Non-fluorinated thermoplastic polymer / elastomeric silicone coating

Abstract

The invention relates to a coated heating element (1) for a household appliance, comprising a metal substrate (2) coated on at least one surface (2a) with a coating (3) that does not comprise a fluorocarbon resin, and having at least the following layers in the stated order proceeding from the metal substrate (2): (3a) a primer layer comprising one or more aromatic or heterocyclic thermoplastic polymers; (3b) one or more intermediate layer(s) comprising one or more aromatic or heterocyclic thermoplastic polymers or a mixture of one or more aromatic or heterocyclic thermoplastic polymers and one or more silicone resins; (3c) a finishing layer consisting of: - an elastomeric silicone obtained from at least one organopolysiloxane bearing reactive vinyl functions (-CH=CH2) and at least one other organopolysiloxane bearing reactive silyl hydride functions (Si-H) or reactive thiol functions (S-H); and optionally: - one or more thermoplastic polymer(s), and / or - one or more additive(s), and / or - one or more colouring agent(s), wherein the layer (3a) is different from at least one of the layers (3b).

Description

[0001] Non-fluorinated thermoplastic polymer / silicone elastomer coating

[0002] The invention applies in the field of non-stick coatings for household items, which are heated or can be heated, in particular for kitchen items and electrical cooking appliances.

[0003] PTFE (polytetrafluoroethylene) coated cookware is popular on the market because it allows for cooking food with little or no added fat and is easy to maintain. However, an inherent weakness of these coatings is their low mechanical strength, especially when hot. Another inherent weakness of PTFE is its ductility, which makes the coatings easy to mark, scratch, and wear with metal utensils (spatulas, forks, spoons, blender sticks, etc.).

[0004] To remedy this, numerous technical solutions have been proposed which consist of reinforcing the coating with hard fillers or by interposing hard sub-layers of an inorganic or organic type.

[0005] In the case of primers reinforced with hard organic or inorganic fillers, significant improvements in abrasion resistance are indeed observed, but impacts to metal are also observed when cooking foods such as pork chops or when using metal spatulas.

[0006] In the case of hard inorganic bases such as those made from enamel or metal oxides, abrasion resistance is further improved and the impact problem is limited without being eliminated.

[0007] Organic polymer undercoats are also known. These undercoats can effectively reduce the appearance of scratches considerably or even eliminate them. This strategy is therefore very interesting. The polymers used are very often thermoplastic polymers with high thermal resistance and a high melting point, such as polyaryletherketone, particularly oxy-1,4-phenylenephenylene-oxy-1,4-phenylene-carbonyl-1,4-phenylene or PEEK, or phenylene sulfides.

[0008] PEEK polymer is of interest in cookware because it has a high melting point (343°C) and excellent thermal stability under operating conditions of 260°C. The following coating techniques can be used to obtain an undercoat from this type of polymer: spray coating, roller coating, curtain coating, pad printing, screen printing, thermal projection, electrostatic spraying, inkjet.

[0009] Pure silicone resins are described as 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.

[0010] Conversely, silicone-polyester resins are widely used in molding because they are non-stick while adhering to the substrate and compatible with stamping processes. However, they degrade at temperatures above 230°C. Indeed, the operating temperature range for cookware 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 not compatible with the operating temperatures in the field of cookware.

[0011] The present invention deals with the technical problem of improving the anti-adhesiveness of a coating with high thermo-mechanical properties.

[0012] The present invention also addresses the technical problem of alternative solutions to PTFE-type fluorinated resin-based coatings.

[0013] The present invention provides an alternative to predominantly PTFE-based coatings with a view to obtaining good resistance to mechanical wear of the coatings, in particular by kitchen utensils for culinary articles and thus improving the durability of their mechanical resistance, in particular when hot and / or their cleanability, in order to extend the life of the article.

[0014] DEFINITIONS

[0015] The term "layer" is understood to mean, within the meaning of the present invention, a continuous or discontinuous layer. A continuous layer (or also called a monolithic layer) is a single whole forming a total flat area completely covering the surface on which it is applied. A discontinuous layer (or non-monolithic layer) may comprise several parts which are not therefore a single whole. The term "base layer", "primer layer", "bonding layer" or "bonding primer" means all the layers from the first layer applied directly to the support (it is preferable that this layer adheres well to the support and provides all its mechanical properties to the coating: hardness, scratch resistance) to the last layer before the first intermediate or decorative layer or the finishing layer if the coating does not include an intermediate layer. The first layer of the coating is a primer layer.

[0016] The term "intermediate layer" means 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.

[0017] The term "finish coat" or "finish" means one or more continuous surface layers applied after the intermediate layer(s) if the coating comprises one or more intermediate layer(s) or after the primary layer(s). The last layer of the coating is a finishing layer. Usually, at least the last finishing layer, or even all finishing layers, is / are transparent to allow visibility of the underlying layers, in particular when the underlying layers are decorative layers. The finishing layer(s) protect the underlying layers from mechanical attack and give the coating its non-stick properties. Preferably, in the case of a cookware or electrical cooking appliance, the last finishing layer is intended to be in contact with food.

[0018] The term "decor" or "decorative layer" means one or more continuous or discontinuous layers comprising a pigment composition. The decor may be in the form of one or more patterns, one or more colors. A decor is clearly visible to the user with the naked eye and at a normal distance from the household item.

[0019] Overlapping layers are defined as partially or completely overlapping layers. These layers may be in the form of partially overlapping patterns, for example concentric discs. Adjacent layers are defined as non-overlapping layers. These layers may be in the form of identical or different non-overlapping patterns, preferably uniformly distributed.

[0020] The term "temperature reference pigment composition" means a composition comprising a pigment which, at a given temperature, indicates to the user that the optimum operating temperature has been reached. This indication is made by comparing the colours of the thermochromic pigment composition and the temperature reference pigment composition. Either the optimum operating temperature is reached when the colours are identical, or the optimum operating temperature is reached when the colours are visually very different.

[0021] The “temperature reference pigment composition” may include a pigment that has:

[0022] - the same color as the thermochromic pigment composition, at the optimal operating temperature,

[0023] * either because this pigment has the same color at room temperature as the thermochromic pigment composition at the optimum temperature of use, and does not change color with temperature,

[0024] * either because this pigment has a different color at room temperature from that of the thermochromic pigment composition which evolves to the same color as the thermochromic pigment composition at the optimal use temperature,

[0025] - a color very different from that of the thermochromic pigment composition at the optimum temperature of use, whether or not this pigment changes color with the change in temperature.

[0026] The optimum operating temperature can be achieved when the color of the temperature reference pigment composition corresponds to a color indicated in the user guide for the household article comprising the coating of the invention or to a color indicated on a color scale provided to the user with said article.

[0027] The temperature reference pigment composition is thermochromic or thermostable. The temperature reference pigment composition may be, for example, a cooking temperature reference pigment composition or an overheating risk indication pigment composition.

[0028] The expression "thermochromic semiconductor" is understood to mean, within the meaning of the present invention, a mineral or organic compound which exhibits a reversible change in color upon increasing temperature. The progressive and reversible thermochromic nature of these semiconductor compounds is linked to the reduction in the width of the forbidden band of the semiconductor due to the expansion of the material. Indeed, the periodicity of the network of anions and cations leads to the gathering of energy levels into energy bands. The filled energy band with the highest energy is called the valence band and the empty energy band with the lowest energy is called the conduction band. Between these two bands, there is a forbidden band called the gap.The color of a semiconductor material can come 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 photonic 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 the present invention, the term "thermochromic pigment or pigment composition" means a pigment or pigment composition which changes color depending on the temperature in a given temperature range, this change being reversible. This color change is visible to the user with the naked eye and at a conventional operating distance.

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

[0032] L, ai* and b characterizing the L*a*b values ​​of said compound at room temperature L2*, a2* and b2* characterizing the L*a*b values ​​of said compound at 200°C.

[0033] By "the colors are identical" we mean indistinguishable by the user with the naked eye and at a normal viewing distance.

[0034] The expression "cooking article" is understood to mean, within the meaning of the present invention, an object intended for cooking and being heated by an external heating system such as frying pans, saucepans, sauté pans, woks, barbecue grills. A cooking article is capable of transmitting the heat energy provided by this external heating system to a material or food in contact with said article.

[0035] The expression "electric cooking appliance" is understood to mean, within the meaning of the present invention, a heating object having its own heating system, such as an electric crepe maker, an electric raclette appliance, an electric fondue appliance, an electric grill, an electric griddle, an electric cooker, a bread maker, or an electric pressure cooking appliance.

[0036] The term "coating" means all the layers adhering to the metal substrate and covering this substrate. The coating according to the invention obtained is advantageously solid, "solid" means the characteristic of a cohesive material insoluble in water, in common solvents, in food components such as aqueous or fatty mixtures, even if the material may have great hardness or great flexibility such as an elastomer.

[0037] In the present invention, the % by weight are expressed in dry weight, i.e. without solvent.

[0038] SUMMARY OF THE INVENTION

[0039] A first subject of the invention relates to a coated heating element (1) for a household article, comprising a metal substrate (2) coated on at least one face (2a) with a coating (3) free of fluorocarbon resin and comprising at least the following layers and in this order starting from the metal substrate (2):

[0040] (3a) a primer layer comprising one or more aromatic or heterocyclic thermoplastic polymers;

[0041] (3b) one or more intermediate layer(s) comprising one or more aromatic or heterocyclic thermoplastic polymers or a mixture of one or more aromatic or heterocyclic thermoplastic polymers and one or more silicone resins;

[0042] (3c) a finishing layer consisting of:

[0043] - an elastomer silicone obtained from at least one organopolysiloxane carrying reactive vinyl functions (-CH=CH2), and at least one other organopolysiloxane carrying reactive silyl hydride functions (Si-H) or reactive thiol functions (SH), and optionally:

[0044] - one or more thermoplastic polymers, and / or

[0045] - one or more additive(s), and / or

[0046] - one or more coloring agents; the layer (3a) being different from at least one of the layers (3b).

[0047] Another subject of the invention relates to a method of manufacturing a household article comprising a heating element coated (1) with a coating (3) according to the invention characterized by the following steps: a) a step of providing a metal substrate (2) in the form of a substantially flat metal substrate comprising two opposite faces or a support (2) of convex or hollow shape defining a concave inner face (21) and a convex outer face (22);b) where appropriate, when a metal substrate in the form of a substantially flat metal substrate is provided during step (a), a step of shaping said substrate to give it the shape of a support (2) of convex or hollow shape defining a concave inner face (21) and a convex outer face (22), said step (b) being carried out either before step (a), or before step (d) of producing the layers (3a) and (3b) of the coating (3), or after step (f) of baking and before step (g) of producing the finishing layer or after step (g); c) optionally, a step of treating at least one face (2a) of the metal 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 the layers (3a) (3b) of the coating (3); e) optionally a drying step between 50°C and 150°C after application of each of the layers (3a) (3b);f) optionally a step of baking the element obtained in step d) at a temperature between 250°C and 420°C; g) a step of applying the finishing layer (3c) to the element obtained in step d), e) or f); h) optionally a step of baking the element obtained in step g) at a temperature between 250°C and 420°C.;

[0048] Another subject 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 method of the invention.

[0049] FIGURES

[0050] [Fig. U • diagram of cooking element according to the invention with layer (3b) is continuous and covers the entire layer (3a)

[0051] [Fis.2]: diagram of a cooking element according to the invention with the layer (3b) not covering the entire layer (3a) and forming a decoration

[0052] [Fig.3]: diagram of a cooking element according to the invention with layer (3b) consisting of two decorations (i) and (j)

[0053] [Fig.4] 'Pattern distribution diagram. 4A = adjacent non-overlapping patterns. 4B = partially overlapping patterns. 4C = overlapping patterns.

[0054] [Fis.5] ' diagram of a culinary article according to the invention

[0055] [Fis.6] ' diagram of an electrical cooking appliance according to the invention

[0056] DETAILED DESCRIPTION

[0057] A first subject of the invention relates to a coated heating element (1) for a household article, comprising a metal substrate (2) coated on at least one face (2a) with a coating (3) free of fluorocarbon resin and comprising at least the following layers and in this order starting from the metal substrate (2):

[0058] (3a) a primer layer comprising one or more aromatic or heterocyclic thermoplastic polymers;

[0059] (3b) one or more intermediate layer(s) comprising one or more aromatic or heterocyclic thermoplastic polymers or a mixture of one or more aromatic or heterocyclic thermoplastic polymers and one or more silicone resins;

[0060] (3c) a finishing layer consisting of: a silicone elastomer obtained from at least one organopolysiloxane carrying reactive vinyl functions (-CH=CH2), and at least one other organopolysiloxane carrying reactive silyl hydride functions (Si-H) or reactive thiol functions (SH), and optionally: one or more thermoplastic polymers, and / or one or more additive(s), and / or one or more coloring agents; the layer (3a) being different from at least one of the layers (3b).

[0061] Advantageously, the layers (3a), (3b) and (3c) form a coating (3) which coats the metal substrate (2). This coating (3) has non-stick properties and forms a non-stick coating, which non-stickness is particularly conferred by the layer (3c).

[0062] Advantageously, the layer (3a) is in contact by one of its faces with the metal substrate (2) by its face (2a).

[0063] When the household item is a kitchen item or an electrical cooking appliance, the coated face (2a) of the metal substrate forms a cooking face. In other words, the coating (3) according to the invention is then intended to be in contact with food. Advantageously, the finishing layer (3c) is then in contact by one of its faces with food and thus forms a cooking surface (5).

[0064] The coating (3) according to the invention does not comprise fluorocarbon resin, also called 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.

[0065] Advantageously, the thickness of the layer(s) (3a) and (3b) is between 1 pm and 100 pm, preferably between 2 pm and 30 pm, particularly preferably between 3 pm and 10 pm. Advantageously, the thickness of the layer (3c) is between 0.1 pm and 10 pm, preferably between 0.5 pm and 5 pm, even more preferably between 1 and 2 pm.

[0066] Advantageously, the content of aromatic or heterocyclic thermoplastic polymers in the primer layer (3a) is lower than the content of aromatic or heterocyclic thermoplastic polymers in the layer(s) (3b). Preferably, according to this embodiment, the content of aromatic or heterocyclic thermoplastic polymers increases from the primer layer (3a) to the last layer (3b).

[0067] LAYERS (3a) and (3b)

[0068] The primer layer (3a) comprises one or more aromatic or heterocyclic thermoplastic polymers.

[0069] The intermediate layer(s) (3b) comprises one or more aromatic or heterocyclic thermoplastic polymers or a mixture of one or more aromatic or heterocyclic thermoplastic polymers and one or more silicone resins.

[0070] Advantageously, the primer layer(s) (3a) or the intermediate layer(s) (3b) comprises from 20% to 100% by weight of one or more aromatic or heterocyclic thermoplastic polymers relative to the weight of said layer.

[0071] Advantageously, the content of aromatic or heterocyclic thermoplastic polymers in the primer layer (3a) represents from 50 to 75% by weight of the primer layer (3a).

[0072] Advantageously, the content of aromatic or heterocyclic thermoplastic polymers in the intermediate layer(s) (3b) represents from 75 to 100% by weight of said layer(s).

[0073] At least one intermediate layer (3b) is present in the coating (3) according to the invention. Advantageously, the at least one intermediate layer (3b) is different from the primer layer (3a). More preferably, in this case, all the intermediate layers (3b) are different from the primer layer (3a). Advantageously, the primer layer (3a) is different from all the intermediate layers (3b). Advantageously, the primer layer(s) (3a) or the intermediate layer(s) (3b) comprises / comprise one or more fillers. According to this embodiment, the primer layer(s) (3a) or the intermediate layer(s) (3b) comprises / comprise 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.

[0074] According to one embodiment, the primer layer(s) (3a) or the intermediate layer(s) (3b) comprises 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.

[0075] According to one embodiment, the primer layer(s) (3a) or the intermediate layer(s) (3b) comprises / comprise one or more coloring agent(s). Advantageously, the primer layer(s) (3a) or the intermediate layer(s) (3b) comprises / comprise less than 30%, preferably less than 20%, by weight of one or more coloring agent(s) of the total weight of said layer.

[0076] Advantageously, the primer layer(s) (3a) or the intermediate layer(s) (3b) further comprises / comprise water and / or one or more solvents, preferably unlabeled, for example propionamide, N-formylmorpholine (NFM), N-Methyl Imidazole (NMI), N-ButylPyrrolidone (NBP), dimethyl sulfoxide (DMSO), or alcoholics, for example Propylene Glycol (PPG), Diethylene glycol, di propylene glycol butyl ether (DPNB).

[0077] Advantageously, the primer layer(s) (3a) or the intermediate layer(s) (3b) comprises one or more surfactants.

[0078] Advantageously, the primer layer(s) (3a) or the intermediate layer(s) (3b) further comprises one or more anti-foaming agents.

[0079] According to one embodiment, the primer layer (3a) is made up of one or more aromatic or heterocyclic thermoplastic polymers and optionally: one or more additives, and / or one or more coloring agent(s), and / or one or more filler(s). According to one embodiment, the intermediate layer(s) (3b) is / are made up of one or more aromatic or heterocyclic thermoplastic polymers or a mixture of one or more aromatic or heterocyclic thermoplastic polymers and one or more silicone resins and optionally: one or more additives, and / or one or more coloring agent(s), and / or one or more filler(s).

[0080] LAYER (3c)

[0081] The finishing layer (3c) consists of: an elastomer silicone obtained from at least one organopolysiloxane carrying reactive vinyl functions (-CH=CH2) and at least one other organopolysiloxane carrying reactive silyl hydride functions (Si-H) or reactive thiol functions (SH), and optionally: one or more thermoplastic polymers, and / or one or more additive(s), and / or one or more coloring agents.

[0082] The elastomeric silicone of layer (3c) forms a network which can be made up of a combination of 4 simple organosiloxane units named M, D, T and Q depending on the degree of substitution by oxygen of the silicon atom, as described in the following table, where R is an organic substituent described below.

[0083] Table 1 The precursors of the elastomer 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, in particular phenyl, different natures of R being able to be present on the same macromolecule.

[0084] Organopolysiloxanes can be either linear or sparsely branched (majority of D groups). Linear or sparsely branched organopolysiloxanes are generally liquid, more or less viscous at room temperature, and are called silicone oils.

[0085] The organopolysiloxanes carrying reactive functions of layer (3c) are precursors which react by a crosslinking which is a polyaddition. This crosslinking is carried out by reaction between the reactive vinyl functions (-CH=CH2) present on one of the organopolysiloxanes and the reactive silyl hydride functions (Si-H) or the reactive thiol functions (SH) present on the other organopolysiloxane mixed with the first.

[0086] This crosslinking can be done by thermal activation, activation by UV irradiation or chemical activation. Preferably, this crosslinking is done in the presence of a catalyst or a radical initiator.

[0087] According to one embodiment, when the crosslinking is carried out 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, the reaction is preferably carried out in the presence of a metal catalyst, for example platinum or a suitable platinum-based catalyst such as the Karstedt catalyst or the Ashbys catalyst.

[0088] According to one embodiment, when the crosslinking is carried out by reaction between the vinyl reactive functions (-CH=CH2) present on one of the organopolysiloxanes and the thiol reactive functions (SH) present on the other organopolysiloxane mixed with the first, the reaction is preferably carried out in the presence of a radical initiator. According to one embodiment, it may be a thermally activated radical initiator such as, for example, 2,2'-Azobis(2-methylpropionamidine) dihydrochloride (or V50). According to one embodiment, it may be a radical initiator activated by UV irradiation such as, for example, Irgacure®651 (2,2-Dimethoxy-2-phenylacetophenone). Advantageously, the organopolysiloxanes carrying reactive functions of layer (3c) are silicone oils.

[0089] Reactive functions are present on each organopolysiloxane in the number of at least one and can be present in the number of 2, 3, or more ... as much as the molecular structure allows. Silicone oils containing at least one reactive function are called "reactive oils". The reactive functions can be found either at the end of the macromolecular chain (termination), or distributed over the chain.

[0090] THERMOPLASTIC POLYMERS

[0091] Advantageously, the thermoplastic polymer(s) is / are chosen from the group consisting of aromatic thermoplastic polymer(s) such as polyaryletherketone(s) (PAEK), poly(arylethersulfones) (PAES), poly(arylene sulfides) (PAS) or poly(phenylene oxide) (PPO), liquid crystal polymers, heterocyclic thermoplastic polymers and mixtures thereof.

[0092] PAEK

[0093] 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.

[0094] Other aromatic thermoplastic polymers

[0095] As aromatic thermoplastic polymer(s), examples suitable according to the invention are poly(phenylene oxide) (PPO), poly(arylethersulfone) polymer (PAES), and in particular polyethersulfone (PES), polyphenylene ether sulfone (PPSU), poly(arylene sulfides) (PAS) and in particular polyphenylene sulfide (PPS), liquid crystal polymers and mixtures thereof.

[0096] Heterocyclic thermoplastic polymers

[0097] Examples of heterocyclic thermoplastic polymers suitable according to the invention are polyetherimides (PEI), polyimides (PI), polyamideimides (PAI) and polybenzymidazole (PBI), or mixtures thereof. Advantageously, the thermoplastic polymer(s) is / are chosen 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), 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 mixtures thereof.

[0098] Alternatively, the PAEK is implemented in the form of a suspension and the PAEK particles in the PAEK suspensions have a particle size with a d50 of about 10 pm to 15 pm.

[0099] Advantageously, the nature of the thermoplastic polymer(s) in layers (3a), (3b) and (3c) may be identical or different.

[0100] Advantageously, the layer (3b) comprises one or more thermoplastic polymer(s), preferably in a proportion by weight of said layer of less than 50%, preferably 40%.

[0101] Advantageously, the layer (3a) comprises one or more thermoplastic polymer(s), preferably in a proportion by weight of said layer of less than 30%, preferably 20%.

[0102] Advantageously, the layer (3b) comprises one or more thermoplastic polymer(s), preferably in a proportion by weight of said layer of less than 50%, preferably 40%.

[0103] Advantageously, the layer (3c) comprises one or more thermoplastic polymer(s), preferably in a proportion by weight of said layer of less than 15%, preferably 10%.

[0104] According to one embodiment, the layer (3a) and the layer (3b) comprise one or more thermoplastic polymer(s), the proportion of thermoplastic polymer(s) in the layer (3b) being preferably greater than the proportion of thermoplastic polymer(s) in the layer (3a). FILLERS

[0105] The fillers within the meaning of the invention provide mechanical reinforcement and can also provide hydrophobic properties, while improving the mechanical resistance and thermal conductivity of the coating.

[0106] Fillers are not only intended to add color to the coating, but can also contribute to it.

[0107] Advantageously, the filler(s) is / are chosen from the group consisting of ceramic fillers (SiO?, etc.) and / or mineral and / or metallic fillers (AI2O3, TiO?, etc.) and / or silicas and / or diamond particles.

[0108] Preferably, the filler(s) is / are chosen from the group consisting of metal oxides, metal carbides, metal oxynitrides, metal nitrides, and mixtures thereof.

[0109] Advantageously, said metal is a transition metal, such as at least one of the elements chosen from B, Ni, Ti, Zr or Hf.

[0110] More preferably, the charge(s) is / are chosen from the group consisting of:

[0111] - fillers for reinforcement: organic or inorganic hard fillers; the inorganic hard fillers 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;

[0112] - other fillers for reinforcement chosen from metal oxides: silica, micas, lamellar fillers, clays such as montmorillonite, sepiolite, gypsite, kaolinite and laponite, zinc dioxide, quartz, and zirconium phosphate, alumina, zirconia, zinc oxide, copper oxide, iron oxide;

[0113] - fillers chosen from reinforcing fibers: glass fiber, carbon fiber, or aramid fiber;

[0114] - conductive fillers comprising a transition metal carbide and / or a transition metal nitride: characterized in that the transition metal is at least one of the elements chosen from B, Ni, Ti, Zr or Hf; for example: cubic boron nitride, diamond particles, metallic particles; - lamellar fillers capable of conferring lubricating properties, such as for example clays, graphene or graphite.

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

[0116] - reinforcing fillers: silica or carbonates with filler rates of at least 10-15% / wt and up to 60% / wt,

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

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

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

[0120] More 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 primer layer(s) (3a) or the intermediate layer(s) (3b) are inorganic hard fillers, preferably metal oxides, carbides, nitrides, preferably alumina, silicon carbides or fumed silica.

[0122] Some 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] The addition of this type of filler improves the culinary rendering with better diffusion of heat from the metal 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, when it comprises them, is between 0.5 and 30% by dry weight relative to the total weight of said layer after cooking, preferably between 5 and 20%. Advantageously, the proportion of fillers in the layer (3a) is greater than 20% by weight, preferably greater than 30% by weight, relative to the total weight of said layer.

[0126] Advantageously, the proportion of charges in layers (3a) and (3b) may be identical or different.

[0127] Advantageously, the nature of the charges in layers (3a) and (3b) may be identical or different.

[0128] ADDITIVES

[0129] Advantageously, said additives are chosen from the group consisting of anti-foam agents, dispersing agents, wetting agents, thickeners, pH adjusters, reactive silicone oils.

[0130] Said anti-foaming agent(s) are preferably chosen from the group consisting of mineral oils, diols, hydrocarbons, glycerides, oxirane, emulsified fatty acids.

[0131] The surfactant(s) is (are) preferably chosen from the group consisting of glycol ether, ethoxylated alcohol excluding alkyl phenol ethoxylates (APE), gemini surfactants.

[0132] The dispersing agent(s) is (are) preferably chosen from the group consisting of anionic dispersants such as fatty acid derivatives.

[0133] The said thickener(s) is (are) preferably chosen from the group consisting of acrylic-based or polyurethane-based copolymer, cellulose, fumed silica.

[0134] The said pH adjuster(s) is (are) preferably chosen from the group consisting of Bronsted bases: ammonia, amines (triethylamine, triethanolamine, etc.), hydroxides (soda, potash, etc.), carbonates.

[0135] Advantageously, the proportion of additives in the layer (3a) is less than 1% by weight relative to the total weight of said layer. Advantageously, the proportion of additives in the layer (3c) is less than 20% by weight relative to the total weight of said layer.

[0136] COLOURING AGENTS

[0137] Advantageously, the coloring agent(s) is / are chosen from the group consisting of thermochromic pigments, thermostable pigments, glitter, preferably hologram glitter, and mixtures thereof.

[0138] Advantageously, the proportion of coloring agents in layers (3a), (3b) and (3c) is between 0.5 and 50% by dry weight relative to the total weight of said layer after cooking.

[0139] 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.

[0140] 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.

[0141] Advantageously, the proportion of coloring agents in layers (3a), (3b) and (3c) may be identical or different.

[0142] Advantageously, the nature of the coloring agents in layers (3a), (3b) and (3c) may be identical or different.

[0143] Advantageously, layer (3c) is transparent. In this case, if it includes coloring agents, these coloring agents are glitter.

[0144] Thermochromic pigments

[0145] Preferably, the thermochromic pigment(s) is / are selected from the group consisting of Bi2O3, Fe2O3, V2O5, WO3, CeO2, ln2O3, Yi,84Cao,i6Tii,84Vo,i60i,84, Agi, (Bii- X HAS X ) (Vi- y My)04 with x equal to 0 or x is from 0.001 to 0.999, y equal to 0 or y is from 0.001 to 0.999, A and M are selected from the group consisting of nitrogen, phosphorus, an alkali metal, a n-alkali metal, a transition metal, a poor metal, a metalloid or a lanthanide,

[0146] A and M are different from each other.

[0147] Knowing that A and M are different from each other, when:

[0148] - A is an alkali metal, it can be chosen from Li, Na, K, Rb, Cs,

[0149] - M is an alkali metal, it can be chosen from Li, Na, K, Rb, Cs,

[0150] - A is a noterous alkali metal, it can be chosen from Be, Mg, Ca, Sr, Ba,

[0151] - M is a noterous alkali metal, it can be chosen from Be, Mg, Ca, Sr, Ba,

[0152] - 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,

[0153] - 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,

[0154] - A is a poor metal, it can be chosen from Al, Zn, Ga, In, Sn,

[0155] - M is a poor metal, it can be chosen from Al, Zn, Ga, In, Sn,

[0156] - A is a metalloid, it can be chosen from B, Si, Ge, Sb,

[0157] - M is a metalloid, it can be chosen from B, Si, Ge, Sb,

[0158] - A is a lanthanide, it can be chosen from La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu,

[0159] - M is a lanthanide, it can be chosen from La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu.

[0160] Preferably, A and M different from each other are B and / or Mg.

[0161] Preferably, the pigment (Bii. x HAS x )(Vi.yMy)O4 exhibits a monoclinic scheelite crystallographic form at room temperature.

[0162] Preferably, x and y are 0, i.e. the pigment (Bii. x HAS x )(Vi. y M y )O4 is Bismuth Vanadate (B1VO4). Advantageously, a B1VO4 with a monoclinic scheelite crystallographic structure at room temperature is used.

[0163] Bismuth Vanadate is a yellow inorganic compound with the formula B1VO4, widely used for its color properties and lack of toxicity. Registered in the Colour Index International database as QI Pigment Yellow 184, it is marketed by Heubach (Vanadur®), BASF (Sicopal®), FERRO (Lysopac) and Bruchsaler Farbenfabrik (Brufasol®).

[0164] Thermostable pigments

[0165] Preferably, the thermostable pigment(s) is / are chosen from the group consisting of:

[0166] - Yellow titanium rutile pigment,

[0167] - Yellow pigment derived from bismuth, for example selected from stabilized bismuth vanadates (Py^)

[0168] - Red pigment, for example selected from perylene red (for example PR149, PR178 and PR224), iron oxide,

[0169] - Orange pigment of bismuth oxyhalides type (POss),

[0170] - Bismuth vanadate orange pigment (POSÔ)

[0171] - Zinc tin titanium orange pigment (POs?)

[0172] - Cerium sulfide orange pigment (PO75; PO?s)

[0173] - Orange-yellow pigment of the antimony titanium chrome rutile type (PBr?4)

[0174] - Orange-yellow pigment of the rutile type of tin and zinc (Pyz-iô)

[0175] - Orange-yellow pigment of niobium oxide tin zinc sulfide (Py???)

[0176] - Orange-yellow pigment of double oxides of tin and niobium

[0177] - Co3(P04)?

[0178] - L1C0PO4

[0179] - CoAl?Û4

[0180] - Cr?O3

[0181] - TiO?

[0182] - Black pigment PBk28 (Copper chromite black spinel)

[0183] - and their mixtures.

[0184] Decors

[0185] According to one embodiment, the layer(s) (3b) is (are) continuous and covers the entire layer (3a) (see Figure 1).

[0186] According to another embodiment, the layer(s) (3b) do(es) not cover(s) the entire layer (3a) and form(s) at least one decoration (see Figure 2). Advantageously, the layer(s) (3b) compose(s) several decorations, one (i) comprising one or more thermochromic pigment(s) and the other (j) comprising at least one temperature reference pigment composition (see Figure 3).

[0187] According to one embodiment, each of the two decorations (i) and (j) is presented in the form of adjacent non-overlapping patterns. For example, each decoration is represented by different geometric patterns distributed uniformly over the entire surface and alternating with respect to each other (see Figure 4A).

[0188] According to another embodiment, the two decorations (i) and (j) are partially overlapping. For example, each decoration is represented by different geometric patterns distributed uniformly over the entire surface and partially overlapping (see Figure 4B).

[0189] Preferably, the two decorations (i) and (j) are overlapping, either because one of the two decorations is a continuous layer and the other decoration covers it in the form of patterns, or because the two decorations (i) and (j) are in the form of overlapping patterns (see Figure 4C).

[0190] Sequins

[0191] The flakes usable in the context of the present invention may be independently chosen from mica flakes, coated or not, silica flakes, coated or not, aluminum flakes, coated or not, iron oxide flakes, coated or not. Mica or silica flakes coated with titanium dioxide. The flakes usable in the context of the present invention may be treated to give a particular color effect.

[0192] Advantageously, the flake(s) is / are particles chosen from the group consisting of particles of mica, aluminum, mica coated with titanium dioxide or mixtures thereof.

[0193] Hologram sequins

[0194] Advantageously, the glitter(s) is / are hologram glitter, i.e. a mixture of magnetizable particles and non-magnetizable particles.

[0195] The magnetizable particles may advantageously be particles comprising at least one ferromagnetic metal. These magnetizable particles may be of a homogeneous nature, i.e. made of the same material, or of a composite nature, i.e. these magnetizable particles have a core-shell structure, in which the ferromagnetic metal is found in the core and / or in 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 protection against corrosion during the steps of implementing the coating, or else plastic flakes coated with iron oxide Fe2O3, or flakes whose core is made of ferromagnetic metal and the shell is formed of a plastic material or a sol-gel material.

[0196] According to one embodiment, a portion of said magnetizable particles is oriented so as to form a three-dimensional decoration.

[0197] Advantageously, the mixture of magnetizable particles and non-magnetizable particles represents between 1% and 5% by weight of the weight of the layer, preferably between 2% and 3% by weight.

[0198] Advantageously, the percentage of non-magnetizable particles in the mixture of magnetizable particles and non-magnetizable particles is between 15% and 40% by weight relative to the total weight of the mixture of magnetizable particles and non-magnetizable particles.

[0199] Advantageously, the magnetizable particles have a dimension D50 less than or equal to 23 pm.

[0200] The term “D50” means, within the meaning of the present invention, the maximum dimension presented by 50% of the particles by number.

[0201] Advantageously, the non-magnetizable particles have a dimension D90 of between 20% and 250% of the dimension D90 of the magnetizable particles.

[0202] The term “D90” means, within the meaning of the present invention, the maximum dimension presented by 90% of the particles by number.

[0203] Advantageously, the magnetizable particles and / or the non-magnetizable particles are surface-colored. Advantageously, the non-magnetizable particles consist of mica, aluminum, or mica coated with titanium dioxide.

[0204] Advantageously, the magnetizable particles consist of iron, iron oxide, iron-coated aluminum, or iron-coated mica, the iron being in ferritic form.

[0205] SILICONE RESINS

[0206] In the text of the description, the expression "silicone resin" is used interchangeably to refer to the silicone before its crosslinking or after its crosslinking. In the text of the description, the expression "silicone" designates an organopolysiloxane material. Crosslinking is the step which makes it possible to transform the silicone into an insoluble material, for example by polyaddition, polycondensation or dehydrogenation. Crosslinking is carried out from precursors which are generally silicone oils or resins, which crosslink to obtain a three-dimensional network forming a material called silicone resin, in the description.

[0207] This crosslinking can be done by thermal activation, or chemical activation using a catalyst, such as platinum.

[0208] The silicone resins can be obtained from precursors, advantageously soluble in a solvent or in emulsion in water, such as oils or crosslinkable resins, in particular chosen 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 capacity to crosslink in order to obtain a silicone resin which is characterized by its insolubility and its substantially solid form.

[0209] Advantageously, these precursors are polymeric or oligomeric, either in the form of silicone oils with a variable degree of branching, or in the form of silicone resins with a variable degree of pre-crosslinking or copolymers of silicone resins such as silicone-polyester, silicone-alkyd, silicone-polyurethane, silicone-epoxy resins, or in the form of a mixture of silicone oils, silicone resins and copolymers of silicone resins. 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 (in particular methoxy, ethoxy, butoxy) functional groups as substituents of silicon atoms.

[0210] Advantageously, the silicone resin(s), obtained after crosslinking their precursors, i.e. crosslinked, is / are chosen from the group consisting of methyl silicone and / or phenyl silicone and / or methyl-phenyl-silicone resins, methyl silicone-polyester resin (copolymers), phenyl silicone-polyester resin (copolymers), methyl-phenyl silicone-polyester resin (copolymers), silicone-alkyd resin (copolymers), modified silicone resin and mixtures thereof.

[0211] Advantageously, the silicone resin(s) is / are chosen from the group consisting of methyl silicone and / or phenyl silicone and / or methyl-phenyl-silicone resins, methyl silicone-polyester resin (copolymers), phenyl silicone-polyester resin (copolymers), methyl-phenyl silicone-polyester resin (copolymers), silicone-alkyd resin (copolymers), modified silicone resin and mixtures thereof.

[0212] Silicone resins can be obtained from precursors, notably chosen 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.

[0213] The silicone resin forms a network which can be made up of a combination of 4 simple organosiloxane units called M, D, T and Q depending on the degree of substitution by oxygen of the silicon atom, as described in the following table, where R is an organic substituent described below. Table 2

[0214] The organopolysiloxane material or polymer is obtained by crosslinking from precursors which can be monomeric or polymeric, or intermediately which can be oligomeric. The organopolysiloxane polymer can also be obtained from a mixture of these different kinds of precursors. When the network contains a higher number of T and Q units, than D, the crosslinking density is higher. The distribution between the M, D, T and Q units depends on the chemical structure of the precursors, in particular on this M, D, T, Q distribution within the precursors.

[0215] The polymeric precursors are organopolysiloxanes. These macromolecules are formed from 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.

[0216] Organopolysiloxanes can be either linear or slightly branched (majority of D groups), or branched or highly branched (majority of T and Q groups). Linear or poorly 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 level of the individual macromolecule and are called silicone resins. At room temperature, the resins are substantially in solid form, or in liquid form, provided in particular that they have a fairly low molecular weight, in the form of a solution in a solvent or in the form of an aqueous emulsion. They can be copolymerized with organic polymers or oligomers not containing silicon, chosen in particular from polyesters, acrylics, alkyds, polyurethanes, epoxy resins. TJ

[0217] When the crosslinking is a hydrolysis-polycondensation: it is carried out thanks to the reactive hydroxy or alkoxy functions, in particular methoxy, ethoxy or butoxy, present on the organopolysiloxane.

[0218] When the crosslinking is a polyaddition (or hydrosilylation): it is carried out 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.

[0219] All these reactive functions are present on each organopolysiloxane in number of at least one and can be present in number of 2, 3, or more ... as much as the molecular structure allows. Silicone oils containing at least one reactive function are called "reactive oils". The reactive functions can be found either at the end of the macromolecular chain (termination), or distributed over the chain.

[0220] Silicone-polyester resins in particular have silicone / polyester mass ratios of, 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.

[0221] Linear PDMS silicone oils, pure or pre-emulsified in water, are characterized firstly by their molecular mass, which is a direct increasing function of the viscosity of the pure oil. They are then characterized by the presence or absence of reactive functions, for example hydroxyls 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, having at least one reactive function, preferably at least 2, which can be placed at the end of the chain.

[0222] Polymer 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, trimethylsiloxane-terminated dimethylsiloxane copolymer, MQ resin hydride, and the like, as well as combinations thereof.Polymeric precursors reacting by hydrolysis-polycondensation, whether silicone resins or silicone oils, may include, for example, poly(methylsilsesquioxanes), poly(propylsilsesquioxanes), poly(phenylsilsesquioxanes), polydimethylsiloxane (PDMS), trimethylsilyl-terminated polydimethylsiloxane (PDMS), hydroxyl-terminated polydimethylsiloxane (PDMS), silanol-terminated polydimethylsiloxane (PDMS), silanol-terminated polyphenylsiloxane (PDMS), silanol-terminated diphenylsiloxane-dimethylsiloxane copolymer, poly(2-acetoxyethylsilsesquioxanes), organo-modified alkoxysilanes and their oligomers, and all similar macromolecules and their mixtures.

[0223] The organopolysiloxane material or polymer may 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 comprising a number of reactive functions as described above greater than 2, advantageously much greater than 2, may be added to the mixture as a “co-binder” in order to promote a high crosslinking density of the organopolysiloxane polymer finally obtained.

[0224] Monomeric, oligomeric and / or polymeric precursors, in particular silicone resins, copolymerized or not with an organic polymer, act as a polymeric binder in order to obtain the solid organopolysiloxane polymer combined with the thermoplastics of each layer.

[0225] Silicone oil-type organopolysiloxane precursors can be considered additives if they are added in small amounts (typically between 0.1 and 5% dry) to the overall formulation of a layer, independently of other components for the formation of the solid organopolysiloxane polymer.

[0226] Crosslinking may require a catalyst:

[0227] - In the case of crosslinking organopolysiloxanes by hydrolysis-polycondensation, the formula may include a metal 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 dibutyl tin laurate. - In the case of crosslinking organopolysiloxanes by hydrosylilation, the addition of a catalyst may be necessary: ​​this may be, for example, platinum or a suitable platinum-based catalyst such as the Karstedt catalyst or the Ashbys catalyst.

[0228] A crosslinking agent, for example carrying Si-H bonds, may be present.

[0229] PREFERRED ARCHITECTURES

[0230] According to a variant, the intermediate layer(s) (3b) is(are) made up of:

[0231] • one or more coloring agent(s), in particular pigments and / or glitter, advantageously holograms,

[0232] • one or more thermoplastic polymer(s) advantageously chosen from polyamideimide (PAI), polyimide (PI), polyetherimide (PEI), polybenzymidazole (PBI), polyethersulfone (PES), polyphenylene ether sulfone (PPSU), polyarylether ketone (PAEK), and mixtures thereof,

[0233] • from 0 to 10% of charges,

[0234] • from 0 to 20% additives,

[0235] • optionally one or more silicone resin(s).

[0236] According to another particular variant, the intermediate layer(s) (3b) is (are) made up of:

[0237] • one or more coloring agent(s), in particular pigments and / or glitter, advantageously holograms,

[0238] • one or more thermoplastic polymer(s) advantageously chosen from polyamideimide (PAI), polyimide (PI), polyetherimide (PEI), polybenzymidazole (PBI), polyethersulfone (PES), polyphenylene ether sulfone (PPSU), polyarylether ketone (PAEK), and mixtures thereof,

[0239] • from 0 to 10% of charges,

[0240] • from 0 to 20% additives,

[0241] • one or more silicone resin(s).

[0242] According to a particular embodiment, the coating comprises two intermediate layers (3b), including at least one decorative layer. Advantageously, the layer(s) (3b) compose several decorations, one (i) comprising one or more thermochromic pigment(s) and the other (j) comprising at least one temperature reference pigment composition. Preferably, the intermediate layer(s) (3b) only partially cover the primer layer (3a).

[0243] METAL SUBSTRATE

[0244] Advantageously, said metal substrate (2), also called support, is a substrate made of aluminum, stainless steel, cast iron or aluminum, iron, titanium or copper.

[0245] For the purposes of the present invention, aluminum means a metal consisting of 100% aluminum or an aluminum alloy.

[0246] Advantageously, the metal substrate (2) is an aluminum substrate, a stainless steel substrate or a multi-layer metal substrate. The metal substrate (2) may be a two-layer or three-layer substrate, these multi-layers being able to be obtained for example by co-rolling, by hot diffusion under load (solid state bonding) or by hot or cold impact bonding.

[0247] Preferably, the metal substrate (2) comprises alternating layers of metal and / or metal alloy.

[0248] According to one embodiment, the metal substrate (2) is an aluminum alloy substrate, a stainless steel substrate or a multi-layer metal substrate whose face (2a) is made of aluminum alloy or stainless steel.

[0249] Preferably, the metal substrate (2) is an aluminum substrate.

[0250] Advantageously, the thickness of the metal substrate (2) is between 0.5 mm and 10 mm.

[0251] Advantageously, the face (2a) of the metal substrate (2) has previously undergone a surface treatment making it possible to improve the adhesion of the coating to said substrate.

[0252] According to one embodiment, the surface of the face (2a) of the metal substrate (2) has undergone a surface treatment, said surface treatment being a chemical attack, brushing, hydration, sandblasting, shot blasting, a physicochemical treatment of the plasma or corona or laser type, a chemical activation or a combination of these different techniques.

[0253] Advantageously, the face of the substrate (2a) on which the coating (3) according to the invention will be applied can be treated so as to increase its specific surface area; for an aluminum substrate, this treatment can be done by anodization (creation of a tubular alumina structure), by chemical attack, by sandblasting, by brushing, by shot blasting or by adding material by means of a technology such as thermal projection (flame, plasma or arc spray). Other metal substrates can also be polished, sandblasted, brushed, micro-blasted or receive an addition of material by means of a technology such as thermal projection (flame, plasma or arc spray).

[0254] As metallic substrates which can be used in the present invention, mention may advantageously be made of anodized or non-anodized aluminum substrates, optionally polished, brushed, sandblasted, shot-blasted or micro-blasted, anodized or non-anodized aluminum alloy substrates, optionally polished, brushed, sandblasted or micro-blasted, steel substrates, optionally polished, brushed, sandblasted, shot-blasted or micro-blasted, stainless steel substrates, optionally polished, brushed, sandblasted or micro-blasted, cast steel, aluminum or iron substrates, and copper substrates, optionally hammered or polished.

[0255] Advantageously, the substrate may be chosen from substrates comprising ferritic stainless steel / aluminum / austenitic stainless steel layers, substrates comprising stainless steel / aluminum / copper / aluminum / austenitic stainless steel layers, cast aluminum, aluminum or aluminum alloy caps lined with an outer base of stainless steel, metallic co-laminated substrates, for example two-layer co-laminated substrates comprising a stainless steel layer (for example intended to constitute the inner face of the article) and a layer of aluminum or aluminum alloy, anodized or not (for example intended to constitute the outer face of the article).

[0256] Advantageously, the average arithmetic roughness Ra of the surface of the face (2a) of the metal substrate (2) is greater than or equal to 1 pm.

[0257] The arithmetic mean roughness Ra is measured using a roughness meter according to ISO 4287. Ra represents the arithmetic mean of the deviations from the mean. The surface topography can be studied in particular with a profilometer with a probe equipped with a fine stylus equipped with a diamond tip, or with an optical metrology device such as Altisurf®, in which a chromatic confocal sensor allows a contactless measurement. The study of this surface topography makes it possible to define the arithmetic mean roughness Ra.

[0258] PROCESS

[0259] 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: a) a step of providing a metal substrate (2) comprising two opposite faces; c) optionally, a step of treating at least one face (2a) of the metal 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 the layers (3a) (3b) of the coating (3); e) optionally a drying step between 50°C and 150°C after applying each of the layers (3a) (3b); f) optionally a step of baking the element obtained in step d) or e) at a temperature between 250°C and 420°C; g) a step of applying the finishing layer (3c) to the element obtained in step d), e) or f);h) optionally a step of cooking the element obtained in step g) at a temperature between 250°C and 420°C;

[0260] 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: a) a step of providing a metal substrate (2) in the form of a substantially flat metal substrate comprising two opposite faces or a support (2) of convex or hollow shape defining a concave inner face (21) and a convex outer face (22);b) where appropriate, when a metal substrate in the form of a substantially flat metal substrate is provided during step (a), a step of shaping said substrate to give it the shape of a support (2) of convex or hollow shape defining a concave inner face (21) and a convex outer face (22), said step (b) being carried out either before step (a), or before step (d) of producing the layers (3a) and (3b) of the coating (3), or after step (f) of baking and before step (g) of producing the finishing layer or after step (g); c) optionally, a step of treating at least one face (2a) of the metal 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 the layers (3a) (3b) of the coating (3); e) optionally a drying step between 50°C and 150°C after application of each of the layers (3a) (3b);f) optionally a step of baking the element obtained in step d) at a temperature between 250°C and 420°C; g) a step of applying the finishing layer (3c) to the element obtained in step d), e) or f); h) optionally a step of baking the element obtained in step g) at a temperature between 250°C and 420°C.;

[0261] Advantageously, during step d), the layer(s) (3a) and (3b) is / are applied by pad printing, electrostatic powdering, spraying, screen printing, roller application or digital printing, preferably by spraying. Advantageously, the spraying is carried out in solvent or aqueous phase.

[0262] Advantageously, during step g), the finishing layer (3c) is applied by electrostatic powdering, spraying, screen printing, spray gun, doctor blade, coating cylinder, brush, roller application or digital printing, preferably by spraying.

[0263] According to an advantageous arrangement of the invention, the finishing layer (3c) is applied to the coated support at a deposition rate of less than or equal to 5 g / m 2 , preferably between 0.1 and 2.5 g / m 2 , even more preferably between 0.2 and 2 g / m 2 .

[0264] Advantageously, the method according to the invention comprises a step of crosslinking g') of the finishing layer (3c) subsequent to or simultaneously with step g).

[0265] According to a variant, the crosslinking of the liquid silicone varnish composition applied to the coated support can generally be activated by heat treatment, at a temperature between 50 and 400°C, preferably between 50 and 300°C, obviously taking into account the maximum resistance of the support to heat. Advantageously, the crosslinking (g') of the varnish of the finishing layer (3c) is carried out at a temperature of 300°C for a period of 10 min.

[0266] Advantageously, the higher the crosslinking temperature, the shorter the crosslinking time.

[0267] According to one embodiment, the crosslinking step g') does not require heat treatment, in particular because the support is hot at the time of application of the varnish (step g).

[0268] According to one embodiment, when at least one of the organopolysiloxanes of layer (3c) carries reactive thiol (SH) functions, the crosslinking step g') can be carried out under UV irradiation using a radical initiator activated by UV irradiation such as for example lrgacure®651 (2,2-Dimethoxy-2-phenylacetophenone).

[0269] The method may also comprise an additional step g”) of crosslinking the composition applied in step g), by UV irradiation.

[0270] Advantageously, the steps of the method according to the invention make it possible to coat the metal support (2) with a coating (3) formed by the layers (3a), (3b) and (3c). Generally, these layers are wet when they are applied. By wet layer, it is understood within the meaning of the present invention that the layer comprises all or part of its solvents.

[0271] Advantageously, the top coat (3c) is a thin, protective, hard, smooth, shiny and transparent surface coat.

[0272] For the purposes of the invention, the finishing layer (3c) has, for example, a substantially homogeneous thickness less than or equal to 10 μm, preferably less than 5 μm.

[0273] The thickness of the finishing layer (3c) is advantageously between 0.1 pm and 10 pm, preferably between 0.5 pm and 5 pm, even more preferably between 1 and 2 pm.

[0274] According to a variant, it is possible to provide several layers (3c) deposited one on top of the other. The layer (3c) is obtained from a composition which is liquid when applied. The viscosity of the composition for the layer (3c) is adjustable by dilution with solvents depending on the deposition processes used.

[0275] The composition for the layer (3c) may comprise a solvent. Advantageously, when the composition for the layer (3c) comprises at least one organopolysiloxane bearing reactive silyl hydride (Si-H) functions, the solvent is an aliphatic solvent. Advantageously, when the composition for the layer (3c) comprises at least one organopolysiloxane bearing reactive thiol (SH) functions, the solvent is an aliphatic or alcoholic solvent. Advantageously, the aliphatic solvent is chosen from the group consisting of linear or cyclic aliphatic hydrocarbons, the carbon number of which is between 5 and 10, and mixtures thereof.

[0276] The composition for layer (3c) may thus comprise a solvent present at a content 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 for layer (3c).

[0277] Surprisingly, a composition for the layer (3c) comprising a very high solvent content makes it possible to obtain layers (3c) which, after crosslinking, have a very thin thickness while being homogeneous and which are capable of making non-stick or improving the non-stick of a coating (3) applied to the face (2a) of the support (2) of a heating element (1) for a household article.

[0278] Particularly advantageously, the solvent content of the composition for layer (3c) is greater than or equal to 70% or 80% by weight relative to the weight of the liquid composition for layer (3c).

[0279] Particularly advantageously, the solvent content of the composition for layer (3c) ranges from 70% to 90% or from 80% to 90% by weight relative to the weight of the liquid composition for layer (3c).

[0280] Shaping is also called stamping.

[0281] When the shaping step precedes the application d) of the coating, the coating is preferably carried out by spraying. 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.

[0282] ARTICLE

[0283] 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 method of the invention.

[0284] According to one embodiment, this household item is a cooking item or an electrical cooking appliance and the layer (3c) forms a cooking surface (5).

[0285] In this case, layer (3c) is advantageously transparent.

[0286] In this case, the coloring agent of layer (3c) is advantageously glitter.

[0287] Advantageously, the culinary article (100) according to the invention is chosen from the group consisting of saucepan, frying pan, skillets or caquelons for fondue or raclette, stewpot, wok, sauté pan, crepe pan, grill, griddle, pot, casserole dish, cooker or bread machine bowl, culinary mold, molds and plates for pastry, barbecue plates and grills, preparation bowls.

[0288] According to one embodiment, the culinary article (100) comprises a heating face (6) intended to be placed in contact with an external heating source, the heating face (6) being opposite the cooking surface (5) intended to be placed in contact with the food during cooking.

[0289] According to embodiments, the layer (3c) is intended to be placed in contact with a heating source.

[0290] The cooking article according to the present invention may in particular be a cooking article of which one of the two opposite faces of the substrate is an inner face, possibly concave, intended to be arranged on the side of food likely to be introduced into or onto said article, and of which the other face of the substrate is an outer face, possibly convex, intended to be arranged towards a heat source. 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 griddle, electric cooker, bread machine, electric pressure cooking appliance, waffle makers, rice cookers and jam makers.

[0291] The electrical 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).

[0292] According to one embodiment, the household item according to the invention is a small heating household appliance.

[0293] It may be an iron and the coated heating element is the soleplate of the iron or a hair care article and the coated heating element is one of the heating plates of said article.

[0294] EXAMPLES

[0295] The aims, aspects and advantages of the present invention will be better understood from the description given below of a particular embodiment of the invention presented by way of non-limiting example.

[0296] Of course, the invention is in no way limited to the embodiment described and illustrated, which has been given only as an example. Modifications remain possible, in particular from the point of view of the constitution of the various elements or by substitution of technical equivalents, without departing from the scope of protection of the invention.

[0297] Examples of culinary article production

[0298] The coating is carried out flat on aluminum discs, by screen printing or by spraying.

[0299] The coating is carried out as follows:

[0300] - each layer (3a), where applicable (3b), is coated by screen printing;

[0301] - the varnish layer (3c) is spray-coated. 1. Examples and counter-example of coating (3) with a layer (3a) and, if applicable, a layer (3b) based on PEAK as well as a varnish layer (3c)

[0302] Raw materials

[0303] Aromatic Polymers PolyArylEtherKetone

[0304] Aqueous dispersion of PEEK (Poly ether ether ketone) supplied by the company VICTREX under the name VICOTE Coatings F804 “Vicote F804”: particle size d50 = 10 pm; dry extract between 35.5 and 39%; pH between 9.6 and 11.9; viscosity of approximately 11 sec DIN Cup n°6.

[0305] Aromatic thermoplastic polymers

[0306] PolyEtherSulfone (PES) powder resin, micronized grade VERADEL 3100 UFP from SOLVAY, polymer powder with a d50 < 40 pm.

[0307] Heterocyclic thermoplastic polymers

[0308] Polyamide imide (PAI) powder resin: TORLON AI10LS from Solvay, powder containing 90% dry extract in N-methylpyrrolidone (NMP / Water).

[0309] Silicone resins

[0310] - RS1: Methyl ethoxy functionalized organopolysiloxane resin in aqueous emulsion, Viscosity at 25 °C Approx. Approx. 1500 mPas, Solids content = 52%

[0311] - PDMS_1: Polydimethylsiloxane (PDMS) resin in aqueous emulsion PDMS functionalized, Solid content 62%

[0312] Co-Solvent

[0313] - High boiling point alcohol: MPG (monopropylene glycol)

[0314] - Low boiling point alcohol: IPA (isopropanol)

[0315] Additives

[0316] - Base for adjusting the pH and solubilizing certain additives: for example AMP90 or other such as ammonia solution, triethanolamine, etc.

[0317] - Antifoam: Moussex 7114HL from Synthon

[0318] Other additives

[0319] Acrylic resin:

[0320] - Rohagit SD 15: 30% acrylic polymer solution in aqueous phase or Synthomer

[0321] - Modarez FA365 from Synthron (anionic acrylic resin), or other type and / or grade Reinforcing fillers

[0322] - Aerosil R972 (Evonik): Post-treated dimethyl dichlorosilane silica fume, specific surface area (BET) = 90 to 130 m 2 / g

[0323] - Alumina: CAHPF 240 d50 = 45-50 pm from Alteo at 100%

[0324] - Graphene: Graphen from Carbon Waters, graphene in dispersed form

[0325] - Silica: Levasil CC301, surface-modified colloidal silica in the form of an aqueous dispersion of nanoparticles with a dry extract of 30%

[0326] - parylene red

[0327] - thermochromic pigments: bismuth oxide or commercial pigments based on mixed bismuth and vanadium oxide

[0328] - carbon black:

[0329] Sicopal® black K 0098 FK (Sun Chemical)

[0330] Derussol VDP 641: Black pigment concentrate in aqueous phase

[0331] The aluminum discs are an annealed 4006 alloy, 3.4 mm thick and 340 mm in diameter. They have been brushed (roughness Ra approximately 2 pm).

[0332] In Examples 1.1 to 1.8 below, the baking of layers (3a) and (3b) before the application of the top coat (3c) is carried out in an oven between 250 and 380°C for 30 to 45 minutes, then the discs are left to cool.

[0333] Example 1.1

[0334] The coating comprises a layer (3a) obtained by screen printing coating with a thickness of 30 μm to 40 μm and a layer (3c) obtained by spray coating with a thickness of 1 to 2 μm.

[0335] Layer (3a):

[0336] The PEAK ratio is such that the PEEK resin is 100%.

[0337] Table 3 gives the composition of the wet formula for layer (3a). Table 3

[0338] Viscosity is 12000 to 13000 cP, measured on Brookfield at 10 rpm, spindle #4.

[0339] The pH is between 9.0 and 10.5.

[0340] Layer (3d):

[0341] Layer (3d) is obtained after crosslinking the following composition expressed in relative part in dry mass: an organopolysiloxane carrying reactive vinyl functions (-CH=CH2): 100 parts, another organopolysiloxane carrying reactive silyl hydride functions (Si-H): 8 parts, and a metal catalyst: 6 parts.

[0342] This dry composition above is mixed with a solvent to obtain a dry extract of the order of 10 to 20% by mass.

[0343] After applying the layer (3d), the assembly is placed in an oven at 300°C for 30 to 45 minutes in order to dry and then crosslink the layer (3d), then the discs are left to cool.

[0344] Example 1.2

[0345] The coating comprises a layer (3a) identical to the layer (3a) according to example 1.1, a layer (3d) identical to the layer (3d) according to example 1.1, as well as an intermediate layer (3b) representing a decoration deposited by pad printing in interlayers with an architecture according to figure 3.

[0346] Layer 3b (j) is a thermochromic decoration and layer 3b (i) is a thermostable decoration.

[0347] Example 1.3

[0348] The coating comprises: a layer (3a) identical to the layer (3a) according to example 1.1 except for its thickness between 10 pm and 20 pm, a layer (3d) identical to the layer (3d) according to example 1.1, and an intermediate layer (3b1) whose composition is shown in the table below. The layer (3b1) is obtained by screen printing coating and has a thickness of 10 pm to 20 pm.

[0349] Layer (3b1):

[0350] The PEAK / heterocyclic polymer ratio is such that PEEK / PAI = 70 / 30 by weight.

[0351] The sum of thermoplastic polymers (PEEK + PAI) in solid phase after curing in the coating is 76.4% by weight.

[0352] The filler content (pigment + reinforcing fillers) in the baked coating is 23.1% by weight.

[0353] Table 4 Example 1.4

[0354] The coating comprises: a layer (3a) identical to the layer (3a) according to example 1.3, a layer (3d) identical to the layer (3d) according to example 1.1, and an intermediate layer (3b2) whose composition is shown in the table below. The layer (3b2) is obtained by screen printing coating and has a thickness of 10 pm to 20 pm.

[0355] Layer (3b2):

[0356] The PEAK / aromatic polymer ratio is such that PEEK / PES = 90 / 10 by weight.

[0357] The sum of thermoplastics (PEEK + PES) in solid phase after curing in the coating is 75.5% by weight.

[0358] The filler content (pigment + reinforcing fillers) in the baked coating is 24% by weight.

[0359] Table 5

[0360] Example 1.5

[0361] The coating comprises a layer (3a) identical to that of example 1.1 and a layer (3c2) obtained by spray coating with a thickness of 1 to 2 μm.

[0362] Layer (3c2):

[0363] Layer (3c2) is obtained after crosslinking the following composition expressed in relative part in dry mass: an organopolysiloxane carrying reactive vinyl functions (-CH=CH2): 100 parts, another organopolysiloxane carrying reactive thiol functions (SH): 8 parts, and a radical initiator: 15 parts.

[0364] This dry composition above is mixed with a solvent to obtain a dry extract of the order of 10% to 20% by mass.

[0365] After applying the layer (3c2), the whole thing is put in an oven at 100°C for 20 minutes to dry and then crosslink the layer (3c2) and then in an oven at 300°C for 20 minutes to finalize the cooking. Finally, the discs are left to cool.

[0366] Example 1.6

[0367] The coating comprises a layer (3a) identical to the layer (3a) according to example 1.1, a layer (3c2) identical to the layer (3c2) according to example 1.5, as well as an intermediate layer (3b) (identical to that of example 1.2) representing a decoration deposited by pad printing in interlayers with an architecture according to figure 3.

[0368] Layer (3b) (j) is a thermochromic decoration and layer (3b) (i) is a thermostable decoration.

[0369] Example 1.7

[0370] The coating comprises: a layer (3a) identical to the layer (3a) according to example 1.1 except for its thickness between 10 pm and 20 pm, a layer (3c2) identical to the layer (3c2) according to example 1.5, and an intermediate layer (3b1) identical to the layer (3b1) of example 1.3.

[0371] Example 1.8

[0372] The coating comprises: a layer (3a) identical to the layer (3a) according to example 1.7, a layer (3c2) identical to the layer (3c2) according to example 1.5, and an intermediate layer (3b2) identical to the layer (3b2) of example 1.4. Counter-'

[0373] The coating is made in 2 identical layers by screen printing coating.

[0374] A liquid coating based on an aqueous PEEK dispersion from VICTREX, PEEK dispersion: F804 is applied by spraying. An initial sintering step at 380°C of this layer for 30 minutes is followed by cooling to room temperature.

[0375] The thickness of this first layer is between 10 pm and 20 pm.

[0376] Once the surface of this coating has cooled to room temperature, the same aqueous PEEK dispersion is sprayed onto the first layer. A second sintering step at 380°C of this layer for 30 minutes is followed by cooling to room temperature.

[0377] The coating has a very rough surface to the touch and a thickness of between 40 pm and 60 pm.

[0378] 2. Examples of coating (3) with one layer (3a) and 2 layers (3ba and 3bb) based on

[0379] PES, as well as a layer of varnish (3c)

[0380] Materials

[0381] PES Resin or PolyEtherSulfone (PES) powder resin, micronized grade from SUMITOMO, polymer powder with a d50 between 11 and 15 pm.

[0382] Solvents: o propionamide

[0383] Reinforcing fillers: o Alumina, o Silicon Carbide o Pyrogenic silica, o Colloidal silica o Colloidal alumina o Mica

[0384] Thickener: o 50% acrylic polymer solution in water o hydrogenated castor oil

[0385] Silicone resins: o Methyl-phenyl silicone resin, in flakes o Methyl silicone resin, in flakes

[0386] Solvent Alcohol o di propylene glycol butyl ether (DPNB), o MPG propylene glycol

[0387] Surfactant: o Fatty alcohol polyglycol ether

[0388] Anti-foam agent o Mineral oil

[0389] Pigments: o Mica or glitter o Carbon black:

[0390] Silicone oil: o A: non-reactive o B: reactive

[0391] Other additives: o buffering agent o anionic ester in ethanol / water, wetting agent, o aqueous dispersion of polydimethylsiloxane gum, surface tension agent

[0392] On a flat aluminum disc (30 cm in diameter), previously degreased and sandblasted to obtain a roughness of 4 to 7 pm (Ra), a continuous layer 3a is deposited, chosen from the base layer compositions (3a1 and 3a2) as described below:

[0393] Layers 3a:

[0394] Layer 3a1:

[0395] Table 6 ? i

[0396] Layer 3a2:

[0397] Table 7

[0398] The thickness of this base layer 3a of the example is between 5 pm and 15 pm.

[0399] The substrate, on which the continuous base layer 3a as described above is applied, is coated with a multi-layer coating composed of a first intermediate layer 3ba (5-15 pm) which is dried at 80°C and a second intermediate layer 3bb (5-15 pm). The whole is finally heated to 300°C for approximately 10 min, i.e. the process comprises only one baking step, after the deposition of the different layers.

[0400] 3ba Layers: The compositions of the 3ba intermediate layers deposited by screen printing are as described below (3ba1 layer and 3ba2 layer). 3ba1 Layer:

[0401] Table 8

[0402] Layer 3ba2: Table 9

[0403] The compositions of the 3bb intermediate layers deposited by screen printing are as described below (layers 3bb1 to 3bb3): Layers (3bb)

[0404] Layer 3bb1:

[0405] Table 10

[0406] Layer 3bb2:

[0407] Table 11

[0408] Layer 3bb3: Table 12

[0409] Layer (3d):

[0410] Layer (3d) is identical to layer (3d) according to example 1.1.

[0411] Layer (3c2):

[0412] Layer (3c2) is identical to layer (3c2) according to example 1.5.

[0413] Examples 2.1 to 2.6 correspond to the following arrangement of layers (3):

[0414] Table 13

[0415] 3. Tests

[0416] Method for assessing drawability:

[0417] A stamping test, called the Swift test, is carried out with a Zwick stamping machine.

[0418] BPU 400.

[0419] Experimental conditions: cutting of discs with a diameter of 64 mm, 33 mm punch (Limiting Drawing Ratio = 1.9), stamping die: 40 mm

[0420] The drawability of a coating on a given substrate is translated into a binary notation:

[0421] - OK: good drawability = the adhesion of the coating to the substrate after deformation by drawing is good

[0422] - Not OK: poor drawability = the adhesion of the coating to the substrate after deformation by drawing is not good.

[0423] Stamping deformation was performed in two ways; adhesion assessment is evaluated differently depending on the deformation method. These methods are believed to give comparable results.

[0424] Laboratory scale method:

[0425] The coated aluminum substrate is deformed over a small area (a disc of approximately 10 cm in diameter is required) by a press using the "Erichsen" or "Godet" method: "Erichsen": the press deforms the surface with a conical and rounded punch to a depth of approximately 1 to 2 cm, with the coating on the outside. This deformation method also subjects the coating to stretching. If, after deformation, the coating appears very cracked or flaking / detached from the substrate, its resistance to stamping deformation is poor. To amplify the differences, a grid pattern can be made beforehand (according to ISO 2409) on the area where the punch is applied and then observed to see if many tiles have detached (with or without the application of adhesive tape).

[0426] "Godet": the press deforms the substrate with a cylindrical punch (rounded edge), with coating inside: this more closely simulates the deformation of the substrate during pan stamping, even though in the tests carried out, a 0% stretch on the skirt (the cylindrical edge) was carried out. The result is poor when we visually observe any detachment, wrinkling, ... of the coating after deformation.

[0427] Non-stick properties:

[0428] Method for evaluating the properties of the non-stick coating: PERFORMANCE EGG TEST The method for evaluating the properties of the non-stick coating is carried out using the egg test described in the AFNOR NF D 21-511 standard, paragraph 3.3.2, and implemented as follows:

[0429] The sample is cleaned, then any water remaining on the surface is wiped off.

[0430] The inner surface of the container body is dried and then oiled.

[0431] The oiled cooking container is heated on a gas stove to a temperature between 140 and 170°C.

[0432] Crack a 60 / 65 caliber egg and pour it into the center of the hot cooking container and wait for the egg to coagulate (6 to 9 minutes); remove the egg from the cooking container using a spatula, clean the coating using a damp vegetable sponge and evaluate the non-stick properties of the cooking container through this action, then record them:

[0433] Score 100: The egg can be removed completely using a plastic spatula;

[0434] Score 75: The egg does not come off completely but the coating is easily cleaned with a damp sponge,

[0435] Score 25: The egg does not come off completely and the coating is not cleaned with a damp sponge,

[0436] Rating 0: The egg does not come off and the coating cannot be cleaned with a damp sponge.

[0437] Results

[0438] The results of the drawability and non-stick performance tests are summarized below:

[0439] Table 14

[0440] The coatings according to the invention comprising a layer of varnish (3c) make it possible to obtain satisfactory hold (adhesion) of the coating when new and after three aging cycles in boiling water and oil, good resistance to corrosion and good anti-adhesion performance.

Claims

CLAIMS 1. Coated heating element (1) for a household article, comprising a metal substrate (2) coated on at least one face (2a) with a coating (3) free of fluorocarbon resin and comprising at least the following layers and in this order starting from the metal substrate (2): (3a) a primer layer comprising one or more aromatic or heterocyclic thermoplastic polymers; (3b) one or more intermediate layer(s) comprising one or more aromatic or heterocyclic thermoplastic polymers or a mixture of one or more aromatic or heterocyclic thermoplastic polymers and one or more silicone resins; (3c) a finishing layer consisting of: - an elastomer silicone obtained from at least one organopolysiloxane carrying reactive vinyl functions (-CH=CH2), and at least one other organopolysiloxane carrying reactive silyl hydride functions (Si-H) or reactive thiol functions (SH), and optionally: - one or more thermoplastic polymers, and / or - one or more additive(s), and / or - one or more coloring agents, the layer (3a) being different from at least one of the layers (3b).

2. Coated heating element (1) according to claim 1, characterized in that the content of aromatic or heterocyclic thermoplastic polymers in the primer layer (3a) is lower than the content of aromatic or heterocyclic thermoplastic polymers in the layer(s) (3b).

3. Coated heating element (1) according to claim 2, characterized in that the content of aromatic or heterocyclic thermoplastic polymers increases from the primer layer (3a) to the last layer (3b).

4. Coated heating element (1) according to any one of the preceding claims, characterized in that the content of aromatic or heterocyclic thermoplastic polymers in the primer layer (3a) represents from 50 to 75% by weight of the primer layer (3a).

5. Coated heating element (1) according to any one of the preceding claims, characterized in that the content of aromatic or heterocyclic thermoplastic polymers in the intermediate layer(s) (3b) represents from 75 to 100% by weight of said layer(s).

6. Coated heating element (1) according to any one of the preceding claims, characterized in that the thickness of the layer(s) (3a) and (3b) is between 1 μm and 100 μm, preferably between 2 μm and 30 μm, particularly preferably between 3 μm and 10 μm.

7. Coated heating element (1) according to any one of the preceding claims, characterized in that the organopolysiloxanes carrying reactive functions of the layer (3c) are silicone oils.

8. Coated heating element (1) according to any one of the preceding claims, characterized in that the thickness of the finishing layer (3c) is between 0.1 pm and 10 pm, preferably between 0.5 pm and 5 pm, even more preferably between 1 pm and 2 pm.

9. Coated heating element (1) according to any one of the preceding claims, characterized in that the silicone elastomer of the layer (3c) is obtained from at least one organopolysiloxane carrying reactive vinyl functions (-CH=CH2) and at least one other organopolysiloxane carrying reactive silyl hydride functions (Si-H) in the presence of a metal catalyst.

10. Coated heating element (1) according to any one of claims 1 to 8, characterized in that the silicone elastomer of the layer (3c) is obtained from at least one organopolysiloxane carrying reactive vinyl functions (-CH=CH2) and at least one other organopolysiloxane carrying reactive thiol functions (SH) in the presence of a radical initiator.

11. Method for manufacturing a household article comprising a coated heating element (1) with a coating (3) according to any one of the preceding claims, characterized by the following steps: a) a step of providing a metal substrate (2) in the form of a substantially flat metal substrate comprising two opposite faces or a support (2) of shape convex or hollow defining a concave inner face (21) and a convex outer face (22); b) where appropriate, when a metal substrate in the form of a substantially flat metal substrate is provided during step (a), a step of shaping said substrate to give it the shape of a support (2) of convex or hollow shape defining a concave inner face (21) and a convex outer face (22), said step (b) being carried out either before step (a), or before step (d) of producing the layers (3a) and (3b) of the coating (3), or after step (f) of baking and before step (g) of producing the finishing layer or after step (g); c) optionally, a step of treating at least one face (2a) of the metal substrate (2), to obtain a treated face (2a) promoting the adhesion of a primer layer (3a) on the support (2); d) a step of applying the layers (3a) (3b) of the coating (3);e) optionally a drying step between 50°C and 150°C after application of each of the layers (3a) (3b); f) optionally a step of baking the element obtained in step d) at a temperature between 250°C and 420°C; g) a step of applying the finishing layer (3c) to the element obtained in step d), e) or f); h) optionally a step of baking the element obtained in step g) at a temperature between 250°C and 420°C.; 12. Method according to claim 11, characterized in that, during step g), the finishing layer (3c) is applied by electrostatic powdering, spraying, screen printing, spray gun, doctor blade, coating cylinder, brush, roller application or digital printing, preferably by spraying.

13. Method according to claim 11 or 12, characterized in that it comprises a step of crosslinking g') of the finishing layer (3c) subsequent to or simultaneously with step g).

14. Method according to claim 13, characterized in that the crosslinking g') of the finishing layer (3c) is carried out at a temperature of 300°C for a duration of 10 min.

15. Household article comprising a coated heating element (1) according to any one of claims 1 to 10 or obtainable according to any one of claims 11 to 14.

16. Household article according to claim 15 characterized in that it is a culinary article or an electrical cooking appliance and in that the layer (3c) forms a cooking surface (5).

17. Household article according to claim 16, characterized in that the coloring agent of the layer (3c) is glitter.

18. Household article according to claim 15, characterized in that it is a culinary article or electrical cooking appliance and in that the layer (3c) is intended to be placed in contact with a heating source.

19. Household article according to any one of claims 15 to 18, characterized in that it is a culinary article (100) chosen from the group consisting of saucepan, frying pan, skillets or caquelons for fondue or raclette, stewpot, wok, sauté pan, crepe maker, grill, plancha, pot, casserole dish, cooker or bread machine bowl, culinary mold, molds and plates for pastry, barbecue plates and grills, preparation bowls.

20. Household article according to any one of claims 15 to 18, characterized in that it is an electric cooking appliance (200) chosen from the group consisting of electric crepe maker, electric raclette appliance, electric fondue appliance, electric grill, electric griddle, electric cooker, bread machine, electric pressure cooking appliance, waffle makers, rice cookers and jam makers.

21. Household article according to claim 15 characterized in that it is a small heating household appliance.

22. Household article according to claim 21 characterized in that it is an iron and that the coated heating element (1) is the soleplate of the iron or a hair care article and that the coated heating element is one of the heating plates of said article.

Images