Fluorine-free pes / elastomeric silicone coating

Abstract

The invention relates to a coated heating element (1) for a domestic article, comprising a metal base (2) coated on at least one face (2a) by a coating (3) which does not contain fluorocarbon resins and which comprises at least the following layers in the following order from the metal base (2): (3a) a base coat comprising polyethersulfone (PES); (3b) one or more intermediate layers (3b) comprising polyethersulfone (PES) or a mixture of polyethersulfone (PES) and one or more silicones; (3c) a top coat consisting of an elastomeric silicone derived from at least one organopolysiloxane bearing vinyl reactive functions (-CH=CH2) and at least one other organopolysiloxane bearing hydrosilyl reactive functions (Si-H) or mercaptan reactive functions (S-H), and optionally: one or more thermoplastic polymers, and / or one or more additives, and / or one or more colorants; layer (3a) being different from at least one of layers (3b).

Description

Technical Field

[0001] This invention applies to household articles and heated or heatable non-stick coatings, particularly to cooking utensils and electric cooking equipment. Background Technology

[0002] Cookware coated with PTFE (polytetrafluoroethylene) is popular in the market because it allows for cooking with little or no added fat and is easy to clean. However, an inherent drawback of these coatings is their lower mechanical strength, especially at high temperatures. Another inherent disadvantage of PTFE is its ductility, which makes the coating susceptible to scratches, abrasions, and wear from metal utensils (spatulas, forks, spoons, hand mixers, etc.).

[0003] To address this problem, numerous technical solutions have been proposed, including enhancing the coating through hard fillers or by inserting inorganic or organic hard base coatings.

[0004] Significant improvements in abrasion resistance were indeed observed when using a base coat reinforced with organic or inorganic hard fillers, but metal impact marks were also observed when cooking foods such as pork chops or using metal spatulas.

[0005] In the case of inorganic hard substrates, such as those made of enamel or metal oxides, wear resistance is further improved, and impact problems are limited but not eliminated.

[0006] Organic polymer primers are also known. These primers can indeed significantly reduce or even eliminate the appearance of scratches. Therefore, this strategy is very useful. The polymers used are typically thermoplastic polymers with high heat resistance and high melting points, such as polyaryletherketones, especially oxy-1,4-phenylene-phenylene-oxy-1,4-phenylene-carbonyl-1,4-phenylene, or PEEK, or polyphenylene sulfide.

[0007] Pure silicone resins are described as relatively non-stick and resistant to temperatures above 220-230°C. However, they are considered to have poor adhesion to substrates.

[0008] Conversely, silicone-polyester resins are very common in the molding industry because they offer both non-stick properties and adhesion to the substrate, and are compatible with stamping processes. However, they degrade at temperatures above 230°C. In reality, cooking appliances are typically used in temperatures ranging from 50 to 250°C, and in the case of appliances with induction cooktops, temperatures reaching 300°C or even 350°C are not uncommon. Therefore, their use is incompatible with the operating temperatures of cooking appliances. Summary of the Invention

[0009] This invention relates to the technical problem of improving the non-stick properties of coatings with high thermomechanical properties.

[0010] The present invention also relates to a solution to the technical problem of replacing PTFE-type fluoropolymer-based coatings.

[0011] This invention proposes an alternative to the mainstream PTFE-based coating to achieve good coating resistance to mechanical wear, especially resistance to wear from kitchen utensils to cooking utensils, thereby improving their mechanical strength, especially their durability at high temperatures and / or their ease of cleaning, to extend the service life of the items.

[0012] definition In the context of this invention, the term "layer" should be understood as a continuous or discontinuous layer. A continuous layer (also called a monolithic layer) is a single, flat overlay that completely covers the surface to which it is deposited. A discontinuous layer (or non-monolithic layer) may comprise multiple portions that do not constitute a single unit.

[0013] "Base layer," "primer layer," "adhesive layer," or "adhesive primer layer" refers to all layers of the first layer applied directly to the support (which preferably adheres well to the support and imparts all the mechanical properties of the coating: hardness, scratch resistance), up to the last layer before the first intermediate layer, decorative layer, or topcoat (if the coating does not include an intermediate layer). The first layer of the coating is the primer layer.

[0014] An "intermediate layer" refers to a layer inserted between one or more base coats and one or more top coats. The one or more intermediate layers may be "decorative" or "furnishing layers." The one or more intermediate layers do not come into contact with food.

[0015] A "topcoat" or "coating" refers to one or more consecutive surface layers applied after one or more intermediate layers (if the coating includes one or more intermediate layers) or after one or more base coats. The final layer of the coating is the topcoat. Typically, at least the final topcoat, or even all topcoats, are transparent to allow the underlying layers to be seen, especially when the underlying layers are decorative layers. The one or more topcoats protect the underlying layers from mechanical damage and impart their non-stick properties to the coating. Preferably, in the case of cooking utensils or electric cooking equipment, the final topcoat comes into contact with the food.

[0016] "Decoration" or "decorative layer" refers to one or more continuous or discontinuous layers containing a pigment composition. Decoration can take the form of one or more patterns or one or more colors. The decoration is clearly visible to the naked eye at normal viewing distances of the item.

[0017] "Overlapping layers" refer to layers that are partially or completely stacked. These layers can be presented as partially overlapping patterns, such as concentric discs.

[0018] "Adjacent layers" refers to layers that do not overlap. These layers can be presented in the same or different, non-overlapping, preferably uniformly distributed pattern form.

[0019] A "temperature-referenced pigment composition" refers to a composition containing a pigment at a given temperature that indicates to the user that the optimal operating temperature has been reached. This indication is made by comparing the color of the thermochromic pigment composition with that of the temperature-referenced pigment composition. The optimal operating temperature is reached either when the colors are the same, or when the colors are visually very different.

[0020] The "temperature-referenced pigment composition" may comprise a pigment, which: - At optimal operating temperatures, it exhibits the same color as thermochromic pigment compositions. * Or because the pigment has the same color at room temperature as the thermochromic pigment composition at its optimal use temperature, and does not change with temperature. * Or, because the pigment has a different color at room temperature than the thermochromic pigment composition, the color evolves until it reaches the same color as the thermochromic pigment composition at its optimal use temperature. - At the optimal operating temperature, it has a color that is very different from that of thermochromic pigment compositions, regardless of whether the pigment changes with temperature.

[0021] The optimal operating temperature can be achieved when the color of the temperature-referenced pigment composition corresponds to the color indicated in the instruction manual of the household article including the coating of the present invention, or to the color indicated on the color chart provided to the user with the article.

[0022] The temperature-referenced pigment composition is either thermochromic or thermally stable.

[0023] Temperature-referenced pigment compositions can be, for example, cooking temperature-referenced pigment compositions or overheat risk indicator compositions.

[0024] In the context of this invention, the term "thermochromic semiconductor" should be understood as an inorganic or organic compound that exhibits a reversible color change upon increasing temperature. The gradual and reversible thermochromic properties of these semiconductor compounds are attributed to the reduction in the semiconductor band gap width due to material expansion. In practice, the periodicity of the anionic and cation lattices causes energy levels to cluster into energy bands. The highest energy band that is filled is called the valence band, and the lowest energy band that is empty is called the conduction band. Between these two bands lies a band gap. The color of a semiconductor material may originate from the presence of charge transfer, corresponding to an electron transitioning from the valence band to the conduction band on an atom, or typically from anionic orbitals to cation orbitals (interatomic photon absorption).

[0025] In the intended application areas of this invention, optimal conditions are achieved when the coating reaches a temperature suitable for cooking food, preferably between 100 and 250°C.

[0026] In the context of this invention, "thermochromic pigment or thermochromic pigment composition" should be understood as a pigment or pigment composition that changes color with temperature within a given temperature range, and this change is reversible. The color change is visible to the naked eye at normal viewing distances.

[0027] "Heat-stable pigments" refer to pigments that do not change color when subjected to temperature increases within a given temperature range, or pigments that exhibit such minute hue changes when subjected to temperature increases within a given temperature range that they are not visible to the naked eye at normal viewing distances.

[0028] Preferably, the color difference ΔE* of the heat-stabilized pigment between 25°C and 200°C is less than 10, where ΔE* is defined by the CIE1976 formula in the CIELAB color space: L1*, a1*, and b1* characterize the L*a*b values ​​of the compound at room temperature. L2*, a2*, and b2* characterize the L*a*b values ​​of the compound at 200°C.

[0029] "Same color" means that the user cannot distinguish them with the naked eye at normal viewing distance.

[0030] In the context of this invention, the term "cooking appliance" should be understood as an article that is cooked and heated by an external heating system, such as a frying pan, stew pot, wok, frying pan, or grill. A cooking appliance is capable of transferring heat energy provided by the external heating system to materials or food in contact with the article.

[0031] In the context of this invention, the term "electric cooking equipment" should be understood as a heated item having its own heating system, such as an electric crepe maker, an electric cheese grill, an electric cheese fondue, an electric grill, an electric flat griddle, an electric cooker, a bread maker, and a pressure electric cooking device.

[0032] "Coating" refers to the entirety of layers that adhere to and cover a metal substrate. The coating obtained according to the invention is advantageously solid, and "solid" refers to the property of a cohesive material that is insoluble in water, common solvents, food components such as aqueous or oily mixtures, even if the material can exhibit high hardness or high flexibility such as an elastomer.

[0033] In this invention, weight percentage is expressed as dry weight, i.e., without solvent.

[0034] Content of the invention The first subject of the present invention relates to a coated heating element (1) for household articles, comprising a metal substrate (2) having at least one side (2a) coated with a fluorocarbon-free coating (3), said coating comprising at least the following layers in the following order from the metal substrate (2): (3a) A base coating comprising polyethersulfone (PES). (3b) One or more intermediate layers (3b) comprising polyethersulfone (PES) or a mixture of polyethersulfone (PES) and one or more silicone resins; (3c) A topcoat, which consists of the following: - An elastomeric silicone derived from at least one organopolysiloxane having a vinyl reactive functional group (-CH=CH2) and at least another organopolysiloxane having a silane-hydrogen reactive functional group (Si-H) or a thiol reactive functional group (SH), and optionally: - One or more thermoplastic polymers, and / or - One or more additives, and / or - One or more colorants, The layer (3a) is different from at least one of the layers (3b).

[0035] Another subject of the present invention relates to a method for manufacturing a household article comprising a coated heating element (1) coated with a coating (3) according to the invention, characterized by the following steps: a) The step of providing a metal substrate (2) is in the form of a generally flat metal substrate having two opposite surfaces, or in the form of a convex or concave support (2) defining a concave inner surface (21) and a convex outer surface (22). b) Where applicable, when a metal substrate in the form of a generally flat metal substrate is provided in step (a), the step of shaping the substrate to give it the shape of a convex or concave support (2), the convex or concave support defining a concave inner surface (21) and a convex outer surface (22), the step (b) being performed either before step (a), or before step (d) of preparing layers (3a) and (3b) of coating (3), or after step (f) of baking and before step (g) of preparing the topcoat, or after step (g); c) Optionally, a step of treating at least one surface (2a) of the metal substrate (2) to obtain a treated surface (2a) to promote the adhesion of the base coating (3a) to the support (2); d) The steps of applying coating (3) to layers (3a) and (3b); e) Optionally, a drying step is performed between 50°C and 150°C after applying each layer (3a) (3b); f) Optionally, the element obtained in step d) or e) is calcined at a temperature between 250°C and 420°C; g) Applying a surface coating (3c) to the element obtained in step d), e), or f); h) Optionally, the element obtained in step g) is calcined at a temperature between 250°C and 420°C.

[0036] Another subject of the invention relates to a household article comprising a coated heating element (1) according to the invention or a coated heating element that can be obtained by the method according to the invention. Attached Figure Description

[0037] [ Figure 1 [A schematic diagram of the heating element according to the present invention, wherein layer (3b) is continuous and covers the entire layer (3a);] [ Figure 2 [A schematic diagram of the heating element according to the present invention, wherein layer (3b) does not cover the entire layer (3a) and forms a decoration;] [ Figure 3 [A schematic diagram of the heating element according to the present invention, wherein layer (3b) is composed of two decorations (i) and (j);] [ Figure 4 [Schematic diagram of pattern distribution. 4A = Adjacent non-overlapping patterns. 4B = Partially overlapping patterns. 4C = Overlapping patterns;] [ Figure 5 [Schematic diagram of a cooking utensil according to the present invention;] [ Figure 6 [Image: Schematic diagram of an electric cooking device according to the present invention.] Detailed Implementation

[0038] The first subject of the present invention relates to a coated heating element (1) for household articles, comprising a metal substrate (2) having at least one side (2a) coated with a fluorocarbon-free coating (3), said coating comprising at least the following layers in the following order from the metal substrate (2): (3a) A base coating comprising polyethersulfone (PES). (3b) One or more intermediate layers (3b) comprising polyethersulfone (PES) or a mixture of polyethersulfone (PES) and one or more silicone resins; (3c) A topcoat, which consists of the following: - An elastomeric silicone derived from at least one organopolysiloxane having a vinyl reactive functional group (-CH=CH2) and at least another organopolysiloxane having a silane-hydrogen reactive functional group (Si-H) or a thiol reactive functional group (SH), and optionally: - One or more thermoplastic polymers, and / or - One or more additives, and / or - One or more colorants; The layer (3a) is different from at least one of the layers (3b).

[0039] Advantageously, layers (3a), (3b) and (3c) form a coating (3) covering the metal substrate (2). The coating (3) has anti-stick properties and forms an anti-stick coating, which is particularly imparted by layer (3c).

[0040] Advantageously, one side of layer (3a) is in contact with the side (2a) of metal substrate (2).

[0041] When the household item is a cooking appliance or electric cooking device, the coated surface (2a) of the metal substrate (2) forms the cooking surface. In other words, the coating (3) according to the invention comes into contact with the food. Advantageously, one side of the surface coating (3c) comes into contact with the food, thereby forming the cooking surface (5).

[0042] The coating (3) according to the present invention is free of fluorocarbon resin, also known as fluoropolymer or fluoropolymer. In other words, the coating (3) is free of fluorocarbon resin. Therefore, the coating (3) does not contain or release perfluoroalkyl compounds and polyfluoroalkyl compounds.

[0043] Advantageously, the thickness of the one or more layers (3a) and (3b) is between 1 µm and 100 µm, preferably between 2 µm and 30 µm, and particularly preferably between 3 µm and 10 µm.

[0044] Advantageously, the thickness of layer (3c) is between 0.1 µm and 10 µm, preferably between 0.5 µm and 5 µm, and more preferably between 1 µm and 2 µm.

[0045] Layers (3a) and (3b) The one or more base coats (3a) and the one or more intermediate coats (3b) contain PES.

[0046] Advantageously, PES is micronized. PES can have a d50 of 5 µm to 20 µm, preferably 8 µm to 18 µm. In the context of this invention, the term "D50" refers to the maximum size of 50% of the particles in terms of quantity.

[0047] In the coating (3) according to the invention, there is at least one intermediate layer (3b). Advantageously, in this case, the at least one intermediate layer (3b) is different from at least one base coat (3a). More preferably, in this case, all intermediate layers (3b) are different from the one or more base coats (3a).

[0048] According to some embodiments, the PES content in the base layer (3a) is lower than the PES content in the one or more layers (3b).

[0049] Advantageously, the PES content increases from the base coat (a) to the last coat (3b).

[0050] Therefore, advantageously, the PES content of the primer (3a) is 50% to less than 75% of the weight of the primer (3a), preferably 55% to 70%.

[0051] Advantageously, the PES content of the one or more intermediate layers (3b) is 75% to 98% of the weight of the intermediate layer (3b).

[0052] Advantageously, the PES of the first intermediate layer (3b) accounts for 75% to less than 85% of the weight of the first layer (3b), preferably 75% to 80%.

[0053] Advantageously, the PES of the second intermediate layer (3b) accounts for 85% to 98% of the weight of the second layer (3b), preferably 85% to 95%.

[0054] It should be understood that the terms “first layer” and “second layer” refer to the order of intermediate layers starting from the base (2).

[0055] In these embodiments, advantageously, layers (3a) and (3b) comprise polyethersulfone (PES) and optionally include: - One or more thermoplastics different from PES, and / or - One or more fillers, and / or - One or more additives, and / or - One or more colorants.

[0056] In these embodiments, advantageously, layers (3a) and (3b) comprise polyethersulfone (PES) and one or more fillers.

[0057] In these embodiments, advantageously, the filler content decreases from the base coat (3a) to the last coat (3b).

[0058] According to other embodiments, the PES content in the base layer (3a) is higher than the PES content in the one or more layers (3b).

[0059] Advantageously, the PES content decreases from the base coat (3a) to the last coat (3b).

[0060] Therefore, advantageously, the PES of the primer (3a) accounts for 25% to 30% of the weight of the primer.

[0061] Advantageously, the PES of the one or more intermediate layers (3b) accounts for 15% to less than 25% of the weight of the intermediate layer.

[0062] Advantageously, the PES of the first intermediate layer (3b) accounts for 20% to less than 25% of the layer weight.

[0063] Advantageously, the PES of the second intermediate layer (3b) accounts for 10% to less than 20% of the layer weight, preferably 15% to less than 20%.

[0064] In these embodiments, advantageously, layers (3a) and (3b) comprise a mixture of polyethersulfone (PES) and one or more silicone resins, and optionally include: - One or more thermoplastics different from PES, and / or - One or more fillers, and / or - One or more additives, and / or - One or more colorants.

[0065] In these embodiments, advantageously, the silicone content increases from the base coat (3a) to the last layer (3b).

[0066] In these embodiments, advantageously, the content of PES decreases from the base coat (3a) to the last layer (3b), and the content of silicone resin increases from the base coat (3a) to the last layer (3b).

[0067] In these embodiments, advantageously, the (PES + silicone) content in layers (3a) and (3b) is 40% to 90% or 50% to 90% of the weight of each layer, preferably 60% to 90%, more preferably 70% to 90%.

[0068] These implementations are particularly suitable for situations where the heating element is shaped to give it a convex shape, such as a frying pan.

[0069] According to other embodiments, particularly where the coated heating element is stamped after the coating (3) is deposited and the coating (3) is subjected to high stress during the stamping step, the last layer (3b) comprises polyethersulfone (PES) and one or more silicone resins, and optionally includes: - One or more thermoplastics different from PES, and / or - One or more fillers, and / or - One or more additives, and / or - One or more colorants, The PES content accounts for 60% to 80% of the weight of the last layer (3b), the silicone resin content accounts for 5% to 30% of the weight of the last layer (3b), and the (PES + silicone resin) content accounts for 70% to 98% of the weight of the last layer (3b), preferably 80% to 98%, more preferably 90% to 98%.

[0070] Advantageously, the PES content of the primer layer (3a) is 50% to less than 75% by weight, preferably 55% to 70%. Advantageously, the PES content of the first intermediate layer (3b) is 75% to less than 85% by weight, preferably 75% to 80%.

[0071] The high PES content in layers (3a) and (3b) ensures good stampability under high stress.

[0072] Therefore, these implementations are particularly suitable for situations where the heating element is shaped to give it a concave shape, such as in a stew pot.

[0073] Layer (3c) The topcoat (3c) consists of the following: - An elastomeric silicone derived from at least one organopolysiloxane having a vinyl reactive functional group (-CH=CH2) and at least another organopolysiloxane having a silane-hydrogen reactive functional group (Si-H) or a thiol reactive functional group (SH), and optionally: - One or more thermoplastic polymers, and / or - One or more additives, and / or - One or more colorants.

[0074] The elastomeric silicone forming network of layer (3c) can be composed of a combination of four simple organosiloxane units called M, D, T and Q, depending on the degree to which silicon atoms are substituted with oxygen, as shown in the table below, where R is an organic substituent as described below.

[0075] Table 1 The precursors of the elastomers are organopolysiloxanes. These macromolecules are formed from the M, D, T and / or Q units described in the table, wherein R is independently alkyl, particularly methyl, or aryl, particularly phenyl, and Rs with different properties can coexist on the same macromolecule.

[0076] Organopolysiloxanes can be linear or slightly branched (mostly D-groups). Linear or slightly branched organopolysiloxanes are typically liquids at room temperature, have more or less high viscosity, and are referred to as silicone oils.

[0077] The organopolysiloxane with reactive functional groups in layer (3c) is a precursor for crosslinking via addition polymerization. This crosslinking occurs through a reaction between a vinyl reactive functional group (-CH=CH2) present on one organopolysiloxane and a silane-hydrogen reactive functional group (Si-H) or a thiol reactive functional group (SH) present on another organopolysiloxane mixed with the first.

[0078] The crosslinking can be carried out by thermal activation, UV irradiation activation, or chemical activation. Preferably, the crosslinking is carried out in the presence of a catalyst or free radical initiator.

[0079] According to one embodiment, when crosslinking is carried out by a reaction between a vinyl reactive functional group (-CH=CH2) present on one organopolysiloxane and a silane-hydrogen reactive functional group (Si-H) present on another organopolysiloxane mixed with the first, the reaction is preferably carried out in the presence of a metal catalyst, such as platinum or a suitable platinum-based catalyst such as a Karstedt catalyst or an Ashby catalyst.

[0080] According to one embodiment, when crosslinking is carried out via a reaction between a vinyl reactive functional group (-CH=CH2) present on one organopolysiloxane and a thiol reactive functional group (-SH) present on another organopolysiloxane mixed with the first, the reaction is preferably carried out in the presence of a free radical initiator. According to one embodiment, the free radical initiator may be thermally activated, such as 2,2′-azobis(2-methylpropanemidine) dihydrochloride (or V50). According to one embodiment, the free radical initiator may be UV-irradiated activated, such as Irgacure® 651 (2,2-dimethoxy-2-phenylacetophenone).

[0081] Advantageously, the organopolysiloxane with reactive functional groups in layer (3c) is a silicone oil.

[0082] Each organopolysiloxane contains at least one reactive functional group, and may contain two, three, or more, as long as the molecular structure allows. Silicone oils containing at least one reactive functional group are called "reactive oils." Reactive functional groups can be located at the ends of the macromolecular chains (end-capping) or distributed along the chain.

[0083] Additional thermoplastic polymers Advantageously, the one or more thermoplastic polymers are selected from aromatic thermoplastic polymers, such as polyaryletherketone (PAEK), polyarylethersulfone (PAES), polyarylether sulfide (PAS) or polyphenylene ether (PPO), liquid crystal polymers, heterocyclic thermoplastic polymers and mixtures thereof.

[0084] Heterocyclic thermoplastic polymers As heterocyclic thermoplastic polymers suitable for use in this invention, examples may be made of polyetherimide (PEI), polyimide (PI), polyamideimide (PAI), and polybenzimidazole (PBI) or mixtures thereof.

[0085] PAEK Advantageously, the one or more polyaryletherketones (PAEKs) are selected from: polyetherketones (PEKs), polyetheretherketones (PEEKs), polyetherketoneketones (PEKKs), polyetheretherketoneketones (PEEKKs), and polyetherketoneetherketoneketones (PEKEKKs), with PEEK being particularly preferred.

[0086] Advantageously, the properties of one or more thermoplastic polymers described in layers (3a), (3b) and (3c) may be the same or different.

[0087] Advantageously, the layer (3c) comprises one or more thermoplastic polymers, which preferably account for less than 15% of the weight of the layer, and more preferably less than 10%.

[0088] filler The filler in this invention can provide mechanical reinforcement and also provide hydrophobic properties, while improving the mechanical strength and thermal conductivity of the coating.

[0089] Fillers do more than just give coatings color, but they can also contribute to that.

[0090] The presence of fillers with excellent thermal conductivity can compensate for the low thermal conductivity of PAEK polymer.

[0091] Advantageously, the one or more fillers are selected from ceramic fillers (SiO2, etc.) and / or mineral fillers and / or metal fillers (Al2O3, TiO2, etc.) and / or silica and / or diamond particles.

[0092] Preferably, the one or more fillers are selected from metal oxides, metal carbides, metal nitrides, metal nitrides and mixtures thereof.

[0093] Advantageously, the metal is a transition metal, such as at least one element selected from B, Ni, Ti, Zr or Hf.

[0094] More preferably, the one or more fillers are selected from: - Fillers used for reinforcement: organic or inorganic hard fillers; inorganic hard fillers are preferably silicon carbide, alumina, zirconium oxide, graphite, ceramics, carbonates, hydrated alumina, aluminum trioxide or one or more metal oxides, graphite, graphene particles. - Other fillers used for reinforcement are selected from metal oxides: silica, mica, layered fillers, clays such as montmorillonite, sepiolite, gypsum, kaolinite and lithium saponite, zinc dioxide, quartz, zirconium phosphate, alumina, zirconium oxide, zinc oxide, copper oxide, and iron oxide. - Fillers selected from reinforcing fibers: glass fiber, carbon fiber, or aramid fiber; - A conductive filler comprising transition metal carbides and / or transition metal nitrides: characterized in that the transition metal is at least one element selected from B, Ni, Ti, Zr, or Hf. For example: cubic boron nitride, diamond particles, metal particles; - Layered fillers that can impart lubricating properties, such as clay, graphene, or graphite.

[0095] Among fillers combined with silicone resin, the preferred fillers are: - Reinforcing filler: silica or carbonate, with a filler content of at least 10-15% by weight and potentially up to 60% by weight. - Alumina, hydrated alumina, aluminum trihydride, - Silica (precipitated or vapor phase), d50 < 0.1 µm, BET specific surface area > 30 m² / g, preferably between 30 and 500 m² / g. - Or a mixture of quartz and silica, diatomaceous earth or ground quartz, titanium, mica, talc, kaolin, barium sulfate, quicklime, zinc oxide, expanded vermiculite, unexpanded vermiculite, calcium carbonate, etc.

[0096] More preferably, the one or more fillers are selected from alumina, silicon carbide, tungsten carbide, boron nitride, quartz, and mixtures thereof.

[0097] Advantageously, the filler present in the one or more base layers (3a) or the one or more optional intermediate layers (3b) is an inorganic hard filler, preferably an oxide, carbide, metal nitride, preferably alumina, silicon carbide or fumed silica.

[0098] Some inorganic hard fillers, such as silicon carbide, in addition to their mechanical reinforcing properties, also have the advantage of being conductive fillers, thus providing excellent thermal conductivity.

[0099] Adding this type of filler can improve cooking results, allowing heat to be transferred better from the metal substrate to the food in contact with the coating.

[0100] Advantageously, the average diameter d50 of the packing is between 0.1 and 50 µm, and even more advantageously between 5 and 15 µm.

[0101] Advantageously, when a layer contains filler, the proportion of filler is 0.5 to 30% by weight relative to the total dry weight of the layer after calcination, preferably 5 to 20% by weight.

[0102] Advantageously, the proportion of filler in layer (3a) is greater than 20% by weight, preferably greater than 30% by weight, relative to the total weight of the layer.

[0103] Advantageously, the proportions of the fillers in layers (3a) and (3b) can be the same or different.

[0104] Advantageously, the properties of the fillers in layers (3a) and (3b) can be the same or different.

[0105] additive Advantageously, the additive is selected from defoamers, dispersants, wetting agents, thickeners, pH adjusters, and reactive silicone oils.

[0106] The one or more defoamers are preferably selected from mineral oil, glycols, hydrocarbons, glycerides, ethylene oxide, and emulsified fatty acids.

[0107] The one or more surfactants are preferably selected from ethylene glycol ethers, ethoxylated fatty alcohols (excluding alkylphenol ethoxylates (APE)), and gemini surfactants.

[0108] The one or more dispersants are preferably selected from anionic dispersants such as fatty acid derivatives.

[0109] The one or more thickeners are preferably selected from acrylic-based or polyurethane-based copolymers, cellulose, and fumed silica.

[0110] The one or more pH adjusters are preferably selected from Brønsted bases: ammonia, amines (triethylamine, triethanolamine, etc.), hydroxides (sodium hydroxide, potassium hydroxide, etc.), and carbonates.

[0111] Advantageously, the proportion of additives in layer (3a) is less than 1% by weight relative to the total weight of the layer.

[0112] Advantageously, the proportion of additives in layer (3c) is less than 20% by weight relative to the total weight of the layer.

[0113] Colorant Advantageously, the one or more colorants are selected from thermochromic pigments, heat-stable pigments, flake pigments, preferably holographic flake pigments, and mixtures thereof.

[0114] Advantageously, the proportion of colorant in layers (3a), (3b) and (3c) is 0.5 to 50% by weight relative to the total dry weight of the layer after calcination.

[0115] Advantageously, the proportion of colorant in layers (3a) and (3b) is 10% to 40% relative to the total weight of the layer.

[0116] Advantageously, when present, the proportion of colorant in layer (3c) is less than 10% by weight relative to the total weight of the layer.

[0117] Advantageously, the proportions of colorants in layers (3a), (3b) and (3c) can be the same or different.

[0118] Advantageously, the properties of the colorants in layers (3a), (3b) and (3c) can be the same or different.

[0119] Advantageously, layer (3c) is transparent. In this case, if it contains colorants, these colorants are flake pigments.

[0120] Thermochromic Pigments Preferably, the one or more thermochromic pigments are selected from Bi2O3, Fe2O3, V2O5, WO3, CeO2, In2O3, and Y1. 84 Ca0. 16 Ti1. 84 V0. 16 O1. 84 AgI, (Bi 1-x A x (V) 1- yMy)O4, of which - x equals 0 or x is between 0.001 and 0.999, - y equals 0 or y is between 0.001 and 0.999. - A and M are selected from nitrogen, phosphorus, alkali metals, alkaline earth metals, transition metals, depleted metals, metalloids, or lanthanides. - A and M are different from each other.

[0121] It should be understood that A and M are different from each other, when: - A is an alkali metal, which can be selected from Li, Na, K, Rb, and Cs. - M is an alkali metal, which can be selected from Li, Na, K, Rb, and Cs. - A is an alkaline earth metal, which can be selected from Be, Mg, Ca, Sr, and Ba. - M is an alkaline earth metal, which can be selected from Be, Mg, Ca, Sr, and Ba. - A is a transition metal, which can be selected from Sc, Ti, Cr, Mn, Fe, Co, Ni, Cu, Y, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Ta, W, and Ir. - M is a transition metal, which can be selected from Sc, Ti, Cr, Mn, Fe, Co, Ni, Cu, Y, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Ta, W, and Ir. - A is a low-grade metal, which can be selected from Al, Zn, Ga, In, and Sn. - M is a low-grade metal, which can be selected from Al, Zn, Ga, In, and Sn. - A is a metalloid, which can be selected from B, Si, Ge, and Sb. - M is a metalloid, which can be selected from B, Si, Ge, and Sb. - A is a lanthanide element, which can be selected from La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu. - M is a lanthanide element, which can be selected from La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu.

[0122] Preferably, the different A and M are B and / or Mg.

[0123] Preferably, pigment (Bi) 1-x A x (V) 1- yMy)O4 exists as monoclinic scheelite crystals at room temperature.

[0124] Preferably, x and y are 0, i.e., pigment (Bi) 1-x A x (V) 1- yMy)O4 is bismuth vanadate (BiVO4). Advantageously, BiVO4, which has a monoclinic scheelite crystal structure at room temperature, is used.

[0125] Bismuth vanadate is a yellow inorganic compound with the chemical formula BiVO4, widely used for its coloring properties and non-toxicity. It is registered in the International Color Index Database as QI Pigment Yellow 184 and is particularly sold by Heubach (Vanadur®), BASF (Sicopal®), FERRO (Lysopac), or Bruchsaler Farbenfabrik (Brufasol®).

[0126] Heat-stabilized pigments Preferably, the one or more heat-stabilized pigments are selected from: - Rutile titanium yellow pigment, - Bismuth derivative yellow pigments, such as those selected from stabilized bismuth vanadate (Py 184 ), - Red pigments, such as those selected from perylene red (e.g., PR149, PR178 and PR224), iron oxide, - Bismuth halide orange pigment (PO) 85 ), - Bismuth vanadate orange pigment (PO) 86 ), - Tin-Titanium-Zinc Orange Pigment (PO) 82 ), - Cerium sulfide orange pigment (PO) 75 ;PO 78 ), - Chromium Antimony Titanium Gold Red Stone Type Orange-Yellow Pigment (PBr) 24 ), - Tin-zinc rutile orange-yellow pigment (Py 216 ), - Niobium sulfide zinc oxide orange-yellow pigment (Py 227 ), - Tin-niobium bioxide orange-yellow pigment, - Co3(PO4)2, - LiCoPO4, - CoAl2O4, - Cr2O3, - TiO2, - Black pigment PBk28 (copper chromium black spinel). - and its mixtures.

[0127] decorate According to one implementation, the one or more layers (3b) are continuous and cover the entire layer (3a) (see...). Figure 1 ).

[0128] According to another embodiment, the one or more layers (3b) do not cover the entire layer (3a) and form at least one decoration (see Figure 2 ).

[0129] Advantageously, the one or more layers (3b) constitute a plurality of decorations, one (i) comprising one or more thermochromic pigments, and another (j) comprising at least one temperature-referenced pigment composition (see Figure 3 ).

[0130] According to one implementation, the two decorations (i) and (j) are each presented as adjacent, non-overlapping patterns. For example, each decoration is represented by a pattern of different geometric shapes, evenly distributed across the entire surface and alternating with each other (see...). Figure 4 A).

[0131] According to another implementation, the two decorations (i) and (j) partially overlap. For example, each decoration is represented by a pattern of different geometries, evenly distributed across the entire surface and partially overlapping (see...). Figure 4 B).

[0132] Preferably, the two decorations (i) and (j) overlap, either because one decoration is a continuous layer and the other decoration covers it in a patterned form, or because the two decorations (i) and (j) are presented in an overlapping patterned form (see...). Figure 4 C).

[0133] flake pigments The flake pigments usable within the scope of this invention may be independently selected from: mica flake pigments, whether or not coated; silica flake pigments, whether or not coated; aluminum flake pigments, whether or not coated; iron oxide flake pigments, whether or not coated. Mica or silica flake pigments coated with titanium dioxide. The flake pigments usable within the scope of this invention may be processed to produce specific color effects.

[0134] Advantageously, the one or more flake pigments are particles selected from mica, aluminum, mica coated with titanium dioxide, or mixtures thereof.

[0135] Holographic flake pigment Advantageously, the one or more flake pigments are holographic flake pigments, which are mixtures of magnetizable particles and non-magnetizable particles.

[0136] Magnetizable particles can advantageously be particles containing at least one ferromagnetic metal. These magnetizable particles can be homogeneous, i.e., composed of the same material, or composite, i.e., these magnetizable particles have a core-shell structure, wherein the ferromagnetic metal is located in the core and / or shell of the particle. As examples of composite magnetizable particles, particularly noteworthy are mica flake pigments coated with Fe2O3 iron oxide or stainless steel fibers coated with sol-gel materials (as protection against corrosion during the coating process), or plastic flake pigments coated with Fe2O3 iron oxide, or flake pigments with a ferromagnetic metal core and a shell formed of plastic material or sol-gel material.

[0137] According to one embodiment, a portion of the magnetizable particles are oriented to form a three-dimensional decoration.

[0138] Advantageously, the mixture of magnetizable and non-magnetizable particles accounts for 1% to 5% of the weight of the layer, preferably 2% to 3%.

[0139] Advantageously, the percentage of non-magnetizable particles in the mixture of magnetizable and non-magnetizable particles is 15% to 40% relative to the total weight of the mixture of magnetizable and non-magnetizable particles.

[0140] Advantageously, the size D50 of the magnetizable particles is less than or equal to 23 µm.

[0141] In the context of this invention, the term "D50" refers to the maximum size of 50% of the particles in terms of quantity.

[0142] Advantageously, the size D90 of the non-magnetizable particle is 20% to 250% of the size D90 of the magnetizable particle.

[0143] In the context of this invention, the term "D90" refers to the maximum size in terms of the number of particles, which is 90% of the total.

[0144] Advantageously, magnetizable and / or non-magnetizable particles are colored on the surface.

[0145] Advantageously, the non-magnetizable particles are composed of mica, aluminum, or mica coated with titanium dioxide.

[0146] Advantageously, the magnetizable particles are composed of iron, iron oxide, iron-coated aluminum, or iron-coated mica, with the iron existing in the form of ferrite.

[0147] silicone resin In the text of this specification, the term "silicone" is used indiscriminately whether referring to silicone before or after crosslinking. In the text of this specification, the term "silicone" refers to an organopolysiloxane material. Crosslinking is the step of converting silicone into an insoluble material, for example, through addition polymerization, condensation polymerization, or dehydrogenation. Crosslinking begins with precursors, typically silicone oils or silicone resins, which crosslink to form a three-dimensional network of a material called silicone resin.

[0148] This crosslinking can be achieved through thermal activation or chemical activation with the aid of a catalyst, such as platinum.

[0149] Silicone resins can be obtained from precursors that are advantageously soluble in solvents or emulsions in water, such as crosslinkable oils or resins, particularly selected from: hydrides, silicone oils containing at least one vinyl group (-CH=CH2), silicone resins or silicone-polyester (copolymers) containing at least one alkoxy group (e.g., methoxy or ethoxy), and / or silicone resins or silicone-polyester (copolymers) containing at least one alkoxy group (especially ethoxy) or hydroxyl group, and mixtures thereof. These precursors have crosslinking capabilities to obtain silicone resins in an insoluble and substantially solid form.

[0150] Advantageously, these precursors are polymers or oligomers, either in the form of silicone oils with different degrees of branching, or in the form of silicone resins or silicone copolymers with different degrees of pre-crosslinking, such as silicone-polyester resins, silicone-alkyd resins, silicone-polyurethanes, silicone-epoxy resins, or mixtures of silicone oils, silicone resins, and silicone copolymers. Silicon atoms may be substituted with alkyl (especially methyl) or aryl (especially phenyl) groups or mixtures thereof. The oil or resin preferably contains one or more (two, three, or more) hydroxyl or alkoxy (especially methoxy, ethoxy, butoxy) functional groups as substituents for the silicon atoms.

[0151] Advantageously, the one or more silicone resins are obtained after crosslinking their precursors (i.e., after crosslinking) and are selected from methyl silicone resins and / or phenyl silicone resins and / or methyl-phenyl-silicone resins, methyl silicone-polyester resins (copolymers), phenyl silicone-polyester resins (copolymers), methyl-phenyl silicone-polyester resins (copolymers), silicone-alkyd resins (copolymers), modified silicone resins, and mixtures thereof.

[0152] Advantageously, the one or more silicone resins are selected from methyl silicone resins and / or phenyl silicone resins and / or methyl-phenyl-silicone resins, methyl silicone-polyester resins (copolymers), phenyl silicone-polyester resins (copolymers), methyl-phenyl silicone-polyester resins (copolymers), silicone-alkyd resins (copolymers), modified silicone resins, and mixtures thereof.

[0153] Silicone resins can be obtained from precursors, particularly selected from: hydrides, silicone resins containing at least one vinyl group (-CH=CH2), silicone-polyester resins (copolymers) containing at least one methoxy group, and / or silicone-polyester resins (copolymers) containing at least one ethoxy group, and mixtures thereof.

[0154] The silicone resin forms a network that can be composed of a combination of four simple organosiloxane units called M, D, T, and Q, depending on the degree to which silicon atoms are substituted with oxygen, as shown in the table below, where R is an organic substituent as described below.

[0155] Table 2 Organopolysiloxane materials or polymers are obtained by crosslinking from monomers or polymerization precursors, or intermediately from oligomeric precursors. Organopolysiloxanes can also be obtained from mixtures of these different types of precursors. The crosslinking density is higher when the network contains more T and Q units than D. The distribution among M, D, T, and Q units depends on the chemical structure of the precursor, particularly the distribution of M, D, T, and Q units within the precursor.

[0156] The polymerization precursors are organopolysiloxanes. These macromolecules are formed from the M, D, T and / or Q units described in the table, wherein R is independently alkyl, particularly methyl, or aryl, particularly phenyl, and Rs with different properties can coexist on the same macromolecule.

[0157] Organopolysiloxanes can be linear or slightly branched (mostly D-groups), or branched or highly branched (mostly T and Q-groups). Linear or slightly branched organopolysiloxanes are typically liquids at room temperature, have more or less high viscosity, and are referred to as silicone oils. Branched or highly branched (pre-crosslinked) organopolysiloxanes form large molecular-scale networks and are referred to as silicone resins. At room temperature, the resins are essentially solid, or in liquid form (especially when they have sufficiently low molecular weight), in solution in a solvent, or in aqueous emulsion form. They can be copolymerized with silicone-free organic polymers or oligomers, particularly selected from polyesters, acrylic resins, alkyd resins, polyurethanes, and epoxy resins.

[0158] When crosslinking is a hydrolysis-condensation process, it occurs via reactive functional groups, such as hydroxyl or alkoxy groups (especially methoxy, ethoxy, or butoxy), present on organopolysiloxanes.

[0159] When crosslinking is an addition polymerization (or hydrosilylation): it proceeds through a reaction between a vinyl reactive functional group (-CH=CH2) present on one organopolysiloxane and a silane-hydrogen reactive functional group (Si-H) present on another organopolysiloxane mixed with the first.

[0160] All of these reactive functional groups are present on each organopolysiloxane at least one, and may be two, three or more... as long as the molecular structure allows. Silicone oils containing at least one reactive functional group are called "reactive oils". Reactive functional groups may be located at the ends of the macromolecular chains (end-capping) or distributed along the chains.

[0161] Silicone-polyester resins particularly have silicone / polyester mass ratios of, for example, 90 / 10, 80 / 20, 70 / 30, 60 / 40, 50 / 50, 40 / 50, 30 / 70, 20 / 80, and 10 / 90, advantageously between 80 / 20 and 50 / 50.

[0162] Linear PDMS silicone oils, in pure or pre-emulsified water, are first characterized by their molecular weight, which is a direct functionally increasing function of the viscosity of the pure oil. They are then characterized by the presence, number, and position of reactive functional groups (e.g., hydroxyl groups on silicon atoms (silanols)). For example, reactive oils with viscosities from 50 to 20,000 mPa·s, particularly 300 to 5,000 mPa·s, can be used, possessing at least one reactive functional group, preferably at least two, which may be located at the chain ends.

[0163] Polymer precursors via addition polymerization reactions may include, for example, polymethylhydrosiloxanes, vinylmethylsiloxanes, particularly vinyl-terminated linear polydimethylsiloxanes (PDMS), vinyl-terminated diphenylsiloxane-dimethylsiloxane copolymers, hydride-terminated polydimethylsiloxanes, hydride-terminated polyphenylmethylsiloxanes, cyclic vinylmethylsiloxanes, vinyl-MQ resins, trimethylsilyl-terminated polymethylhydrosiloxanes, trimethylsiloxane-terminated methylhydrosiloxane and dimethylsiloxane copolymers, MQ resin hydrides, and combinations thereof.

[0164] Polymerization precursors via hydrolysis-condensation reactions, whether silicone resins or silicone oils, may include, for example, poly(methylsilsesquioxane), poly(propylsilsesquioxane), poly(phenylsilsesquioxane), polydimethylsiloxane (PDMS), trimethylsilyl-terminated polydimethylsiloxane (PDMS), hydroxyl-terminated polydimethylsiloxane (PDMS), silanol-terminated polydimethylsiloxane (PDMS), silanol-terminated polyphenylsiloxane (PDMS), silanol-terminated diphenylsiloxane-dimethylsiloxane copolymers, poly(2-acetoxyethylsilsesquioxane), organically modified alkoxysilanes and their oligomers, and all similar macromolecules and mixtures thereof.

[0165] Organopolysiloxane materials or polymers can also be obtained by crosslinking one or more monomeric precursors with one or more polymeric precursors as described above, and one or more oligomeric precursors that may be linear, branched, or cyclic. These oligomeric precursors have lower molecular weights than the polymeric precursors. Polymeric and / or oligomeric precursors with more than two, advantageously far more than two, reactive functional groups as described above can be added to the mixture in the form of a "co-binder" to promote a high crosslinking density in the final organopolysiloxane polymer.

[0166] Monomers, oligomers, and / or polymeric precursors, particularly silicone resins, whether or not copolymerized with organic polymers, act as polymeric binders to obtain solid organopolysiloxane polymers bonded to each layer of thermoplastic plastic.

[0167] Silicone oil-type organopolysiloxane precursors can be considered as additives, independent of other components used to form solid organopolysiloxane polymers, if added in small amounts (typically 0.1% to 5% in the dry state) to the entire formulation of a single layer.

[0168] Crosslinking may require a catalyst: - In the case of crosslinking organopolysiloxanes via hydrolysis-condensation, the formulation may contain metal catalysts, such as metal complexes based on platinum, tin, zinc, zirconium and cerium, particularly platinum-cyclovinylmethylsiloxane complexes, tin ethylhexanoate, zinc ethylhexanoate, zirconium ethylhexanoate, cerium ethylhexanoate and dibutyltin dilaurate.

[0169] - In the case of crosslinking organopolysiloxanes by hydrogenation silanization, a catalyst may need to be added: for example, platinum or a suitable platinum-based catalyst such as Karstedt catalyst or Ashby catalyst.

[0170] Crosslinking agents, such as those with Si-H bonds, may be present.

[0171] Metal substrate Advantageously, the metal substrate (2), also known as the support, is an aluminum, stainless steel, cast iron, or cast aluminum, iron, titanium, or copper substrate.

[0172] In the context of this invention, aluminum is understood to be a metal or aluminum alloy that is 100% aluminum.

[0173] Advantageously, the metal substrate (2) is an aluminum, stainless steel, or multilayer metal substrate. The metal substrate (2) can be a two-layer or three-layer substrate, which can be obtained, for example, by co-rolling, hot-press diffusion bonding (solid state bonding), or hot or cold impact bonding.

[0174] Preferably, the metal substrate (2) comprises alternating layers of metal and / or metal alloy.

[0175] According to one embodiment, the metal substrate (2) is an aluminum alloy, a stainless steel substrate, or a multilayer metal substrate, the surface (2a) of which is an aluminum alloy or stainless steel.

[0176] Preferably, the metal substrate (2) is an aluminum substrate.

[0177] Advantageously, the thickness of the metal substrate (2) is between 0.5 mm and 10 mm.

[0178] Advantageously, the surface (2a) of the metal substrate (2) has been pre-treated to improve the adhesion of the coating to the substrate.

[0179] According to one embodiment, the surface of the face (2a) of the metal substrate (2) has been surface treated, said surface treatment being chemical etching, brushing, hydration, sandblasting, shot peening, plasma or corona or laser physicochemical treatment, chemical activation or a combination of these different techniques.

[0180] Advantageously, the substrate surface (2a) to which the coating (3) according to the invention is to be applied can be treated to increase its specific surface area; for aluminum substrates, this treatment can be carried out by anodizing (producing a tubular alumina structure), chemical etching, sandblasting, brushing, shot peening, or by adding materials through techniques such as thermal spraying (flame, plasma, or arc spraying). Other metal substrates can also be polished, sandblasted, brushed, microbeaded, or by adding materials through techniques such as thermal spraying (flame, plasma, or arc spraying).

[0181] As metal substrates that can be used in this invention, the following can be advantageously mentioned: anodized or non-anodized aluminum substrates, optionally polished, brushed, sandblasted, shot-peened, or microbeaded; anodized or non-anodized aluminum alloy substrates, optionally polished, brushed, sandblasted, or microbeaded; steel substrates optionally polished, brushed, sandblasted, shot-peened, or microbeaded; stainless steel substrates optionally polished, brushed, sandblasted, or microbeaded; cast steel, cast aluminum, or cast iron substrates; and copper substrates optionally hammered or polished.

[0182] Advantageously, the substrate can be selected from substrates including ferritic stainless steel / aluminum / austenitic stainless steel layers, substrates including stainless steel / aluminum / copper / aluminum / austenitic stainless steel layers, cast aluminum caps, aluminum or aluminum alloy caps with stainless steel outer bottoms, metal co-rolled substrates, such as bilayer co-rolled substrates including stainless steel layers (e.g. forming the inner surface of the article) and aluminum or aluminum alloy layers (anodized or non-anodized, e.g. forming the outer surface of the article).

[0183] Advantageously, the arithmetic mean roughness Ra of the surface of the metal substrate (2) (2a) is greater than or equal to 1 µm.

[0184] The arithmetic mean roughness Ra is measured using a roughness meter according to ISO 4287 standard. Ra represents the arithmetic mean of the absolute values ​​of the deviations. Surface topography can be studied, in particular, using a profilometer equipped with a fine stylus with a diamond tip, or using optical metrology equipment such as Altisurf®, where a color confocal sensor allows for non-contact measurement. This study of surface topography can determine the arithmetic mean roughness Ra.

[0185] method The present invention also relates to a method for manufacturing a coated heating element (1) coated with a coating (3) according to the invention for use in household articles, characterized by the following steps: a) Providing a metal substrate comprising two opposite sides (2); c) Optionally, a step of treating at least one surface (2a) of the metal substrate (2) to obtain a treated surface (2a) to promote the adhesion of the base coating (3a) to the support (2); d) The steps of applying coating (3) to layer (3a) and optionally (3b); e) Optionally, a drying step is performed between 50°C and 150°C after applying each of the layers (3a) and (3b); f) Optionally, the element obtained in step d) or e) is calcined at a temperature between 250°C and 420°C; g) Applying a surface coating (3c) to the element obtained in step d), e), or f); h) Optionally, the element obtained in step g) is calcined at a temperature between 250°C and 420°C.

[0186] The present invention also relates to a method for manufacturing household articles comprising a coated heating element (1) coated with a coating (3) according to the present invention, characterized by the following steps: a) The step of providing a metal substrate (2) is in the form of a generally flat metal substrate having two opposite surfaces, or in the form of a convex or concave support (2) defining a concave inner surface (21) and a convex outer surface (22). b) Where applicable, when a metal substrate in the form of a generally flat metal substrate is provided in step (a), the step of shaping the substrate to give it the shape of a convex or concave support (2), the convex or concave support defining a concave inner surface (21) and a convex outer surface (22), the step (b) being performed either before step (a), or before step (d) of preparing layers (3a) and (3b) of coating (3), or after step (f) of baking and before step (g) of preparing the topcoat, or after step (g); c) Optionally, a step of treating at least one surface (2a) of the metal substrate (2) to obtain a treated surface (2a) to promote the adhesion of the base coating (3a) to the support (2); d) The steps of applying coating (3) to layer (3a) and optionally (3b); e) Optionally, a drying step is performed between 50°C and 150°C after applying each of the layers (3a) and (3b); f) Optionally, the element obtained in step d) or e) is calcined at a temperature between 250°C and 420°C; g) Applying a surface coating (3c) to the element obtained in step d), e), or f); h) Optionally, the element obtained in step g) is calcined at a temperature between 250°C and 420°C.

[0187] Advantageously, in step d), the one or more layers (3a) and (3b) are applied by pad printing, electrostatic spraying, spraying, screen printing, roller coating or digital printing, preferably by spraying. Advantageously, the spraying is carried out in a solvent phase or an aqueous phase.

[0188] Advantageously, in step g), the topcoat (3c) is applied by electrostatic spraying, spraying, screen printing, spray gun, doctor blade, coating roller, brush, roller coating or digital printing, preferably by spraying.

[0189] According to an advantageous arrangement of the invention, the topcoat (3c) is applied to the coated support at a deposition rate of less than or equal to 5 g / m², preferably between 0.1 and 2.5 g / m², more preferably between 0.2 and 2 g / m².

[0190] Advantageously, the method according to the invention includes a step g' of crosslinking the surface coating (3c) after or simultaneously with step g).

[0191] According to one variant, the crosslinking of the layer (3c) composition can typically be activated, for example, by heat treatment at a temperature between 50 and 400°C, preferably between 50 and 300°C, while obviously taking into account the maximum heat resistance of the support.

[0192] Advantageously, the crosslinking (g') of the topcoat (3c) varnish is carried out at a temperature of 300°C for 10 minutes.

[0193] Advantageously, the higher the crosslinking temperature, the shorter the crosslinking time.

[0194] According to one embodiment, the crosslinking step g') does not require heat treatment, especially since the support is hot during step g).

[0195] According to one embodiment, when at least one of the organopolysiloxanes of layer (3c) contains a thiol reactive functional group (SH), the crosslinking step g') can be carried out under UV irradiation using a free radical initiator activated by UV irradiation, such as Irgacure® 651 (2,2-dimethoxy-2-phenylacetophenone).

[0196] The method may also include an additional step g'') of crosslinking the composition applied in step g) by UV irradiation.

[0197] Advantageously, the steps of the method according to the invention allow the metal support (2) to be coated with a coating (3) formed of layers (3a), optionally (3b) and (3c). Typically, these layers are wet when applied. In the sense of the invention, a wet layer means a layer containing all or part of its solvent.

[0198] Advantageously, the topcoat (3c) is a surface layer, a thin layer, a protective layer, a hard layer, a smooth layer, a gloss layer, and a transparent layer.

[0199] In the context of this invention, the topcoat (3c) has, for example, a generally uniform thickness of less than or equal to 10 µm, preferably less than 5 µm.

[0200] The thickness of the topcoat (3c) is advantageously between 0.1 µm and 10 µm, preferably between 0.5 µm and 5 µm, and more preferably between 1 µm and 2 µm.

[0201] According to one variant, multiple layers can be deposited on top of each other (3c).

[0202] Layer (3c) is obtained from a composition that is liquid when applied. The viscosity of the layer (3c) composition can be adjusted by diluting it with a solvent according to the deposition method used.

[0203] The composition of layer (3c) may contain a solvent. Advantageously, when the composition of layer (3c) contains at least one organopolysiloxane with a silane-hydrogen reactive functional group (Si-H), the solvent is an aliphatic solvent. Advantageously, when the composition of layer (3c) contains at least one organopolysiloxane with a thiol reactive functional group (SH), the solvent is an aliphatic solvent or an alcohol solvent. Advantageously, the aliphatic solvent is selected from linear or cyclic aliphatic hydrocarbons having a carbon number between 5 and 10, and mixtures thereof.

[0204] Therefore, the composition of layer (3c) may contain a solvent in an amount greater than or equal to 40%, preferably greater than or equal to 50%, particularly preferably greater than or equal to 60% by weight, relative to the weight of the liquid composition used for layer (3c).

[0205] Surprisingly, the composition for the layer (3c) containing a very high solvent content makes it possible to obtain a layer (3c) that has a very thin and uniform thickness after crosslinking, and enables the coating (3) applied to the surface (2a) of the support (2) of the heating element (1) to have anti-stick properties or improve its anti-stick properties.

[0206] Particularly advantageously, the solvent content of the composition used for layer (3c) is greater than or equal to 70% or 80% by weight, relative to the weight of the liquid composition used for layer (3c).

[0207] Extremely advantageously, the solvent content of the composition used for layer (3c) is 70% to 90% or 80% to 90% by weight, relative to the weight of the liquid composition used for layer (3c).

[0208] Forming is also known as stamping.

[0209] When the forming step is performed before the application of the coating (d), the coating is preferably applied by spraying.

[0210] When this forming step is performed after the application of coating (d), the coating is preferably performed by screen printing or by rollers.

[0211] thing The present invention also relates to a household article comprising a coated heating element according to the invention or a coated heating element obtainable by the method of the invention.

[0212] According to one embodiment, the household item is a cooking appliance or electric cooking device, and layer (3c) forms a cooking surface.

[0213] In this case, layer (3c) is advantageously transparent.

[0214] In this case, the colorant of layer (3c) is advantageously a flake pigment.

[0215] Advantageously, the cooking utensil (100) according to the invention is selected from: stew pot, frying pan, small pot or long-handled frying pan for cheese fondue or cheese gratin, double-handled saucepan, frying pan, wok, crepe pan, grill, flat baking pan, deep pot, casserole, cookware liner or bread machine liner, cooking mold, pastry mold and baking pan, barbecue grill and grill rack, cooking bowl.

[0216] According to one embodiment, the cooking appliance (100) includes a heating surface (6) that is in contact with an external heat source, the heating surface (6) being opposite to a cooking surface (5) that is in contact with food during cooking.

[0217] According to some implementations, layer (3c) is in contact with a heat source.

[0218] The cooking appliance according to the invention can be, in particular, a cooking appliance in which one of the two opposite sides of the base is an inner surface, optionally concave, disposed on the side of food that may be introduced into or onto the appliance, and the other side of the base is an outer surface, optionally convex, disposed toward a heat source.

[0219] Advantageously, the electric cooking equipment (200) is selected from: electric crepe makers, electric cheese grills, electric cheese fondues, electric grills, electric flat griddles, electric cookers, bread makers, pressure electric cooking equipment, waffle makers, rice cookers and jam makers.

[0220] The electric cooking appliance (200) includes a coated heating element (1) according to the invention and a heat source (210) configured to heat the coated heating element (1).

[0221] According to one embodiment, the household item according to the invention is a small heating household appliance.

[0222] It can be an iron, and the coated heating element is the soleplate of the iron; or a hair care product, and the coated heating element is one of the heating plates of the product.

[0223] Example The objects, aspects and advantages of the invention will be better understood through the following description of specific embodiments of the invention (given as non-limiting examples).

[0224] Of course, the present invention is by no means limited to the embodiments described and shown, which are given by way of example only. Modifications are possible, particularly in terms of the composition of various elements or by substitution with technical equivalents, without departing from the scope of protection of the present invention.

[0225] raw material: - PES resin Polyethersulfone (PES) powder resin, micronized grade from SUMITOMO, polymer powder, d50 between 11 and 15 µm.

[0226] - Solvent: propionamide - Reinforcing filler: Alumina Silicon carbide, Fumed silica, Colloidal silica, Colloidal alumina mica - Thickener: A 50% solution of acrylic polymer in water. Hydrogenated castor oil - Silicone resin: Methyl-phenyl silicone resin, in sheet form. Methyl silicone resin, in sheet form - Alcohol solvent: Dipropylene glycol butyl ether (DPNB) Propylene glycol methyl ether (MPG) - Surfactants: Fatty alcohol polyethylene glycol ether - Defoamer: mineral oil - Pigment: Mica or flake pigments, carbon black - Silicone oil: A: Non-reactive. B: Reactivity - Other additives: Buffer, Anionic esters in ethanol / water, wetting agents. Aqueous dispersions of polydimethylsiloxane gels, surface tension agents Embodiments of the cooking appliance according to the present invention: On a flat aluminum disk (30 cm in diameter) that has been pre-degreased and sandblasted to obtain a roughness of 4 to 7 µm (Ra), a continuous layer 3a selected from the undercoating compositions (3a1 and 3a2) described below is deposited by screen printing: Layer 3a: Layer 3a1: Table 3 Layer 3a2: Table 4 The thickness of the base coat 3a in this example is between 5 µm and 15 µm.

[0227] A substrate on which the continuous undercoat 3a as described above was applied was coated with a multilayer anti-stick coating consisting of a first intermediate layer 3ba (5-15 µm) dried at 80°C and a second intermediate layer 3bb (5-15 µm). The entire substrate was then heated at approximately 300°C for approximately 10 minutes, meaning the method involves only one calcination step after the deposition of the different layers.

[0228] Layer 3ba: The composition of the intermediate layer 3ba deposited by screen printing is as follows (layer 3ba1 and layer 3ba2).

[0229] Layer 3ba1: Table 5 Layer 3ba2: Table 6 The composition of the intermediate layer 3bb deposited by screen printing is as follows (layers 3bb1 to 3bb3): Layer (3bb) Layer 3bb1: Table 7 Layer 3bb2: Table 8 Layer 3bb3: Table 9 Layer (3c1): Layer (3c1) is obtained by crosslinking the following composition, expressed as relative parts by dry weight: - Organopolysiloxanes with vinyl reactive functional groups (-CH=CH2): 100 parts, - Another organopolysiloxane with a silane-hydrogen reactive functional group (Si-H): 8 parts, and - Metal catalyst: 6 parts.

[0230] The above-mentioned dry composition is mixed with a solvent to obtain a dry extract with a mass content of about 10% to 20%.

[0231] After applying the layer (3c1), place the whole unit in an oven at 300°C for 30 to 45 minutes to dry and then crosslink the layer (3c1), and then cool the disc.

[0232] Layer (3c2): Layer (3c2) is obtained by crosslinking the following composition, expressed as relative parts by dry weight: - Organopolysiloxanes with vinyl reactive functional groups (-CH=CH2): 100 parts, - Another organopolysiloxane with a thiol reactive functional group (SH): 8 parts, and - Free radical initiator: 15 parts.

[0233] The above-mentioned dry composition is mixed with a solvent to obtain a dry extract with a mass content of about 10% to 20%.

[0234] After applying layer (3c2), the entire assembly is placed in an oven at 100°C for 20 minutes to dry, then crosslinked with layer (3c2), and then baked in an oven at 300°C for 20 minutes to complete the baking process. Finally, the disc is cooled.

[0235] Examples 1 to 6 correspond to the following arrangement of layers (3): Table 10 test Methods for evaluating stampability: The stamping test, known as the Swift test, is performed using a Zwick BPU 400 stamping press.

[0236] Experimental conditions: - Cut the disk into pieces with a diameter of 64 mm. - Punch 33 mm (limit drawing ratio = 1.9). - Stamping die: 40 mm.

[0237] The stampability of a coating on a given substrate is represented by binary notation: - OK: Good stampability = good adhesion of the coating to the substrate after stamping deformation - Not OK: Poor stampability = Poor adhesion of the coating to the substrate after stamping deformation.

[0238] Stamping deformation is performed in two ways; the evaluation of adhesion differs depending on the deformation method. These methods are considered to provide comparable results.

[0239] Laboratory size method: The coated aluminum substrate is deformed on a small area (requiring a disc of approximately 10 cm in diameter) using a press according to the "Erikson cup" or "Gorde cup" method: "Eriksen Cup": The press uses a conical, round-headed punch to deform the surface to a depth of approximately 1 to 2 cm, with the coating on the outer side. This deformation method also subjectes the coating to tension. If, after deformation, the coating appears highly cracked or peels / detaches from the substrate, its resistance to stamping deformation is poor. To magnify the difference, a grid can be pre-marked on the area where the punch is applied (according to ISO 2409 standard), and then observed for significant square peeling (regardless of whether tape is applied).

[0240] "Gorde Cup": The press deforms the substrate with a cylindrical punch (rounded edge), with the coating on the inside. This better simulates the deformation of the substrate when it is stamped into a stew pot, even though 0% stretching was applied to the skirt (cylindrical edge) during testing. A poor result is indicated when any delamination, wrinkling, or other coating defects are observed after deformation.

[0241] Anti-stick properties: Evaluation method for anti-stick coating performance: Egg performance test The evaluation method for the performance of the anti-stick coating is based on the egg test described in paragraph 3.3.2 of AFNOR NF D 21-511 standard, and is carried out as follows: Clean the sample and then wipe away any remaining water from the surface.

[0242] After the inner surface of the container body dries, apply oil.

[0243] Heat the oiled cooking container on a gas stove to a temperature between 140 and 170°C.

[0244] Crack a 60 / 65-inch egg into the center of a hot cooking container and allow it to set (6 to 9 minutes). Remove the egg from the cooking container with a spatula, clean the coating with a damp vegetable sponge, and evaluate the non-stick properties of the cooking container by doing so. Record the results: Rating 100: The egg was completely removed with a plastic spatula; Rating 75: The egg was not completely removed, but the coating was easy to clean with a damp sponge; Rating 25: The egg was not completely removed, and the coating cannot be cleaned with a wet sponge; Rating 0: The egg was not removed and the coating could not be cleaned with a wet sponge.

[0245] result The test results for stampability and non-stick properties are summarized below: Table 11 The coating according to the invention comprises layers (3a) and (3c), such that the coating has satisfactory resistance (adhesion), good corrosion resistance and good non-stick properties in the initial state and after three aging cycles in boiling water and oil.

Claims

1. A coated heating element (1) for household articles, comprising a metal substrate (2) coated on at least one side (2a) by a coating (3), the coating being free of fluorocarbon resin and comprising at least the following layers in the following order from the metal substrate (2): (3a) A base coating comprising polyethersulfone (PES). (3b) One or more intermediate layers (3b) comprising polyethersulfone (PES) or a mixture of polyethersulfone (PES) and one or more silicone resins; (3c) A topcoat, which consists of the following: - An elastomeric silicone derived from at least one organopolysiloxane having a vinyl reactive functional group (-CH=CH2) and at least another organopolysiloxane having a silane-hydrogen reactive functional group (Si-H) or a thiol reactive functional group (SH), and optionally: - One or more thermoplastic polymers, and / or - One or more additives, and / or - One or more colorants, The layer (3a) is different from at least one of the layers (3b).

2. The coated heating element (1) according to claim 1, characterized in that, The PES content in the base layer (3a) is lower than the PES content in one or more layers (3b).

3. The coated heating element (1) according to claim 2, characterized in that, The PES content increases from the base coat (3a) to the last layer (3b).

4. The coated heating element (1) according to any one of the preceding claims, characterized in that, The PES content in the primer (3a) is 50% to less than 75% of the weight of the primer (3a).

5. The coated heating element (1) according to any one of the preceding claims, characterized in that, The PES content in one or more intermediate layers (3b) is 75% to 98% of the weight of one or more of the layers.

6. The coated heating element (1) according to any one of the preceding claims, characterized in that, The thickness of each layer in the coatings (3a) and (3b) is 5 µm to 15 µm.

7. The coated heating element (1) according to any one of the preceding claims, characterized in that, The organopolysiloxane with reactive functional groups in the layer (3c) is silicone oil.

8. The coated heating element (1) according to any one of the preceding claims, characterized in that, The thickness of the topcoat (3c) is 0.1 µm to 10 µm, preferably 0.5 µm to 5 µm, and more preferably 1 µm to 2 µm.

9. The coated heating element (1) according to any one of the preceding claims, characterized in that, The elastomeric silicone of the layer (3c) is obtained from at least one organopolysiloxane with a vinyl reactive functional group (-CH=CH2) and at least another organopolysiloxane with a silane-hydrogen reactive functional group (Si-H), and is obtained in the presence of a metal catalyst.

10. The coated heating element (1) according to any one of claims 1 to 8, characterized in that, The elastomeric silicone of the layer (3c) is obtained from at least one organopolysiloxane with a vinyl reactive functional group (-CH=CH2) and at least another organopolysiloxane with a thiol reactive functional group (SH), and is obtained in the presence of a free radical initiator.

11. A method for manufacturing a household article, said household article comprising a coated heating element (1) coated with a coating (3) according to any one of the preceding claims. Its characteristics include the following steps: a) The step of providing a metal substrate (2) is in the form of a generally flat metal substrate having two opposite surfaces, or in the form of a convex or concave support (2) defining a concave inner surface (21) and a convex outer surface (22). b) Where applicable, when a metal substrate in the form of a generally flat metal substrate is provided in step (a), the step of shaping the substrate to give it the shape of a convex or concave support (2), the convex or concave support defining a concave inner surface (21) and a convex outer surface (22), the step (b) being performed either before step (a), or before step (d) of preparing layers (3a) and (3b) of coating (3), or after step (f) of calcination and before step (g) of preparing the topcoat, or after step (g); c) Optionally, a step of treating at least one surface (2a) of the metal substrate (2) to obtain a treated surface (2a) to promote the adhesion of the base coating (3a) to the support (2); d) The steps of applying coating (3) to layers (3a) and (3b); e) Optionally, a drying step is performed between 50°C and 150°C after applying each layer (3a) (3b); f) Optionally, the element obtained in step d) or e) is calcined at a temperature between 250°C and 420°C; g) Applying a surface coating (3c) to the element obtained in step d), e), or f); h) Optionally, the element obtained in step g) is calcined at a temperature between 250°C and 420°C.

12. The method according to claim 11, characterized in that, In step g), the topcoat (3c) is applied by electrostatic spraying, spraying, screen printing, spray gun, doctor blade, coating roller, brush, roller coating or digital printing, preferably by spraying.

13. The method according to claim 11 or 12, characterized in that, The method includes step g', which crosslinks the surface coating (3c), performed after or simultaneously with step g).

14. The method according to claim 13, characterized in that, The crosslinking of the topcoat (3c) was carried out at 300°C for 10 minutes.

15. A household article comprising a coated heating element according to any one of claims 1 to 10 or a coated heating element obtainable by the method according to any one of claims 11 to 14.

16. The household article according to claim 15, characterized in that, The household item is a cooking appliance or electric cooking device, and the layer (3c) forms a cooking surface (5).

17. The household article according to claim 16, characterized in that, The colorant of the layer (3c) is a flake pigment.

18. The household article according to claim 15, characterized in that, The household item is a cooking appliance or electric cooking device, and the layer (3c) is in contact with a heat source.

19. The household article according to any one of claims 15 to 18, characterized in that, The household items are cooking appliances (100) selected from: stew pots, frying pans, small pots or long-handled skillets for cheese fondue or cheese gratin, double-handled saucepans, frying pans, woks, crepe pans, grills, flat baking trays, deep pots, casseroles, cookware liners or bread machine liners, cooking molds, pastry molds and baking trays, grill racks and grill baskets, and cooking bowls.

20. The household article according to any one of claims 15 to 18, characterized in that, The household items are electric cooking appliances (200), selected from: electric crepe makers, electric cheese grills, electric cheese fondues, electric grills, electric flat griddles, electric cookers, bread makers, pressure cookers, waffle makers, rice cookers, and jam makers.

21. The household article according to claim 15, characterized in that, The household item in question is a small heating household appliance.

22. The household article according to claim 21, characterized in that, The household item is an iron, and the coated heating element is the soleplate of the iron; or a hair care product, and the coated heating element is one of the heating plates of the product.

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