated, silica glitter, coated or uncoated, aluminum glitter, coated or uncoated, iron oxide glitter, coated or uncoated, or mica or silica glitter coated with titanium dioxide. The glitter used in the context of the present invention can be treated to give a particular color effect.

[0197] Advantageously, the glitter(s) is / are particles selected from the group consisting of particles of mica, aluminum, mica coated with titanium dioxide or mixtures thereof. Hologram glitter

[0198] Advantageously, the glitter(s) is / are holographic glitter, that is to say a mixture of magnetizable and non-magnetizable particles.

[0199] Magnetizable particles may advantageously be particles comprising at least one ferromagnetic metal. These magnetizable particles may be homogeneous, i.e., made of the same material, or composite, i.e., having a core-shell structure in which the ferromagnetic metal is located in the core and / or the shell of said particles. Examples of composite magnetizable particles include mica flakes coated with iron oxide Fe2O3 or stainless steel fibers coated with a sol-gel material, as corrosion protection during the coating application stages, or plastic material flakes coated with iron oxide Fe2O3, or flakes whose core is made of a ferromagnetic metal and whose shell is made of a plastic material or a sol-gel material.

[0200] According to one embodiment, a portion of said magnetizable particles is oriented so as to form a three-dimensional decoration.

[0201] Advantageously, the mixture of magnetizable and non-magnetizable particles represents between 1% and 5% by weight of the weight of the layer, preferably between 2% and 3% by weight.

[0202] Advantageously, the percentage of non-magnetizable particles in the mixture of magnetizable and non-magnetizable particles is between 15% and 40% by weight relative to the total weight of the mixture of magnetizable and non-magnetizable particles.

[0203] Advantageously, the magnetizable particles have a D50 dimension less than or equal to 23 pm.

[0204] The term “D50” means, in the context of the present invention, the maximum dimension that 50% of the particles have by number.

[0205] Advantageously, the non-magnetizable particles have a D90 dimension between 20% and 250% of the D90 dimension of the magnetizable particles.

[0206] The term “D90” means, in the context of the present invention, the maximum dimension that 90% of the particles have by number.

[0207] Advantageously, the magnetizable particles and / or the non-magnetizable particles are colored on the surface.

[0208] Advantageously, the non-magnetizable particles are made of mica, aluminum, or mica coated with titanium dioxide.

[0209] Advantageously, the magnetizable particles consist of iron, iron oxide, aluminum coated with iron, or mica coated with iron, the iron being in ferritic form.

[0210] SILICONE RESINS

[0211] In the description text, the expression "#silicone resin#" is used The term "silicone" is used interchangeably to refer to silicone before or after crosslinking. In the description, "silicone" refers to an organopolysiloxane material. Crosslinking is the process of transforming silicone into an insoluble material, for example, through polyaddition, polycondensation, or dehydrogenation. Crosslinking is carried out using precursors, which are generally silicone oils or resins, that crosslink to form a three-dimensional network, creating a material referred to as silicone resin in the description.

[0212] This crosslinking can be achieved by thermal activation, or chemical activation using a catalyst, such as platinum.

[0213] Silicone resins can be obtained from precursors, advantageously soluble in a solvent or emulsified in water, such as oils or crosslinkable resins, in particular selected from: a silicone hydride, a silicone oil resin comprising at least one vinyl group (-CH=CH2), a silicone or silicone-polyester resin (copolymer) comprising at least one alkoxy group, for example methoxy or ethoxy, and / or a silicone or silicone-polyester resin (copolymer) comprising at least one alkoxy group, in particular ethoxy, or a hydroxy group, and mixtures thereof. These precursors have the ability to crosslink to obtain a silicone resin characterized by its insolubility and substantially solid form.

[0214] Advantageously, these precursors are polymeric or oligomeric, either in the form of silicone oils of varying degrees of branching, or in the form of silicone resins of varying degrees of pre-crosslinking, or copolymers of silicone resins such as silicone-polyester, silicone-alkyd, silicone-polyurethane, or silicone-epoxy resins, or in the form of a mixture of silicone oils, silicone resins, and silicone resin copolymers. The silicon atoms may be substituted by alkyl (in particular methyl) or aryl (in particular phenyl) groups, or mixtures thereof. The oils or resins preferably comprise one or more (2, 3, or more) hydroxy or alkoxy functional groups (in particular methoxy, ethoxy, butoxy) as substituents for the silicon atoms.

[0215] Advantageously, the silicone resin(s), obtained after crosslinking of their precursors, i.e. crosslinked(s), is / are chosen from the group consisting of methyl silicones and / or phenyl silicones and / or methyl-phenyl-silicones, methyl silicone-polyester resin (copolymers), phenyl silicone-polyester resin (copolymers), methyl-phenyl silicones-polyester resin (copolymers), silicone-alkyd resin (copolymers), modified silicone resin and their mixtures.

[0216] Advantageously, the silicone resin(s) is / are chosen from the group consisting of methyl silicones and / or phenyl silicones and / or methyl-phenyl-silicones, methyl silicone-polyester resin (copolymers), phenyl silicone-polyester resin (copolymers), methyl-phenyl silicones-polyester resin (copolymers), silicone-alkyd resin (copolymers), modified silicone resin and mixtures thereof.

[0217] Silicone resins can be obtained from precursors, in particular selected from: a silicone hydride, a silicone resin comprising at least one vinyl group (-CH=CH2), a silicone-polyester resin (copolymer) comprising at least one methoxy group, and / or a silicone-polyester resin (copolymer) comprising at least one ethoxy group, and mixtures thereof.

[0218] The silicone resin forms a network which may consist of a combination of 4 simple organosiloxane units designated M, D, T and Q depending on the degree of substitution by the oxygen of the silicon atom, as described in the following table, where R is an organic substituent described later.

[0219] [Tables 1] Structure Degree of substitution by oxygen Symbol 1 M ? '"OSrO"" R 2 0 R Ô ï 3 T ô è 4 Q

[0220] The organopolysiloxane material or polymer is obtained by crosslinking from precursors that may be monomeric or polymeric, or, as an intermediate step, oligomeric. The organopolysiloxane polymer may also be obtained from a mixture of these different types of precursors. When the network contains a higher number of T and Q units than D units, the crosslinking density is higher. The distribution among the M, D, T, and Q units depends on the chemical structure of the precursors, in particular on this M, D, T, and Q distribution within the precursors.

[0221] The polymeric precursors are organopolysiloxanes. These macromolecules are formed of M, D, T, and / or Q units as described in the table, where R is independently an alkyl group, in particular methyl, or aryl group, in particular phenyl, different natures of R being able to be present on the same macromolecule.

[0222] Organopolysiloxanes can be either linear or sparsely branched (predominantly D groups), or branched or highly branched (predominantly T and Q groups). Linear or sparsely branched organopolysiloxanes are generally liquid, more or less viscous at room temperature, and are called silicone oils. Branched or highly branched (pre-crosslinked) organopolysiloxanes form a network at the scale of the individual macromolecule and are called silicone resins. At room temperature, the resins are essentially in solid form, or in liquid form, provided in particular that they have a sufficiently low molecular weight, either as a solution in a solvent or as an aqueous emulsion. They can be copolymerized with organic polymers or oligomers not containing silicon, chosen in particular from polyesters, acrylics, alkyds, polyurethanes, and epoxy resins.

[0223] When the crosslinking is a hydrolysis-polycondensation: it is carried out by means of the reactive hydroxy or alkoxy functions, in particular methoxy, ethoxy or butoxy, present on the organopolysiloxane.

[0224] When the crosslinking is a polyaddition (or hydrosilylation): it takes place by reaction between the reactive vinyl functions (-CH=CH2) present on one of the organopolysiloxanes and the reactive silyl hydride functions (Si-H) present on the other organopolysiloxane mixed with the first.

[0225] All these reactive functions are present on each organopolysiloxane, with at least one present and two, three, or more present... as much as the molecular structure allows. Silicone oils containing at least one reactive function are called "reactive oils." The reactive functions can be located either at the end of the macromolecular chain (termination) or distributed along the chain.

[0226] Silicone-polyester resins in particular have silicone / polyester mass ratios for example 90 / 10, 80 / 20, 70 / 30, 60 / 40, 50 / 50, 40 / 50, 30 / 70, 20 / 80, 10 / 90, advantageously between 80 / 20 and 50 / 50.

[0227] Linear PDMS silicone oils, pure or pre-emulsified in water, are characterized first by their molecular weight, which is directly proportional to the viscosity of the pure oil. They are then characterized by the presence or absence of reactive functional groups, for example hydroxyl groups on the silicon atoms (silanol), their number, and their location on the molecular chain. For example, reactive oils with viscosities between 50 and 20,000 mPa·s, and in particular between 300 and 5,000 mPa·s, can be used, possessing at least one reactive functional group, preferably at least two, which can be located at the end of the chain.

[0228] Polymeric precursors reacting by polyaddition may include, for example, polymethylhydrosiloxane, vinylmethylsiloxane, vinyl-terminated polydimethylsiloxane (PDMS), in particular linear, vinyl-terminated diphenylsiloxane-dimethylsiloxane copolymers, hydride-terminated polydimethylsiloxanes, hydride-terminated polyphenylmethylsiloxanes, cyclic vinylmethylsiloxane, vinyl-MQ resin, trimethylsilyl-terminated polymethylhydrosiloxane, trimethylhydrosiloxane-terminated dimethylsiloxane copolymer, MQ resin hydride, and the like, as well as combinations thereof.

[0229] Polymeric precursors reacting by hydrolysis-polycondensation, whether silicone resins or silicone oils, may include, for example, poly(methylsilsesquioxanes), poly(propylsilsesquioxanes), poly(phenylsilsesquioxanes), polydimethylsiloxane (PDMS), polydimethylsiloxane (PDMS), terminated trimethylsilyl, polydimethylsiloxane (PDMS) terminated hydroxyl, polydimethylsiloxane (PDMS) terminated silanol, polyphenylsiloxane (PDMS) terminated silanol, diphenylsiloxane-dimethylsiloxane copolymer terminated silanol, poly(2-acetoxyethylsilsesquioxanes), organo-modified alkoxysilanes and their oligomers, and all similar macromolecules and mixtures thereof.

[0230] The organopolysiloxane material or polymer can also be obtained by crosslinking a mixture of one or more monomeric precursors and one or more polymeric precursors as described above, as well as one or more oligomeric precursors, which may be linear, branched, or cyclic. These oligomeric precursors have a lower molecular weight than the polymeric precursors. Polymeric and / or oligomeric precursors having more than two reactive functions as described above, advantageously much more than two, can be added to the mixture as a "co-binder" to promote a high crosslinking density of the organopolysiloxane polymer ultimately obtained.

[0231] Monomeric, oligomeric and / or polymeric precursors, in particular silicone resins, copolymerized or not with an organic polymer, play the role of polymeric binder in order to obtain the solid organopolysiloxane polymer combined with the thermoplastics of each layer.

[0232] Silicone oil-type organopolysiloxane precursors can be considered as additives if they are added in small quantities (generally between 0.1 and 5% dry) to the overall formula of a layer, independently of the other components for the formation of the solid organopolysiloxane polymer.

[0233] Crosslinking may require a catalyst:

[0234] - In the case of the crosslinking of organopolysiloxanes by hydrolysis- polycondensation, the formula may include a metallic catalyst, such as for example metal complexes based on platinum, tin, zinc, zirconium and cerium, in particular platinum-cyclovinylmethyl-silxane complexes, tin ethylhexanoate, zinc ethylhexanoate, zirconium ethylhexanoate, cerium ethylhexanoate, and tin dibutyl laurate.

[0235] - In the case of the crosslinking of organopolysiloxanes by hydrosylation, the addition a catalyst may be required: this could be for example platinum or a suitable platinum-based catalyst such as the Karstedt catalyst or the Ashbys catalyst.

[0236] A crosslinking agent, for example carrying Si-H bonds, may be present.

[0237] OTHER ARCHITECTURES

[0238] According to a particular embodiment, the coating comprises two intermediate layers (3b), at least one of which is a decorative layer. Advantageously, the layer(s) (3b) comprise several decorative layers, one (i) comprising one or more thermochromic pigment(s) and the other (j) comprising at least one temperature reference pigment composition.

[0239] Preferably, the intermediate layer(s) (3b) only partially cover the base layer (3a).

[0240] According to one embodiment, the topcoat (3c) consists of one or more silicone resins, and optionally: - of one or more charge(s) and / or - of one or more additive(s), and / or - of one or more coloring agent(s).

[0241] According to one embodiment, the coated heating element (1) further comprises a layer (3d) which will be the last layer of the coating (3) when present, consisting of:

[0242] - of a silicone elastomer obtained from at least one organopolysiloxane carrier of reactive vinyl functions (-CH=CH2) and at least one other organopolysiloxane bearing reactive silyl hydride (Si-H) functions, preferably in the presence of a metallic catalyst; and possibly:

[0243] - of one or more thermoplastic polymers, and / or

[0244] - of one or more additive(s), and / or

[0245] - of one or more coloring agent(s).

[0246] Organopolysiloxanes bearing reactive (3d) layer functions are precursors that react by crosslinking, which is a polyaddition (or hydrosilylation). This crosslinking occurs through a reaction between the reactive vinyl (-CH=CH2) functions present on one of the organopolysiloxanes and the reactive silyl hydride (Si-H) functions present on the other organopolysiloxane mixed with the first.

[0247] This crosslinking can be achieved by thermal activation, or chemical activation using a catalyst.

[0248] Advantageously, organopolysiloxanes bearing reactive functions of the (3c) layer are silicone oils.

[0249] Reactive functional groups are present on each organopolysiloxane, with at least one such group and two, three, or more such groups being possible, as far as the molecular structure allows. Silicone oils containing at least one reactive functional group are called "reactive oils." The reactive functional groups may be located either at the ends of the macromolecular chain (termination) or distributed along the chain.

[0250] The addition of a catalyst may be necessary for crosslinking: this may be, for example, platinum or a suitable platinum-based catalyst such as the Karstedt catalyst or the Ashbys catalyst.

[0251] Advantageously, the thermoplastic polymer(s) is / are selected from the group consisting of polyethersulfone (PES), polyphenylene ether sulfone (PPSU), polyamideimide (PAI), polyimide (PI), poly(phenylene oxide) (PPO), poly(arylene sulfide) (PAS), polyetherimide (PEI), and polybenzymidazole (PBI), liquid crystal polymers (LCP), polyphenylene sulfide (PPS), polyarylether ketone (PAEK) including polyether ketone (PEK), polyether ether ketone (PEEK), polyether ketone ketone (PEKK), polyether ether ketone ketone (PEEKK), polyether ketone ether ketone ketone (PEKEKK) and their mixtures.

[0252] By way of suitable examples of heterocyclic thermoplastic polymers according to the invention are polyetherimides (PEI), polyimides (PI), polyamideimides (PAI) and polybenzymidazole (PBI), or mixtures thereof.

[0253] Advantageously, the polyaryletherketone(s) (PAEK) is / are chosen from the group consisting of: polyetherketones (PEK), polyetheretherketone (PEEK), polyetherketoneketones (PEKK), polyetheretherketoneketones (PEEKK) and polyetherketoneetherketoneketones (PEKEKK), particularly preferably is / are PEEK.

[0254] The additives and coloring agents are as described above.

[0255] Advantageously, the thickness of the topcoat (3d) is from 0.1 pm to 10 pm, preferably from 0.5 pm to 5 pm, particularly preferably from 1 pm to 2 pm.

[0256] METALLIC SUBSTRATE

[0257] Advantageously, said metallic substrate (2), also called support, is a substrate of aluminum, stainless steel, cast iron or aluminum, iron, titanium or copper.

[0258] For the purposes of this invention, aluminium means a metal consisting of 100% aluminium or an aluminium alloy.

[0259] Advantageously, the metallic substrate (2) is an aluminum substrate, a stainless steel substrate, or a multilayer metallic substrate. The metallic substrate (2) can be a two-layer or three-layer substrate, these multilayers being obtained, for example, by co-lamination, by hot diffusion under load (solid state bonding), or by hot or cold impact bonding.

[0260] Preferably, the metallic substrate (2) comprises an alternation of layers of metal and / or metallic alloy.

[0261] According to one embodiment, the metallic substrate (2) is an aluminum alloy substrate, a stainless steel substrate or a multilayer metallic substrate whose face (2a) is made of aluminum alloy or stainless steel.

[0262] Preferably, the metallic substrate (2) is an aluminum substrate.

[0263] Advantageously, the thickness of the metallic substrate (2) is between 0.5 mm and 10 mm.

[0264] Advantageously, the face (2a) of the metallic substrate (2) has previously undergone a surface treatment to improve the adhesion of the coating to said substrate.

[0265] According to one embodiment, the surface of the face (2a) of the metallic substrate (2) has undergone a surface treatment, said surface treatment being an etching chemical, brushing, hydration, sandblasting, shot blasting, physicochemical treatment such as plasma, corona or laser, chemical activation or a combination of these different techniques.

[0266] Advantageously, the surface of the substrate (2a) onto which the coating (3) according to the invention is to be applied can be treated to increase its specific surface area; for an aluminum substrate, this treatment can be carried out by anodizing (creation of a tubular alumina structure), chemical etching, sandblasting, brushing, shot peening, or by adding material using a technology such as thermal spraying (flame, plasma, or arc spray). Other metallic substrates can also be polished, sandblasted, brushed, shot-blasted, or have material added using a technology such as thermal spraying (flame, plasma, or arc spray).

[0267] As examples of metallic substrates that can be used in the present invention, advantageous examples include substrates made of anodized or unanodized aluminum, optionally polished, brushed, sandblasted, shot-blasted or micro-beaded; substrates made of anodized or unanodized aluminum alloy, optionally polished, brushed, sandblasted or micro-beaded; substrates made of steel, optionally polished, brushed, sandblasted, shot-blasted or micro-beaded; substrates made of stainless steel, optionally polished, brushed, sandblasted or micro-beaded; substrates made of cast steel, aluminum or iron; and substrates made of copper, optionally hammered or polished.

[0268] Advantageously, the substrate can be selected from substrates comprising ferritic stainless steel / aluminum / austenitic stainless steel layers, substrates comprising stainless steel / aluminum / copper / aluminum / austenitic stainless steel layers, cast aluminum caps, aluminum or aluminum alloy caps lined with an outer stainless steel base, metallic co-laminated substrates, for example two-layer co-laminated substrates comprising a stainless steel layer (for example intended to form the inner face of the article) and an aluminum or aluminum alloy layer, anodized or not (for example intended to form the outer face of the article).

[0269] Advantageously, the mean arithmetic roughness Ra of the surface of the face (2a) of the metallic substrate (2) is greater than or equal to 1 pm.

[0270] The arithmetic mean roughness Ra is measured using a roughness tester according to ISO 4287. Ra represents the arithmetic mean of the deviations from the mean. Surface topography can be studied, in particular, with a profilometer with a probe equipped with a fine stylus fitted with a diamond tip, or with an optical metrology device such as the Altisurf®, in which a chromatic confocal sensor allows for non-contact measurement. The study of this surface topography makes it possible to define the arithmetic mean roughness Ra.

[0271] PROCEDURE

[0272] The invention also relates to a method for manufacturing a heating element coated (1) with a coating (3) for a household article according to the invention, characterized by the following steps:

[0273] a) a step of supplying a metallic substrate (2) comprising two opposite faces;

[0274] c) optionally, a treatment step of at least one face (2a) of the metallic substrate (2), to obtain a treated face (2a) promoting the adhesion of a primer layer (3a) on the support (2);

[0275] d) a step of applying layers (3a), (3b) and (3c) of the coating (3);

[0276] e) optionally a drying step between 50°C and 150°C after application of each of the layers (3a) (3b) and (3c);

[0277] f) optionally a cooking step of the element obtained in step d) or e) at a temperature between 250°C and 420°C

[0278] g) optionally, a step of applying the layer (3d) to the element obtained in step d), e) or f);

[0279] h) optionally a cooking step of the element obtained in step g) at a temperature between 250°C and 420°C.

[0280] The invention also relates to a method for manufacturing a household article comprising a heating element coated (1) with a coating (3) according to the invention, characterized by the following steps:

[0281] a) a step of supplying a metallic substrate (2) in the form of a substantially flat metallic substrate comprising two opposite faces or of a support (2) of convex or hollow shape defining an inner face (21) concave and an outer face (22) convex;

[0282] b) where appropriate, where a metallic substrate in the form of a substantially flat metallic substrate is provided in step (a), a shaping step of said substrate to give it the form of a support (2) of convex or hollow shape defining an inner face (21) concave and an outer face (22) convex, said step (b) being carried out either before step (a), or before step (d) of producing layers (3a), (3b) and (3c) of the coating (3), or after step (f) of baking and before the optional step (g) of producing layer (3d) or after step (g);

[0283] c) optionally, a treatment step of at least one face (2a) of the metallic substrate (2), to obtain a treated face (2a) promoting the adhesion of a primer layer (3a) on the support (2);

[0284] d) a step of applying layers (3a), (3b) and (3c) of the coating (3);

[0285] e) optionally a drying step between 50°C and 150°C after application of each of the layers (3a) (3b) and (3c);

[0286] f) optionally a cooking step of the element obtained in step d) or e) at a temperature between 250°C and 420°C

[0287] g) optionally, a step of applying the (3d) layer to the element obtained in step d), e) or f)

[0288] h) optionally a cooking step of the element obtained in step g) at a temperature between 250°C and 420°C.

[0289] Advantageously, in step d), the layer(s) (3a), (3b) and (3c) is / are applied by pad printing, electrostatic powder coating, spraying, screen printing, roller application or digital printing, preferably by spraying. Advantageously, the spraying is carried out in a solvent-based or aqueous phase.

[0290] Advantageously, in step g), the layer (3d) is applied by electrostatic powder coating, spray spraying, screen printing, gun, squeegee, coating cylinder, brush, roller application or digital printing, preferably by spraying.

[0291] According to an advantageous arrangement of the invention, the topcoat (3d) is applied to the coated substrate at a deposition rate of less than or equal to 5 g / m2, preferably between 0.1 and 2.5 g / m2, even more preferably between 0.2 and 2 g / m2.

[0292] Advantageously, the process according to the invention includes a crosslinking step g') of the topcoat (3d) subsequent to or simultaneous with step g).

[0293] According to one variant, the crosslinking of the topcoat (3d) can generally be activated by heat treatment, at a temperature between 50 and 400°C, preferably between 50 and 300°C, taking into account the maximum resistance of the substrate to heat.

[0294] Advantageously, the crosslinking (g') of the topcoat (3c) is carried out at a temperature of 300°C for a period of 10 min.

[0295] Advantageously, the higher the crosslinking temperature, the shorter the crosslinking time.

[0296] According to one embodiment, the crosslinking step g') does not require heat treatment, in particular because the support is hot at the time of step g).

[0297] Advantageously, the steps of the process according to the invention allow the metallic support (2) to be coated with a coating (3) formed by layers (3a), (3b) and (3c), optionally (3d). Generally, these layers are wet during their application. For the purposes of this invention, a wet layer means a layer comprising all or part of its solvents.

[0298] The shaping process is also called stamping.

[0299] When the shaping step precedes the application d) of the coating, the coating is preferably carried out by spraying.

[0300] When this shaping step is subsequent to the application d) of the coating, the coating is preferably carried out by screen printing or by roller.

[0301] ARTICLE

[0302] The invention also relates to a household article comprising a heating element coated according to the invention or capable of being obtained according to the process of the invention.

[0303] According to one embodiment, this household article is a cooking article or an electric cooking appliance and layer (3c) or layer (3d), when present, forms a cooking face.

[0304] In this case, layer (3c) is advantageously transparent.

[0305] In this case, the coloring agent of layer (3c) or layer (3d), when present, is advantageously glitter.

[0306] Advantageously, the culinary article (100) according to the invention is chosen from the group consisting of saucepan, frying pan, fondue or raclette pan, stockpot, wok, sauté pan, crepe pan, grill, plancha, pot, casserole dish, cooker or bread machine bowl, cooking mold, molds and baking trays, barbecue trays and grills, preparation bowls.

[0307] According to one embodiment, the cooking article (100) has a heating face (6) intended to be brought into contact with an external heating source, the heating face (6) being opposite the cooking face (5) intended to be brought into contact with the food during cooking.

[0308] According to another embodiment, this household article is a cooking article or electric cooking appliance and the layer (3c) or the layer (3d), when present, is intended to be brought into contact with a heating source.

[0309] The culinary article according to the present invention may in particular be a culinary article in which one of the two opposite faces of the substrate is an interior face, possibly concave, intended to be disposed on the side of food that may be introduced into or onto said article, and in which the other face of the substrate is an exterior face, possibly convex, intended to be disposed towards a heat source.

[0310] Advantageously, the electric cooking appliance (200) is chosen from the group consisting of electric crepe maker, electric raclette appliance, electric fondue appliance, electric grill, electric plancha, electric cooker, bread machine, electric pressure cooker, waffle makers, rice cookers and jam makers.

[0311] The electric cooking appliance (200) comprises a coated cooking element (1) according to the invention and a heating source (210) configured to heat said coated cooking element (1).

[0312] According to one embodiment, the household article according to the invention is a small household heating appliance.

[0313] This may be an iron and the coated heating element is the sole of the iron or a hair care article and the coated heating element is one of the heating plates of said article. EXAMPLES

[0314] The goals, aspects and advantages of the present invention will be better understood from the following description of a particular embodiment of the invention presented by way of non-limiting example.

[0315] Of course, the invention is in no way limited to the embodiment described and illustrated, which has been given only by way of example. Modifications remain possible, particularly with regard to the composition of the various elements or by substitution of technical equivalents, without departing from the scope of protection of the invention.

[0316] 1) Examples of implementation:

[0317] Raw materials: - PES resin • PolyEtherSulfone (PES) powder resin, micronized grade from SUMITOMO, polymer powder with a d50 between 11 and 15 pm. - Solvents: • propionamide - Reinforcement charges: • Alumina, • Silicon Carbide • Pyrogenated silica, • Colloidal silica • Colloidal alumina • Mica - Thickener: • 50% acrylic polymer solution in water • hydrogenated castor oil - Silicone resins: • Methylphenyl silicone resin, in flakes • Methyl silicone resin, in flakes - Alcohol solvent • dipropylene glycol butyl ether (DPNB), • MPG propylene glycol - Surfactant: • Fatty alcohol polyglycol ether - Anti-foaming agent • Mineral oil - Pigments: • Mica or glitter • Carbon black: - Silicone oil: • A: non-reactive • B: reactive - Other additives: • buffer agent • anionic ester in ethanol / water, wetting agent, • Aqueous dispersion of polydimethylsiloxane gum, surface tension agent

[0318] Examples of embodiments of a culinary article according to the invention:

[0319] On a flat aluminium disc (30 cm in diameter), previously degreased and sandblasted to obtain a roughness of 4 to 7 pm (Ra), a continuous layer 3a chosen from the base layer compositions (3al and 3a2) as described below is deposited by screen printing: Layers 3a#:

[0320] Layer 3al:

[0321] [Tables2] Material Nature % wet % in cured film Solvent DEMINERALIZED WATER 29.57 0.00 Solvent PROPIONAMIDE 22.18 0.00 Thermoplastic polymer PES 18.48 59.19 Wetting agent Fatty alcohol polyglycol ether 0.52 0.07 Acrylic thickener Acrylic polymer solution (50% in water) 5.48 1.95 Buffering agent Amino alcohol 1.05 0.00 Carbon Black Pigment 4.13 4.14 Antifoam Mineral Oil 1.24 0.20 Reinforcing Filler Colloidal Silica 4.13 4.01 Reinforcing Filler Colloidal Alumina 9.50 18.41 Reinforcing Filler Silicon Carbide 3.72 12.03 100.00 100 Layer 3a2#:

[0322] [Tables3] Material Nature % wet % in cured film Silicone resin Methyl or methylphenyl silicone resin 18.75 45.07 Solvent Alcohol Glycol ether 18.75 0.00 Thickener Hydrogenated castor oil 0.62 1.45 Reinforcing filler Mica 1.87 4.79 Reinforcing filler Fumed silica 1.25 3.20 Pigment Carbon black 3.75 2.97 Reinforcing filler Alumina 1.87 4.79 Wetting agent Fatty alcohol polyglycol ether 1.19 0.12 Solvent DEMINERALIZED WATER 14.56 0.00 Solvent PROPIONAMIDE 10.92 0.00 Thermoplastic polymer PES 10.92 27.66 Acrylic thickener 50% acrylic polymer solution in water 0.73 0.21 Buffering agent Amino alcohol 0.11 0.00 Spreading agent Anionic ester in ethanol / water 1.25 1.12 Solvent Alcohol Propylene glycol 5.94 0.00 Reinforcing filler Colloidal alumina 3.75 5.74 Reinforcing filler Colloidal silica 3.75 2.88 100.00 100

[0323] The thickness of this base layer 3a of the example is between 5 pm and 15 pm.

[0324] The substrate, onto which the continuous base coat 3a is applied as described above, is coated with a multilayer non-stick coating consisting of an intermediate layer 3b (5-15 pm) which is dried at 80°C and a top coat 3c (5-15 pm). The entire assembly is then heated to 300°C for approximately 10 minutes, meaning that the process comprises only one baking step after the deposition of the various layers. Layers 3b#:

[0325] The compositions of the intermediate layers 3b deposited by screen printing are as described below (layer 3b 1 and layer 3b2).

[0326] Layer 3b 1:

[0327] [Tables4] Material Nature % moisture % in film Solvent DEMINERALIZED WATER 33.63 0.00 Solvent PROPIONAMIDE 25.22 0.00 Thermoplastic polymer PES 21.02 79.52 Wetting agent Fatty alcohol polyglycol ether 0.59 0.09 Acrylic thickener 50% acrylic polymer solution in water 6.23 2.62 Buffering agent Amino alcohol 1.19 0.00 Pigment Carbon black 4.70 5.57 Defoamer Mineral oil 1.41 0.27 Reinforcing filler Colloidal silica 4.14 4.75 Reinforcing filler Mica 1.40 5.35 Pigment Glitter 0.48 1.83 100.00 100

[0328] Layer 3b2:

[0329] [Tables5] Material Nature % moisture content % in cured film Silicone resin Methyl or methylphenyl silicone resin 21.62 51.39 Solvent Alcohol Glycol ether 21.62 0.00 Thickener Hydrogenated castor oil 0.72 1.66 Reinforcing filler Mica 1.08 2.73 Reinforcing filler Fumed silica 1.44 3.65 Pigment Carbon black 4.32 3.39 Wetting agent Fatty alcohol polyglycol ether 1.08 0.11 Solvent DEMINERALIZED WATER 11.19 0.00 Solvent PROPIONAMIDE 8.40 0.00 Thermoplastic polymer PES 8.40 21.02 Acrylic thickener 50% acrylic polymer solution in water 0.56 0.16 Buffering agent Amino alcohol 0.09 0.00 Spreading agent Anionic ester in ethanol / water 1.44 1.28 Surfactant Surface Aqueous dispersion of polydimethylsiloxane gum 0.72 0.97 Solvent Alcohol Propylene glycol 6.49 0.00 Reinforcing filler Colloidal alumina 7.21 10.92 Reinforcing filler Colloidal silica 3.60 2.73 100.00 100

[0330] The compositions of the 3c finishing layers deposited by screen printing are as described below (layers 3c 1 to 3c4): Top coat (3c)

[0331] Layer 3cl:

[0332] [Tableauxô] Material Nature %wet % in baked film Solvent DEMINERALIZED WATER 39.4 0.00 Solvent PROPIONAMIDE 29.55 0.00 Thermoplastic polymer PES 24.62 91.15 Wetting agent Fatty alcohol polyglycol ether 0.69 0.10 Acrylic thickener 50% acrylic polymer solution in water 3.44 1.42 Buffering agent Amino alcohol 0.3 0.00 Silicone oil A 2.00 7.33 100 100

[0333] Layer 3c2:

[0334] [Tables?] Material Nature % moisture content % in cured film Silicone resin Methyl or methylphenyl silicone resin 30.00 70.62 Solvent Alcohol Glycol ether 39.60 0.00 Reinforcing filler Fumed silica 1.00 2.50 Thickener Hydrogenated castor oil 1.70 3.87 Wetting agent Fatty alcohol polyglycol ether 1.65 0.17 Solvent DEMINERALIZED WATER 8.54 0.00 Solvent PROPIONAMIDE 6.41 0.00 Thermoplastic polymer PES 6.41 15.89 Acrylic thickener 50% acrylic polymer solution in water 0.43 0.12 Buffering agent Amino alcohol 0.06 0.00 Spreading agent Anionic ester in ethanol / water 1.50 1.31 Surface tensioning agent Aqueous dispersion of polydimethylsiloxane gum 1.00 1.33 Silicone oil B 1.00 2.45 Silicone oil A 0.50 1.23 Pigment Glitter 0.20 0.50 100.00 100

[0335] Layer 3c3:

[0336] [Tables8] Natural material % moisture content % in cooked film Silicone resin Methyl or methyl-phenyl silicone resin 7.1 23.44 Solvent Alcohol Glycol ether 7.1 0.00 Thickener Hydrogenated castor oil 0.1 0.32 Reinforcing filler Fumed silica 0.2 0.70 Wetting agent Fatty alcohol polyglycol ether 0.4 0.06 Solvent Alcohol Propylene glycol 12.82 0.00 Spreading agent Anionic ester in ethanol / water 0.35 0.43 Defoamer Mineral oil 0.7 0.12 Solvent Demineralized water 27.3 0.00 Solvent Propionamide 20.48 0.00 Thermoplastic polymer PES 20.48 71.21 Wetting agent Fatty alcohol polyglycol ether 0.48 0.07 Acrylic thickener 50% acrylic polymer solution in water 1.39 0.54 Buffering agent Amino alcohol 0.2 0.00 Silicone oil A 0.7 2.41 Pigment Glitter 0.2 0.70 100 100

[0337] Layer 3c4:

[0338] [Tables9] Material Nature % moisture content % in cured film Silicone resin Methyl or methyl-phenethyl silicone resin 30.00 84.33 Solvent Alcohol Glycol ether 41.70 0.00 Thickener Hydrogenated castor oil 1.60 4.35 Reinforcing filler Fumed silica 1.00 2.99 Wetting agent Fatty alcohol polyglycol ether 1.50 0.18 Solvent Alcohol Propylene glycol 20.00 0.00 Spreading agent Anionic ester in ethanol / water 1.50 1.57 Surface tensioning agent, aqueous dispersion of polydimethylsiloxane gum 1.00 1.58, silicone oil B 1.00 2.93, silicone oil A 0.50 1.47, pigment, glitter 0.20 0.60 100.00 100

[0339] Examples of construction / architecture of heating elements according to the invention:

[0340] [TableauxlO] 1 2 3 Base coat al a2 al Intermediate coat bl b2 bl Top coat cl c2 c3

Claims

Demands

1. Coated heating element (1) for household appliances, comprising a metallic substrate (2) coated on at least one face (2a) with a coating (3) free of fluorocarbon resin and comprising at least the following layers, in this order from the metallic substrate (2): (3a) a primer layer consisting of polyethersulfone (PES) or a mixture of polyethersulfone (PES) and one or more silicone resins, and optionally: - one or more fillers and / or - one or more additives, and / or - one or more colorants (3b) one or more intermediate layer(s) consisting of polyethersulfone (PES) or a mixture of polyethersulfone (PES) and one or more silicone resins, and optionally: - one or more fillers, and / or - one or more additives, and / or - of one or more colouring agent(s) (3c) topcoat made of polyethersulfone (PES),or consisting of a mixture of polyethersulfone (PES) and one or more silicone resins, or consisting of one or more silicone resins, and optionally: - one or more fillers and / or - one or more additives, and / or - one or more coloring agents; it being understood that layer (3a), layer (3c) and at least one of the layers (3b) are different.

2. Coated heating element (1) according to claim 1, characterized in that layer (3a), layer (3c) and all layers (3b), when there are several, are all different.

3. Coated heating element (1) according to claim 1 or 2, characterized in that the PES content in the primer layer (3a) is less than the PES content in the layer(s) (3b).

4. Coated heating element (1) according to claim 3, characterized in that the PES content increases from the primer layer (3a) to the finishing layer (3c).

5. Coated heating element (1) according to any one of the preceding claims, characterized in that the PES content of the primer layer (3a) represents from 50% to less than 75% by weight of the primer layer (3a).

6. Coated heating element (1) according to any one of the preceding claims, characterized in that the PES content of the intermediate layer (3b) represents from 75% to less than 85% by weight of the intermediate layer (3b).

7. Coated heating element (1) according to any one of the preceding claims, characterized in that the PES content of the finishing layer (3c) represents from 85% to 98% by weight of the finishing layer (3c).

8. Coated heating element (1) according to any one of the preceding claims, characterized in that the thickness of each of the coating layers (3a), (3b) and (3c) is from 5 pm to 15 pm.

9. Coated heating element (1) according to any one of the preceding claims, characterized in that it further comprises a layer (3d) which shall be the last layer of the coating (3), when present, consisting of: - a silicone elastomer obtained from at least one organopolysiloxane bearing vinyl reactive functions (-CH=CH2) and at least one other organopolysiloxane bearing silyl hydride reactive functions (Si-H), preferably in the presence of a metal catalyst; and optionally: - one or more thermoplastic polymers, and / or - one or more additive(s), and / or - one or more coloring agent(s).

10. A method for manufacturing a household article comprising a heating element coated (1) with a coating (3) according to any one of the preceding claims characterized by the following steps: a) a step of supplying a metallic substrate (2) in the form of a substantially flat metallic substrate comprising two opposite faces or of a support (2) of convex or hollow shape defining an inner face (21) concave and an outer face (22) convex; (b) where appropriate, where a metallic substrate in the form of a substantially flat metallic substrate is provided in step (a), a shaping step of said substrate to give it the form of a support (2) of convex or hollow shape defining an inner face (21) concave and an outer face (22) convex, said step (b) being carried out either before step (a), or before step (d) of producing layers (3a), (3b) and (3c) of the coating (3), or after step (f) of baking and before the optional step (g) of producing layer (3d) or after step (g); (c) optionally, a treatment step of at least one face (2a) of the metallic substrate (2), to obtain a treated face (2a) promoting the adhesion of a primer layer (3a) to the support (2); d) a step of applying layers (3a), (3b) and (3c) of the coating (3);e) optionally a drying step between 50°C and 150°C after application of each of the layers (3a) (3b) and (3c); f) optionally a baking step of the element obtained in step d) or e) at a temperature between 250°C and 420°C; g) optionally, a step of applying layer (3d) to the element obtained in step d), e) or f); h) optionally a baking step of the element obtained in step g) at a temperature between 250°C and 420°C.

11. Household article comprising a coated heating element (1) according to any one of claims 1 to 9 or capable of being obtained according to claim 10.

12. Household article according to claim 11 characterized in that it is a cooking article or an electric cooking appliance and in that layer (3c) or layer (3d), when present, forms a cooking surface.

13. Household article according to claim 12, characterized in that the coloring agent of layer (3c) or layer (3d), when present, is glitter.

14. Household article according to claim 11, characterized in that it is a cooking article or electric cooking appliance and in that layer (3c) or layer (3d), when present, is intended to be brought into contact with a heating source.

15. Cooking article (100) according to any one of claims 12 to 14, selected from the group consisting of saucepan, frying pan, fondue or raclette pan, stockpot, wok, sauté pan, crepe pan, grill, griddle, pot, casserole dish, cooker or bread machine bowl, cooking mold, baking molds and trays, barbecue trays and grills, preparation bowls.

16. Electric cooking appliance (200) according to any one of claims 12 to 14, selected from the group consisting of electric crepe maker, electric raclette appliance, electric fondue appliance, electric grill, electric griddle, electric cooker, bread maker, electric pressure cooker, waffle makers, rice cookers and jam makers.

17. Household article according to claim 11 characterized in that it is a small household heating appliance.

18. Household article according to claim 17 characterized in that it is an iron and the coated heating element (1) is the sole of the iron or a hair care article and the coated heating element is one of the heating plates of said article.

Images