sol-gel topcoat without silica with tmms or tmes

Abstract

The present invention relates to the use of a sol-gel coating for imparting non-stick properties or improving the non-stick durability of a coating (3) free of fluorocarbon resins, applied to at least one face (2a) of a support (2) for heating elements of household appliances, characterized in that said coating is free of silica and is obtained from a sol-gel composition comprising at least two polyalkoxysilane precursors, - a first precursor selected from the group of radicals R x Si(OR') 4‑x (I) in which R is a (C1-C6)-alkyl, (C2-C6)-alkenyl, (C3-C7)-cycloalkyl, (C4-C7)-cycloalkenyl, (C3-C7)-cycloalkyl-(C1-C6)-alkyl, aryl or aryl-(C1-C6)alkyl group, optionally substituted; R' is a (C1-C8)-alkyl group; and x is 0, 1, 2 or 3; and - a second precursor is TMMS (trimethylmethoxysilane) or TMES (trimethylethoxysilane) or a mixture thereof.

Description

Technical Field

[0001] This invention generally relates to the field of household appliances, including surfaces covered with a non-stick coating. More specifically, the invention is suitable for the field of non-stick coatings on cooking utensils and electric cooking equipment. The invention also relates to methods of manufacturing such utensils.

[0002] This invention addresses the technical problem of sol-gel coating formulations with improved non-stick durability. Background Technology

[0003] In the field of cooking utensils, coatings with non-stick properties applied to metal substrates or metal supports (aluminum, cast aluminum, stainless steel, cast steel, etc.) are known to have a wide variety of chemical properties.

[0004] More specifically concerning the inner surfaces of these appliances, PTFE-based fluoropolymer coatings have been known for over 50 years and are highly regarded for their excellent non-stick properties. In recent years, so-called "ceramic" coatings based on sol-gel chemistry have also appeared on the market, offering superior heat resistance and surface hardness compared to PTFE coatings, while maintaining good easy-to-clean properties.

[0005] It has been found that the non-stick properties of these sol-gel coatings decrease over time with use of cooking appliances. Those skilled in the art know that adding silicone oil can compensate for this decrease in non-stick properties. However, the durability of these appliances, especially their non-stick properties, remains limited and unsatisfactory for the user.

[0006] In addition, to obtain good mechanical properties, it is widely known and practiced by all sol-gel coating manufacturers to add colloidal silica to their coating formulations to obtain a few micrometers thick, crack-free coating with high mechanical strength in all layers of the sol-gel coating, including the top layer.

[0007] Sol-gel formulations for use in cooking appliances have been known for many years. Industrial formulations are particularly based on the hydrolysis and condensation of MTES (methyltriethoxysilane) or MTMS (methyltrimethoxysilane), adding non-reactive or reactive hydroxylated PDMS (polydimethylsiloxane) silicone oil to the bottom and top layers, always in combination with colloidal silica. The role of the silane is to form a network with good mechanical properties, while also being hydrophobic due to the presence of numerous methyl groups.

[0008] In this network, hydrophobic compounds such as PDMS oil are added, which significantly improves hydrophobicity and non-stick properties. Unfortunately, the amount of PDMS oil cannot exceed a certain threshold; exceeding this threshold causes the sol-gel coating to expel excess oil. This results in an overly greasy workpiece surface at the end of condensation due to oil seepage and release. Summary of the Invention

[0009] The applicant has developed a topcoat for sol-gel non-stick coatings that overcomes the aforementioned drawbacks.

[0010] Surprisingly, the inventors have developed a ceramic coating that offers significant benefits to consumers. In fact, cooking utensils equipped with this coating retain their non-stick properties for longer periods of use than those with other ceramic coatings.

[0011] Consumers can use their appliances for several more years. In addition to the obvious economic and ecological benefits, consumers will experience significantly increased satisfaction during use, and may also use less oil.

[0012] Furthermore, another advantage of the present invention is that the surface layer has optical properties compatible with the visual properties present in the coating.

[0013] Furthermore, another advantage of the present invention is that it unexpectedly maintains satisfactory mechanical properties and is compatible with culinary applications.

[0014] In addition, another advantage of the present invention is that the top layer can contain a greater amount of silicone oil than a standard coating without releasing the oil on the surface, which gives the coating a long-lasting non-stick property. Attached Figure Description

[0015] [ Figure 1 [A schematic diagram of the heating element according to the present invention, wherein layer (3b) is continuous and covers the entire layer (3a).] [ Figure 2 [Schematic diagram of the heating element according to the present invention, wherein layer (3b) does not cover the entire layer (3a) and forms a decoration.] [ Figure 3 [Schematic diagram of the heating element according to the present invention, wherein layer (3b) consists of two decorations (i) and (j).] [ Figure 4 ]: Schematic diagram of pattern distribution. 4A = Adjacent non-overlapping patterns. 4B = Partially overlapping patterns. 4C = Overlapping patterns.

[0016] [ Figure 5 [Schematic diagram of the cooking utensil according to the present invention] [ Figure 6 [Schematic diagram of the electric cooking device according to the present invention] Detailed Implementation definition The term "coating" refers to the entirety of all layers that adhere to and cover a metal substrate. The coating obtained according to the invention is advantageously solid; "solid" refers to the characteristics of a cohesive material, insoluble in water, common solvents, food ingredients such as aqueous or oily mixtures, even if the material can possess great hardness or great flexibility, such as an elastomer.

[0017] The term "layer" should be understood in the context of this invention as a continuous or discontinuous layer. A continuous layer (also called a monolithic layer) is a single, integral unit that forms a complete plane that fully covers the surface to which it is applied. A discontinuous layer (or non-monolithic layer) may comprise multiple parts and does not constitute a single, integral unit.

[0018] The terms "base layer," "bottom layer," "adhesive layer," or "adhesive underlayer" refer to all layers from the first layer applied directly to the support (which preferably 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. The first layer of the coating is the base layer.

[0019] The term "intermediate layer" refers to a layer that lies between one or more base layers and one or more top layers. The intermediate layer can be a "decorative" or "furnishing layer." It is not intended to come into contact with food.

[0020] The term "topcoat" or "coating" refers to a continuous surface layer applied after one or more intermediate layers when the coating comprises one or more intermediate layers, or after the base coat. The final layer of the coating is the topcoat. Typically, at least the final topcoat, or even all topcoats, is transparent to allow the underlying layers to be seen, especially when the underlying layers are decorative layers. The topcoat protects the underlying layers from mechanical damage and imparts its non-stick properties to the coating. Preferably, in the case of cooking utensils or electric cooking equipment, the final topcoat is intended for contact with food.

[0021] The term "decoration" or "decorative layer" refers to one or more continuous or discontinuous layers containing a pigment composition. Decoration can take the form of one or more patterns and one or more colors. Decoration is clearly visible to the naked eye at the distance from which a household appliance is normally used.

[0022] An "overlapping layer" refers to a layer that partially or completely overlaps. These layers can be presented in the form of partially overlapping patterns, such as concentric discs.

[0023] The term "adjacent layer" refers to layers that do not overlap. These layers can be presented in the same or different non-overlapping patterns, preferably evenly distributed.

[0024] In the context of this invention, a sol-gel coating refers to a coating synthesized from a sol-gel composition via a sol-gel pathway. The resulting coating can be organic-inorganic hybrid or entirely inorganic. The sol-gel pathway, in the context of this invention, refers to a synthetic principle involving the conversion of a solution based on a liquid-phase precursor into a solid through a series of low-temperature chemical reactions (hydrolysis and condensation). The resulting coating can be organic-inorganic hybrid or entirely inorganic.

[0025] In the context of this invention, an organic-inorganic hybrid coating refers to a coating whose network is essentially inorganic but contains organic groups, particularly due to the precursors used and the calcination temperature of the coating, or due to the incorporation of organic fillers.

[0026] In the context of this invention, a completely inorganic coating refers to a coating based on completely inorganic materials and containing no organic groups. Such a coating can be obtained via a sol-gel route, typically with a calcination temperature of at least 400°C, or from metal alkoxide and / or metal polyalkoxide precursors, typically with a calcination temperature below 400°C.

[0027] In this invention, the term "cooking utensil" should be understood as an object used for cooking and heated by an external heating system, such as a frying pan, stew pot, frying pan, round-bottomed wok, or barbecue grill. The cooking utensil is capable of transferring heat from the external heating system to the material or food in contact with it.

[0028] In the context of this invention, the term "electric cooking equipment" should be understood as a heating object with its own heating system, such as an electric crepe pan, an electric cheese grill, an electric cheese fondue, an electric grill, an electric flat baking pan, an electric cooker, a bread maker, and a pressure electric cooking device.

[0029] In this invention, weight percentages are expressed as dry weight, i.e., without solvent.

[0030] The group “(C1-C6)alkyl” or “(C1-C6)alkyl”, in the context of this invention, refers to a saturated, straight-chain or branched monovalent hydrocarbon chain containing 1 to 6, preferably 1 to 4, carbon atoms. Examples include methyl, ethyl, and propyl.

[0031] The group “(C3-C7)cycloalkyl” or “(C3-C7)cycloalkyl”, in the context of this invention, refers to a saturated cyclic hydrocarbon chain containing 3 to 7 cyclic carbon atoms. Cycloalkyl groups can be monocyclic or bicyclic. Examples include cyclopropyl, cyclopentyl, cyclohexyl, or cycloheptyl.

[0032] In the context of this invention, the term "aromatic group" refers to aryl or heteroaryl groups.

[0033] In the context of this invention, "aryl" refers to an aromatic hydrocarbon group, preferably containing 6 to 10 carbon atoms, and optionally containing one or more fused rings, such as phenyl or naphthyl. Advantageously, it is phenyl.

[0034] The group “(C2-C6)alkenyl”, in the context of this invention, refers to a straight-chain or branched monovalent hydrocarbon chain containing at least one double bond and comprising 2 to 6 carbon atoms. Examples include vinyl, propenyl, allyl, butenyl, pentenyl, or hexenyl.

[0035] The term "optionally substituted" in the context of this invention means that the group is optionally replaced by one or more, preferably one or two, atoms selected from halogen atoms, C1-C6 alkyl groups, and NR atoms. a R b COR c CO2R d CONR e R f and OR g Substituents of R, wherein R a To R g Each of the above independently represents H, (C1-C6)-alkyl, optionally substituted with a 3- to 6-membered heterocycle, which is preferably saturated, preferably contains only one heteroatom, preferably O or N, and preferably O.

[0036] Detailed description of the invention Therefore, the subject of this invention is the use of a sol-gel surface layer for imparting non-stick properties or improving the non-stick durability of a fluorocarbon-free coating (3) applied to at least one surface (2a) of a support (2) for a heating element of a household appliance, characterized in that the surface layer is silica-free and obtained from a sol-gel composition comprising at least two polyalkoxysilane precursors. - The first precursor is selected from the group of formula (I). R x Si(OR') 4-x (I) in R is (C1-C6)-alkyl, (C2-C6)-alkenyl, (C3-C7)-cycloalkyl, (C4-C7)-cycloalkenyl, (C3-C7)-cycloalkyl-(C1-C6)-alkyl, aryl, or aryl-(C1-C6)alkyl, optionally substituted; R' is (C1-C8)-alkyl; and x is 0, 1, 2 or 3; and - The second precursor is TMMS (trimethylmethoxysilane) or TMES (trimethylethoxysilane) or a mixture thereof.

[0037] By grafting these two compounds into the network, a slightly different network was obtained: The number of CH3 groups increases; The reduction in the number of SiO bonds => produces more defects to some extent; More PDMS oils can be integrated into this network.

[0038] In other words, TMMS and TMES can increase the proportion of methyl groups in the network and the maximum proportion of silicone oil that can be incorporated, thereby extending the non-stick properties of the coating.

[0039] Advantageously, the ratio between the first precursor and the second precursor is between 1:10 and 10:1, preferably between 5:1 and 1:5.

[0040] Advantageously, x is not equal to 0.

[0041] Advantageously, R is (C1-C6)-alkyl (e.g., methyl, ethyl), phenyl, or vinyl.

[0042] Advantageously, R' is (C1-C6)-alkyl, preferably (C1-C4)-alkyl, more preferably methyl or ethyl.

[0043] Advantageously, the first precursor is selected from the group consisting of methyltrimethoxysilane (MTMS), methyltriethoxysilane (MTES), dimethyldiethoxysilane, dimethyldimethoxysilane, trimethylmethoxysilane, trimethylethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, 3-aminopropyltriethoxysilane, (3-glycidoxypropyl)trimethoxysilane, allyltrimethoxysilane, and mixtures thereof.

[0044] Preferably, the first precursor is methyltrimethoxysilane (MTMS) or methyltriethoxysilane (MTES) or a mixture thereof.

[0045] Preferably, the first precursor is MTMS and the second precursor is TMMS.

[0046] Preferably, the sol-gel surface layer does not contain colloidal silica or micron-sized silica or mixtures thereof.

[0047] Advantageously, the thickness of the sol-gel surface layer is 1 to 15 µm, preferably 2 to 12 µm, and more preferably 2 to 10 µm.

[0048] According to one variant, the sol-gel composition of the surface layer does not contain colloidal metal oxides.

[0049] The sol-gel composition of the surface layer may also contain a solvent, particularly a solvent containing at least one alcohol. Solvents containing at least one alcohol are referred to below as "alcohol solvents".

[0050] The alcohol is preferably a C1-C6 alcohol. C1-C6 alcohols refer to saturated, straight-chain or branched hydrocarbon chains containing 1 to 6 carbon atoms and a hydroxyl group (-OH) attached to a carbon atom. Examples include ethanol, n-propanol, and isopropanol.

[0051] The surface layer according to the invention may further comprise at least one functionalized or non-functionalized, reactive or non-reactive silicone oil, preferably PDMS oil.

[0052] Linear PDMS silicone oils, pure or pre-emulsified, are first characterized by their molecular weight, which increases directly with the viscosity of the pure oil. Secondly, they are characterized by the presence, number, and position of reactive functional groups (e.g., hydroxyl groups on silicon atoms (silanols)). For example, reactive oils with viscosities of 50 to 20,000 mPa·s, particularly 300 to 5,000 mPa·s, can be used, having at least one, preferably at least two, reactive functional groups, which may be located at the chain ends.

[0053] Advantageously, the surface composition is obtained by adding water and an acid or base catalyst to hydrolyze the sol-gel precursor, and then by a condensation reaction to obtain the sol-gel coating composition.

[0054] The sol-gel composition of the surface layer may contain an acid catalyst, such as acetic acid, formic acid, citric acid, hydrochloric acid, tartaric acid, or mixtures thereof.

[0055] The sol-gel composition of the surface layer may contain an alkaline catalyst, such as sodium hydroxide (NaOH), potassium hydroxide (KOH), ammonia (NH4), or a mixture thereof.

[0056] The sol-gel composition of the top layer may also contain colorants, as defined in the list below.

[0057] The sol-gel composition of the top layer may also contain at least one filler, as defined in the list below.

[0058] Coated heating element Another subject of the present invention is a method for manufacturing a coated heating element (1) for use in a household appliance including a coated support (2), the method comprising the following steps: a) Provide a support member (2) having at least one surface to be coated (2a); b) Apply a coating (3) to at least one surface (2a) of the support member to be coated; c) Apply the sol-gel topcoat as described above to the coating (3).

[0059] Advantageously, in step c), the sol-gel topcoat is applied by electrostatic powder spraying, spraying, screen printing, spray gun, doctor blade, coating roller, brush, roller coating or digital printing, preferably by spraying.

[0060] Another subject of the present invention is a coated heating element (1) for a household appliance, which can be obtained according to the method described above.

[0061] coating The properties of the coating (3) are suitable for use in heating elements of household appliances.

[0062] Those skilled in the art will know how to select an appropriate coating based on the household appliance and its intended use.

[0063] Advantageously, the coating (3) comprises one or more layers. Typically, the coating (3) comprises, from the substrate (2), one or more underlayers (3a), optionally one or more intermediate layers (3b), and one or more top layers (3c).

[0064] The coating (3) does not contain fluorocarbon resin, also known as fluoropolymer or fluoropolymer. In other words, the coating (3) does not contain fluorocarbon resin. Therefore, the coating (3) does not contain and does not release perfluoroalkyl compounds and polyfluoroalkyl compounds.

[0065] When the coating (3) comprises multiple layers, they may be the same or different in terms of the properties of the components, the weight percentage of the components, the thickness, etc.

[0066] The coating (3) may include: - One or more additives, and / or, - One or more colorants, and / or - One or more fillers.

[0067] The coating (3) can be organic, inorganic or hybrid.

[0068] The coating (3) can be ceramic, such as sol-gel, polymeric, such as thermoplastic polymer, silicone resin, or enamel.

[0069] thermoplastic polymers Advantageously, the thermoplastic polymer is selected from the group consisting of aromatic thermoplastic polymers such as polyaryletherketone (PAEK), polyarylethersulfone (PAES), polyarylether sulfide (PAS) or polyphenylene ether (PPO), liquid crystal polymers, heterocyclic thermoplastic polymers and mixtures thereof.

[0070] PAEK Advantageously, the polyaryletherketone (PAEK) is selected from the group consisting of polyetherketone (PEK), polyetheretherketone (PEEK), polyetherketoneketone (PEKK), polyetheretherketoneketone (PEEKK), and polyetherketoneetherketoneketone (PEKEKK), and is particularly preferred to be PEEK.

[0071] Other aromatic thermoplastic polymers Examples of aromatic thermoplastic polymers suitable for use in this invention include polyphenylene oxide (PPO), polyarylene ether sulfone (PAES) polymers (especially polyether sulfone (PES), polyphenylene sulfone (PPSU)), polyarylene sulfide (PAS) (especially polyphenylene sulfide (PPS)), liquid crystal polymers, and mixtures thereof.

[0072] Heterocyclic thermoplastic polymers Examples of heterocyclic thermoplastic polymers suitable for the present invention include polyetherimide (PEI), polyimide (PI), polyamideimide (PAI), and polybenzimidazole (PBI), or mixtures thereof.

[0073] Advantageously, the thermoplastic polymer is selected from the group consisting of polyethersulfone (PES), polyphenylsulfone (PPSU), polyamide-imide (PAI), polyimide (PI), polyphenylene ether (PPO), polyarylene sulfide (PAS), polyetherimide (PEI), polybenzimidazole (PBI), liquid crystal polymer (LCP), polyphenylene sulfide (PPS), polyarylene ether ketone (PAEK) (including polyether ketone (PEK), polyether ether ketone (PEEK), polyether ketone ketone (PEKK), polyether ether ketone ketone (PEEKK), polyether ketone ketone (PEKEKK) and polyether ketone ether ketone ketone (PEKEKK)) and mixtures thereof.

[0074] According to one variant, PAEK is used in suspension form, in which PAEK particles have a d50 particle size of approximately 10 µm to 15 µm.

[0075] silicone resin In this specification, the term "silicone" is used interchangeably to refer to silicone before or after crosslinking. In this specification, the term "silicone" refers to an organopolysiloxane material. Crosslinking is the step of converting a silicone into an insoluble material, for example by addition polymerization, condensation polymerization, or dehydrogenation. Crosslinking begins with precursors, typically silicone oils or silicone resins, which crosslink to obtain a three-dimensional network, forming a material referred to as silicone in this specification.

[0076] This crosslinking can be achieved through thermal activation or chemical activation using a catalyst (such as platinum).

[0077] Silicone resins can be obtained from precursors that are advantageously soluble in solvents or emulsions in water, such as crosslinkable oils or resins, particularly selected from the group consisting of hydrosilylates, silicone oils containing at least one vinyl group (-CH=CH2), silicone resins or silicone-polyester (copolymers) containing at least one alkoxy group (e.g., methoxy or ethoxy), and / or silicone resins or silicone-polyester (copolymers) containing at least one alkoxy group (especially ethoxy) or hydroxyl group, and mixtures thereof. These precursors have crosslinking capabilities to obtain insoluble and substantially solid silicone resins.

[0078] Advantageously, these precursors are polymers or oligomers, and can be in the form of silicone oils with variable branching, or silicone resins or silicone copolymers with variable pre-crosslinking (such as silicone-polyester, silicone-alkyd, silicone-polyurethane, silicone-epoxy resin), or mixtures of silicone oils, silicone resins, and silicone copolymers. Silicon atoms can be substituted with alkyl (especially methyl) or aryl (especially phenyl) groups or mixtures thereof. The oil or resin preferably contains one or more (two, three, or more) hydroxyl or alkoxy (especially methoxy, ethoxy, butoxy) functional groups as substituents for the silicon atoms.

[0079] Advantageously, the silicone resin after its precursor crosslinking (i.e., after crosslinking) is selected from the group consisting of methyl silicone resin and / or phenyl silicone resin and / or methyl-phenyl silicone resin, methyl silicone-polyester resin (copolymer), phenyl silicone-polyester resin (copolymer), methyl-phenyl silicone-polyester resin (copolymer), silicone-alkyd resin (copolymer), modified silicone resin and mixtures thereof.

[0080] Advantageously, the silicone resin is selected from the group consisting of methyl silicone resin and / or phenyl silicone resin and / or methyl-phenyl silicone resin, methyl silicone-polyester resin (copolymer), phenyl silicone-polyester resin (copolymer), methyl-phenyl silicone-polyester resin (copolymer), silicone-alkyd resin (copolymer), modified silicone resin and mixtures thereof.

[0081] Silicone resins can be obtained from precursors, particularly those selected from the group consisting of: hydrides, silicone resins containing at least one vinyl group (-CH=CH2), silicone-polyester resins (copolymers) containing at least one methoxy group, and / or silicone-polyester resins (copolymers) containing at least one ethoxy group, and mixtures thereof.

[0082] The silicone resin forms a network that can be composed of a combination of four simple organosiloxane units, M, D, T, and Q, depending on the degree to which silicon atoms are substituted with oxygen, as shown in the table below, where R is an organic substituent as described below.

[0083] Organopolysiloxane materials or polymers are obtained through crosslinking. The precursors can be monomers, polymers, or oligomers in between. Organopolysiloxane polymers can also be obtained from mixtures of these different types of precursors. Higher crosslinking density occurs when the network contains a greater number of T and Q units than D units. The distribution of M, D, T, and Q units depends on the chemical structure of the precursor, particularly the distribution of M, D, T, and Q units within the precursor.

[0084] The polymer precursors are organopolysiloxanes. These macromolecules are formed from M, D, T and / or Q units, as described in the table, where R is independently alkyl (especially methyl) or aryl (especially phenyl), and Rs with different properties can coexist on the same macromolecule.

[0085] Organopolysiloxanes can be linear or slightly branched (mostly D-groups), or branched or highly branched (mostly T and Q-groups). Linear or slightly branched organopolysiloxanes are typically liquids at room temperature, more or less viscous, and are called silicone oils. Branched or highly branched (pre-crosslinked) organopolysiloxanes form networks at the individual macromolecular scale and are called silicone resins. At room temperature, the resins are essentially solid, or liquid when the molecular weight is sufficiently low, or exist as solvent solutions or aqueous emulsions. They can be copolymerized with silicone-free organic polymers or oligomers, particularly selected from polyesters, acrylic resins, alkyd resins, polyurethanes, and epoxy resins.

[0086] When crosslinking is a hydrolysis-condensation process, it occurs via reactive functional groups of hydroxyl or alkoxy groups (especially methoxy, ethoxy, or butoxy) present on the organopolysiloxane.

[0087] When crosslinking is an addition polymerization (or hydrosilylation): it proceeds through a reaction between a vinyl (-CH=CH2) reactive functional group present on one organopolysiloxane and a hydrosilylate (Si-H) reactive functional group present on another organopolysiloxane mixed with the first.

[0088] All of these reactive functional groups are present on each organopolysiloxane, with at least one, and possibly two, three, or more, depending on the molecular structure. Silicone oils containing at least one reactive functional group are called "reactive oils." Reactive functional groups can be located at the ends of the macromolecular chains (terminal groups) or distributed along the chain.

[0089] Silicone-polyester resins particularly have silicone / polyester mass ratios of, for example, 90 / 10, 80 / 20, 70 / 30, 60 / 40, 50 / 50, 40 / 50, 30 / 70, 20 / 80, and 10 / 90, advantageously between 80 / 20 and 50 / 50.

[0090] Linear PDMS silicone oils, pure or pre-emulsified, are first characterized by their molecular weight, which increases directly with the viscosity of the pure oil. Secondly, they are characterized by the presence, number, and position of reactive functional groups (e.g., hydroxyl groups on silicon atoms (silanols)). For example, reactive oils with viscosities of 50 to 20,000 mPa·s, particularly 300 to 5,000 mPa·s, can be used, having at least one, preferably at least two, reactive functional groups, which may be located at the chain ends.

[0091] Polymer precursors obtained by addition polymerization reactions may include, for example, polymethylhydrosiloxanes, vinylmethylsiloxanes, vinyl-terminated polydimethylsiloxanes (PDMS), particularly linear, vinyl-terminated diphenylsiloxane-dimethylsiloxane copolymers, hydride-terminated polydimethylsiloxanes, hydride-terminated polyphenylmethylsiloxanes, cyclic vinylmethylsiloxanes, vinyl-MQ resins, trimethylsilyl-terminated polymethylhydrosiloxanes, trimethylsiloxane-terminated methylhydrosiloxane and dimethylsiloxane copolymers, MQ resin hydrides, and combinations thereof.

[0092] Polymer precursors obtained through hydrolysis-condensation reactions, whether silicone resins or silicone oils, may include, for example, poly(methylsilsesquioxane), poly(propylsilsesquioxane), poly(phenylsilsesquioxane), polydimethylsiloxane (PDMS), trimethylsilyl-terminated polydimethylsiloxane (PDMS), hydroxyl-terminated polydimethylsiloxane (PDMS), silanol-terminated polydimethylsiloxane (PDMS), silanol-terminated polyphenylsiloxane (PDMS), silanol-terminated diphenylsiloxane-dimethylsiloxane copolymers, poly(2-acetoxyethylsilsesquioxane), organically modified alkoxysilanes and their oligomers, and all similar macromolecules and mixtures thereof.

[0093] Organopolysiloxane materials or polymers can also be obtained by crosslinking a mixture of one or more monomeric precursors and one or more of the aforementioned polymeric precursors and one or more oligomeric precursors, which can be linear, branched, or cyclic. The molecular weight of these oligomeric precursors is lower than that of the polymeric precursors. Polymers and / or oligomeric precursors containing more than two, advantageously far more than two, of the aforementioned reactive functional groups can be added to the mixture as a "co-binder" to promote a high crosslinking density in the final organopolysiloxane polymer.

[0094] Monomers, oligomers, and / or polymer precursors, particularly silicone resins, whether or not copolymerized with organic polymers, act as polymer binders to obtain solid organopolysiloxane polymers bonded to each layer of thermoplastic material.

[0095] Organopolysiloxane silicone oil-type precursors, if added in small amounts (typically 0.1 to 5% dry weight) to the entire formulation of one layer, can be considered as additives, independent of other components that form solid organopolysiloxane polymers.

[0096] Crosslinking may require a catalyst: - In the case of crosslinking organopolysiloxanes via hydrolysis-condensation, the formulation may include metal catalysts, such as metal complexes based on platinum, tin, zinc, zirconium and cerium, particularly platinum-cyclovinylmethylsiloxane complexes, tin ethylhexanoate, zinc ethylhexanoate, zirconium ethylhexanoate, cerium ethylhexanoate and dibutyltin dilaurate.

[0097] - In the case of crosslinking organopolysiloxanes by hydrogenation silanization, a catalyst may need to be added: for example, it may be platinum or a suitable platinum-based catalyst, such as a Karstedt catalyst or an Ashby catalyst.

[0098] Crosslinking agents, such as those with Si-H bonds, may be present.

[0099] Sol-gel According to one embodiment, the one or more bottom layers and the one or more optional intermediate layers are one or more sol-gel layers.

[0100] Advantageously, the composition of these layers may comprise a solution based on a liquid-phase precursor, the solution comprising a metal alkoxide type and / or a metal or metalloid polyalkoxide type sol-gel precursor.

[0101] Preferably, metal or metalloid alkoxides selected from the following group are used as precursors: - Precursors conforming to the general formula M1(OR1)n - Conforms to the general formula M2(OR2)(n-1)R 2' The precursor, and - A precursor conforming to the general formula M3(OR3)(n-2)R3'2, wherein: R1, R2, R3 or R 3' Indicates alkyl group, R 2' Indicates alkyl or phenyl, n is an integer corresponding to the highest valence state of metals M1, M2, or M3. M1, M2 or M3 represent metals or metalloids selected from Si, Zr, Ti, Sn, Al, Ce, V, Nb, Hf, Mg, B or Ln.

[0102] Advantageously, the metal alkoxide in the sol-gel composition is an alkoxysilane. Alkoxysilanes that can be used in sol-gel solutions particularly include methyltrimethoxysilane (MTMS), tetraethoxysilane (TEOS), methyltriethoxysilane (MTES), dimethyldimethoxysilane, and mixtures thereof.

[0103] Preferably, the one or more bottom layers and the one or more optional intermediate layers contain methyltrimethoxysilane (MTMS) as a sol-gel precursor.

[0104] Advantageously, the composition of the sol-gel layer comprises at least one metal alkoxide-type sol-gel precursor as described above and at least one colloidal metal oxide dispersed in the composition at least 2% by weight relative to the total weight of the composition.

[0105] Advantageously, the composition of the sol-gel layer is obtained by adding water and an acid or base catalyst to hydrolyze the sol-gel precursor, and then by a condensation reaction to obtain the sol-gel non-stick coating composition.

[0106] The composition of the sol-gel layer may contain an acid catalyst, such as acetic acid, formic acid, citric acid, hydrochloric acid, tartaric acid, or mixtures thereof.

[0107] The composition of the sol-gel layer may contain an alkaline catalyst, such as sodium hydroxide (NaOH), potassium hydroxide (KOH), ammonia (NH4), or a mixture thereof.

[0108] The composition of the sol-gel layer may also contain colorants, as defined in the list below.

[0109] The composition of the sol-gel layer may also contain at least one filler, as defined in the list below.

[0110] The composition of the sol-gel layer may also contain at least one functionalized or unfunctionalized, reactive or non-reactive silicone oil, such as polydimethylsiloxane oil (PDMS oil).

[0111] additive Advantageously, the additive is selected from the group consisting of defoamers, dispersants, wetting agents, thickeners, pH adjusters, and reactive silicone oils.

[0112] The defoamer is preferably selected from the group consisting of mineral oil, glycol, hydrocarbon, glycerol ester, propylene oxide, and emulsified fatty acids.

[0113] The surfactant is preferably selected from the group consisting of ethylene glycol ethers, ethoxylated alcohols (excluding alkylphenol ethoxylates (APE)), and gemini surfactants.

[0114] The dispersant is preferably selected from the group consisting of anionic dispersants such as fatty acid derivatives.

[0115] The thickener is preferably selected from the group consisting of acrylic or polyurethane copolymers, cellulose, and fumed silica.

[0116] The pH adjuster is preferably selected from the group consisting of Brønsted base, ammonia, amines (triethylamine, triethanolamine, etc.), hydroxides (sodium hydroxide, potassium hydroxide, etc.), and carbonates.

[0117] Advantageously, the proportion of additives in the surface layer according to the invention is less than 20% by weight relative to the total weight of the layer.

[0118] Colorant The function of a "colorant" is to change or bring about color.

[0119] Advantageously, the colorant is selected from the group consisting of thermochromic pigments, heat-stable pigments, soluble dyes, glitter sheets (preferably holographic glitter sheets) and mixtures thereof.

[0120] Advantageously, the proportion of colorant in the surface layer according to the invention (when present) is less than 10% by weight relative to the total weight of the layer.

[0121] Advantageously, the surface layer according to the invention is transparent. In this case, if it contains colorants, these colorants are glitter flakes.

[0122] Thermochromic Pigments Preferably, the thermochromic pigment is selected from Bi2O3, Fe2O3, V2O5, WO3, CeO2, In2O3, and Y. 1,84 Ca 0, 16 Ti 1,84 V 0,16 O 1,84 AgI, (Bi 1-x A x (V) 1-y M y O4, BiOC 1-z D z The group consists of: - x equals 0 or x is between 0.001 and 0.999, - y equals 0 or y is between 0.001 and 0.999. - z equals 0 or z is between 0.001 and 0.999, - C and D are selected from the group consisting of iodine, fluorine, chlorine, and bromine, and C and D are different from each other. - A and M are selected from groups composed of nitrogen, phosphorus, alkali metals, alkaline earth metals, transition metals, depleted metals, metalloids, or lanthanides. - A and M are different from each other.

[0123] Given that A and M are distinct, when: - A is an alkali metal, which can be selected from Li, Na, K, Rb, and Cs. - M is an alkali metal, which can be selected from Li, Na, K, Rb, and Cs. - A is an alkaline earth metal, which can be selected from Be, Mg, Ca, Sr, and Ba. - M is an alkaline earth metal, which can be selected from Be, Mg, Ca, Sr, and Ba. - A is a transition metal, which can be selected from Sc, Ti, Cr, Mn, Fe, Co, Ni, Cu, Y, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Ta, W, and Ir. - M is a transition metal, which can be selected from Sc, Ti, Cr, Mn, Fe, Co, Ni, Cu, Y, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Ta, W, and Ir. - A is a low-grade metal, which can be selected from Al, Zn, Ga, In, and Sn. - M is a low-growth metal, which can be selected from Al, Zn, Ga, In, and Sn. - A is a metalloid, which can be selected from B, Si, Ge, and Sb. - M is a metalloid, which can be selected from B, Si, Ge, and Sb. - A is a lanthanide element, which can be selected from La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu. - M is a lanthanide element, which can be selected from La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu.

[0124] Preferably, A and M, which are different from each other, are B and / or Mg.

[0125] Preferably, pigment (Bi) 1-x A x (V) 1-y M y O4 exists as monoclinic scheelite crystals at room temperature.

[0126] Preferably, x and y are 0, i.e., pigment (Bi) 1-x A x (V) 1-y M y O4 is bismuth vanadate (BiVO4). Advantageously, BiVO4, which has a monoclinic scheelite crystal structure at room temperature, is used.

[0127] Bismuth vanadate is a yellow inorganic compound with the chemical formula BiVO4, widely used for its coloring properties and non-toxicity. It is registered in the International Color Index database as QI Pigment Yellow 184 and is sold by companies such as Heubach (Vanadur®), BASF (Sicopal®), FERRO (Lysopac), or Bruchsaler Farbenfabrik (Brufasol®).

[0128] Heat-stabilized pigments Preferably, the heat-stabilized pigment is selected from the group consisting of: - Titanium redstone type yellow pigment - Bismuth derivative yellow pigments, such as those selected from stabilized bismuth vanadate (Py 184 ), - Red pigments, such as those selected from perylene red (e.g., PR149, PR178 and PR224), iron oxide, - Bismuth oxychloride type orange pigment (PO 85 ), - Bismuth vanadate orange pigment (PO) 86 ), - Zinc-tin-titanium orange pigment (PO) 82 ), - Cerium sulfide orange pigment (PO) 75 ; PO 78 ), - Chromium-antimony-titanium gold rutile orange-yellow pigment (PBr) 24 ), - Tin-zinc rutile orange-yellow pigment (Py 216 ), - Niobium oxide tin zinc sulfide orange-yellow pigment (Py 227 ), - Tin-niobium bioxide orange-yellow pigment, - Co3(PO4)2, - LiCoPO4, - CoAl2O4, - Cr2O3, - TiO2, Black pigment PBk28 (copper chromium black spinel). and its mixtures.

[0129] decorate According to one embodiment, the one or more layers (3b) are continuous and cover the entire layer (3a) (see Figure 1 ).

[0130] According to another embodiment, the one or more layers (3b) do not cover the entire layer (3a) and form at least one decoration (see Figure 2 ).

[0131] Advantageously, the one or more layers (3b) constitute a plurality of decorations, wherein one layer (i) contains one or more thermochromic pigments, and another layer (j) contains at least one temperature-referenced pigment composition (see Figure 3 ).

[0132] According to one implementation, the two decorations (i) and (j) are each presented as adjacent, non-overlapping patterns. For example, each decoration is represented by different geometric patterns uniformly distributed across the entire surface and alternating with each other (see...). Figure 4 A).

[0133] According to another implementation, the two decorations (i) and (j) partially overlap. For example, each decoration is represented by different geometric patterns that are uniformly distributed across the entire surface and partially overlap (see...). Figure 4 B).

[0134] Preferably, the two decorations (i) and (j) overlap, either because one decoration is a continuous layer and the other decoration covers it in a patterned form, or because the two decorations (i) and (j) are presented in an overlapping patterned form (see...). Figure 4 C).

[0135] Flash The glitter sheets suitable for use within the scope of this invention can be independently selected from mica glitter sheets with or without coating, silica glitter sheets with or without coating, aluminum glitter sheets with or without coating, and iron oxide glitter sheets with or without coating. Mica or silica glitter sheets coated with titanium dioxide may also be used. The glitter sheets suitable for use within the scope of this invention can be processed to produce specific color effects.

[0136] Advantageously, the flash sheet is selected from the group consisting of mica particles, aluminum particles, mica particles coated with titanium dioxide, or mixtures thereof.

[0137] Holographic flash Advantageously, the flash sheet is a holographic flash sheet, a mixture of magnetizable and non-magnetizable particles.

[0138] Magnetizable particles can advantageously be particles containing at least one ferromagnetic metal. These magnetizable particles can be homogeneous, i.e., composed of the same material, or composite, i.e., these magnetizable particles have a core-shell structure, wherein the ferromagnetic metal is located in the core and / or shell of the particle. As examples of composite magnetizable particles, mica glitter sheets coated with iron oxide (Fe2O3) or stainless steel fibers coated with a sol-gel material (as protection against corrosion during the coating process) can be specifically mentioned, or plastic glitter sheets coated with iron oxide (Fe2O3), or glitter sheets with a ferromagnetic metal core and a shell formed of plastic material or sol-gel material.

[0139] According to one embodiment, a portion of the magnetizable particles are oriented to form a three-dimensional decoration.

[0140] Advantageously, the mixture of magnetizable and nonmagnetizable particles accounts for 1% to 5% of the layer weight, preferably 2% to 3%.

[0141] Advantageously, the percentage of non-magnetizable particles in the mixture of magnetizable and non-magnetizable particles is 15% to 40% relative to the total weight of the mixture of magnetizable and non-magnetizable particles.

[0142] Advantageously, the D50 size of the magnetizable particles is less than or equal to 23 µm.

[0143] In this invention, the term "D50" refers to the maximum size present at 50% of the particle count.

[0144] Advantageously, the D90 size of the non-magnetizable particles is 20% to 250% of the D90 size of the magnetizable particles.

[0145] In this invention, the term "D90" refers to the maximum size present at 90% of the particle count.

[0146] Advantageously, the surfaces of magnetizable and / or non-magnetizable particles are colored.

[0147] Advantageously, the non-magnetizable particles are composed of mica, aluminum, or mica coated with titanium dioxide.

[0148] Advantageously, the magnetizable particles are composed of iron, iron oxide, iron-coated aluminum, or iron-coated mica, with the iron existing in the form of ferrite.

[0149] filler The filler in this invention can provide mechanical reinforcement and hydrophobicity, while improving the mechanical strength and thermal conductivity of the coating.

[0150] Fillers not only give color to coatings, but can also contribute to it.

[0151] Advantageously, the filler is selected from the group consisting of ceramic fillers (SiO2, etc.) and / or mineral fillers and / or metal fillers (Al2O3, SiO2, etc.) and / or silicon dioxide and / or diamond particles.

[0152] Preferably, the filler is selected from the group consisting of metal oxides, metal carbides, metal oxynitrides, metal nitrides and mixtures thereof.

[0153] Advantageously, the metal is a transition metal, such as at least one element selected from B, Ni, Ti, Zr or Hf.

[0154] More preferably, the packing material is selected from the group consisting of: - Reinforcing filler: organic or inorganic hard filler; inorganic hard filler is preferably silicon carbide, alumina, zirconium oxide or graphite, ceramics, carbonates, hydrated alumina, aluminum trioxide or one or more metal oxides, graphite, graphene particles. - Other reinforcing fillers are selected from metal oxides: silica, mica, layered fillers, clays such as montmorillonite, sepiolite, gypsum, kaolinite and lithium saponite, zinc oxide, quartz, zirconium phosphate, alumina, zirconium oxide, zinc oxide, copper oxide, and iron oxide. - Filler selected from reinforcing fibers: glass fiber, carbon fiber, or aramid fiber; - A conductive filler comprising transition metal carbides and / or transition metal nitrides: characterized in that the transition metal is at least one element selected from B, Ni, Ti, Zr, or Hf. For example: cubic boron nitride, diamond particles, metal particles; - Layered fillers that can impart lubricating properties, such as clay, graphene, or graphite.

[0155] More preferably, the filler is selected from the group consisting of alumina, silicon carbide, tungsten carbide, boron nitride, quartz, and mixtures thereof.

[0156] Some inorganic hard fillers, such as silicon carbide, not only have mechanical reinforcing properties, but also have the advantage of being conductive fillers, thus providing excellent thermal conductivity.

[0157] Adding this type of filler can improve cooking results by better transferring heat from the metal substrate to the food in contact with the coating.

[0158] Advantageously, the average diameter d50 of the packing is between 0.1 and 50 µm, and more advantageously between 5 and 15 µm.

[0159] Advantageously, when one layer of the coating (3) contains filler, the proportion of filler is 0.5 to 30% by weight, preferably 5 to 20% by weight, relative to the total dry weight of the layer after calcination.

[0160] Support components The properties of the support member (2) are suitable for use as heating elements in household appliances.

[0161] Those skilled in the art will know how to select appropriate support components based on the household appliance and its intended use.

[0162] For example, the support (2) is made of clay, glass, ceramic, pottery or metal substrate.

[0163] When the support (2) is a metal substrate, it is advantageously made of aluminum, stainless steel, cast iron or cast aluminum, iron, titanium or copper.

[0164] In this invention, aluminum refers to a metal composed of 100% aluminum or aluminum alloys.

[0165] Advantageously, when the support (2) is a metal substrate, it is aluminum, stainless steel or a multilayer metal substrate. The metal substrate (2) can be a two-layer or three-layer substrate, and these multilayer structures can be obtained, for example, by composite rolling, hot-press diffusion bonding (solid-state diffusion bonding) or hot or cold impact bonding.

[0166] Preferably, the metal substrate comprises alternating layers of metal and / or metal alloy.

[0167] According to one implementation, when the support member (2) is a metal substrate, it is an aluminum alloy, stainless steel or a multilayer metal substrate, and its surface (2a) is an aluminum alloy or stainless steel.

[0168] Preferably, when the support member (2) is a metal substrate, it is an aluminum substrate.

[0169] Advantageously, the thickness of the support (2) is between 0.5 mm and 10 mm.

[0170] Advantageously, the surface (2a) of the support (2) has been pre-treated to improve the adhesion of the coating to the substrate.

[0171] According to one embodiment, when the support (2) is a metal substrate, it has been surface treated, said surface treatment being chemical etching, brushing, hydration, sandblasting, shot peening, plasma or corona or laser-type physicochemical treatment, chemical activation or a combination of these different techniques.

[0172] Advantageously, the substrate surface (2a) to which the coating (3) of the present invention is to be applied can be treated to increase its specific surface area; for aluminum substrates, such treatment can be performed by adding materials through techniques such as anodizing (forming an alumina tubular structure), chemical etching, sandblasting, brushing, shot peening, or thermal spraying (flame, plasma, or arc spraying). Other metal substrates can also be treated by adding materials through techniques such as polishing, sandblasting, brushing, microbead shot peening, or thermal spraying (flame, plasma, or arc spraying).

[0173] As metal substrates that can be used in this invention, advantageous examples include anodized or non-anodized aluminum substrates, optionally polished, brushed, sandblasted, shot peened, or microbead peened; anodized or non-anodized aluminum alloy substrates, optionally polished, brushed, sandblasted, or microbead peened; steel substrates optionally polished, brushed, sandblasted, shot peened, or microbead peened; stainless steel substrates optionally polished, brushed, sandblasted, or microbead peened; cast steel, cast aluminum, or cast iron substrates; and copper substrates optionally hammered or polished.

[0174] Advantageously, when the support (2) is a metal substrate, it can be selected from a substrate composed of a ferritic stainless steel / aluminum / austenitic stainless steel layer, a substrate composed of a stainless steel / aluminum / copper / aluminum / austenitic stainless steel layer, a substrate of cast aluminum, aluminum or aluminum alloy pot body with a stainless steel outer bottom, or a metal composite rolled substrate, such as a double-layer composite rolled substrate comprising a layer of stainless steel (e.g. for constituting the inner surface of the appliance) and a layer of aluminum or aluminum alloy, anodized or unanodized (e.g. for constituting the outer surface of the appliance).

[0175] Advantageously, when the support (2) is a metal substrate, the arithmetic mean roughness Ra of the surface of the face (2a) of the support (2) is greater than or equal to 1 µm.

[0176] The arithmetic mean roughness Ra is measured using a roughness meter according to ISO 4287. Ra represents the arithmetic mean of the deviations relative to the mean. Surface topography can be studied, in particular, using a profilometer with a fine stylus (equipped with a diamond tip), or using an Altisurf® type optical metrology device, where a color confocal sensor allows for non-contact measurement. This study of surface topography can determine the arithmetic mean roughness Ra.

[0177] Advantageously, in the case of cooking appliances or electric cooking equipment, the support is a concave metal pot body, which includes a bottom and side walls rising from the bottom, the pot body having a concave inner surface adapted to receive food and a convex outer surface intended to face the heating device or heat source.

[0178] method The present invention also relates to a method for manufacturing a household appliance including a coated heating element, the household appliance including a coated support member, characterized by comprising the following steps: a) Provide a support member (2) in the form of a generally flat support member, which includes two opposing surfaces, or provide a support member (2) in the form of a convex or concave shape, which defines a concave inner surface (21) and a convex outer surface (22). a') When a support member (2) in the form of a generally flat support member is provided in step (a), optionally, the substrate is subjected to a shaping step to give it the shape of a support member (2) in the form of a convex or concave shape, which defines a concave inner surface (21) and a convex outer surface (22), said step (a') being performed before step (a), or before step (b) of applying the coating (3), or after step (b) and before step (c) of applying the top layer, or after step (c); b) Apply coating (3); c) Apply the sol-gel topcoat as described above to the coating (3).

[0179] Implementing this method can yield a household appliance whose support components are coated with a non-stick coating.

[0180] The support used in steps (a) and (a') is as described above.

[0181] Advantageously, the method according to the invention may further include a surface treatment step on the support surface to be coated prior to step a). This surface treatment may be a physicochemical treatment (particularly by plasma) or a chemical treatment (particularly chemical etching) and / or a mechanical treatment (e.g., sandblasting, brushing, grinding, shot peening) to produce a support surface roughness conducive to the adhesion of the undercoat. The surface treatment may also advantageously include a pre-treatment degreasing operation to clean the surface.

[0182] Advantageously, the support is optionally cleaned and heated before applying the composition according to step (b). The heating temperature can be between 40 and 80°C, and this preheating avoids sagging during application.

[0183] Advantageously, step (b) of the method according to the invention may include an intermediate drying step performed after the coating composition is applied and before the topcoat is applied.

[0184] The coating composition can be applied to the support by spraying or any other application method, such as dip coating, brush coating, roller coating, inkjet coating, curtain coating, centrifugal coating, or screen printing. However, spraying (e.g., using a spray gun) has the advantage of forming a uniform and continuous layer that, after firing, forms a continuous, uniform, and dense coating on a concave or convex substrate.

[0185] In step (b) of the method according to the invention, the application to the support can be performed by screen printing, roller coating, inkjet printing, spraying or curtain coating.

[0186] In the case of a sol-gel coating (3), application to the support in step (b) of the method according to the invention can be performed by spraying, including spraying or atomizing the sol-gel coating composition solution in the form of droplets. Application to the support in step (b) of the method according to the invention can also be performed by planar coating technology, which, from an industrial point of view, can significantly save coating consumption on the one hand and eliminate the problem of spraying on the outside of the appliance (“overspray”) on the other hand.

[0187] Advantageously, step (c) of the method according to the invention can be carried out at a temperature of 200 to 400°C, particularly at a temperature of 220 to 350°C, more particularly at a temperature of 250 to 320°C, preferably at 300°C.

[0188] A drying step can be considered between steps (b) and (c). Any drying method can be considered, such as oven drying, ultraviolet or infrared radiation drying, plasma drying, air drying, or a combination of these methods.

[0189] This optional drying step allows the solvent to evaporate and avoids stress associated with coating densification / firing.

[0190] After implementation of the method according to the invention, the total thickness of the coating can be between 1 and 200 µm, particularly between 2 and 100 µm, and preferably between 2 and 80 µm.

[0191] Home appliances The present invention also relates to a household appliance comprising a coated heating element (1) according to the invention or obtainable by the method described above.

[0192] According to one embodiment, the household appliance according to the invention is a cooking utensil (100) or an electric cooking device (200), and a sol-gel surface layer forms the cooking surface.

[0193] In this case, the surface layer according to the invention is advantageously transparent.

[0194] In this case, the colorant of the surface layer according to the invention is advantageously a glitter sheet.

[0195] The cooking utensil (100) is preferably a group consisting of a stew pot, a frying pan, a small pot or long-handled frying pan for cheese fondue or cheese gratin, a saucepan, a round-bottomed frying pan, a frying pan, a crepe pan, a grill, a flat baking pan, a deep pot, a casserole dish, a cookware liner or a bread machine liner, cooking molds, pastry molds and baking pans, a barbecue grill and a grill rack, and a cooking bowl.

[0196] According to one embodiment, the cooking appliance (100) includes a heating surface (6) for contact with an external heat source, which is opposite to a cooking surface (5) for contact with food during cooking.

[0197] The cooking utensil according to the invention can be in particular a cooking utensil in which one of the two opposing sides of the substrate is an inner surface, optionally concave, oriented toward food that may be introduced into or onto the utensil, while the other side of the substrate is an outer surface, optionally convex, oriented toward a heat source.

[0198] The electric cooking equipment (200) is preferably selected from the group consisting of an electric crepe pan, an electric cheese grill, an electric cheese fondue, an electric grill, an electric flat griddle, an electric cooker, a bread maker, a pressure electric cooking equipment, a waffle maker, a rice cooker, and a jam pot.

[0199] The electric cooking appliance (200) includes a coated heating element (1) according to the invention and a heat source (210) configured to heat the coated heating element (1).

[0200] According to one embodiment, the household appliance according to the invention is a heating household device in the field of clothing care or personal care.

[0201] Advantageously, the household appliance according to the invention is an iron, and the soleplate of the iron is coated with a sol-gel coating; or a hair care appliance, and one of the heating plates of the appliance is coated with a sol-gel coating.

[0202] Example The objects, aspects and advantages of the invention will be better understood through the following description of specific embodiments of the invention, which are given by way of non-limiting example.

[0203] Of course, the present invention is by no means limited to the embodiments described and illustrated, which are given by way of example only. Modifications can be made without departing from the scope of protection of the present invention, particularly from the perspective of the composition of various elements or by substitution with technical equivalents.

[0204] Starting layer formulation Topcoat = Surface layer Base formula Boiling water test To simulate the aging process caused by water-based cooking, we conducted a boiling water aging test.

[0205] The testing process is as follows: - Clean the frying pan with warm water, a yellow sponge, and detergent before testing; - Fill with tap water and heat to a boil; - When boiling is reached, keep heating and start the timer; - After boiling for 2 hours: Clean the appliance with warm water, a yellow sponge, and detergent to remove surface scale.

[0206] - Assess non-stickiness by frying an egg.

[0207] - If the egg falls off, clean it and start a new boiling cycle.

[0208] Repeat this boiling cycle as many times as necessary until the eggs no longer fall off.

[0209] The higher the number of cycles (i.e., hours), the more resistant the coating is to boiling water.

[0210] Comparison results To further improve non-stickiness and hydrophobicity, TMMS (trimethylmethoxysilane) was used to replace part of MTMS in the above starting formulation.

[0211] Multiple prototypes were prepared, incorporating variations in the TMMS / MTMS ratio and PDMS oil content in the topcoat. The undercoat was identical for all prototypes, as described above. The coating consisted of an undercoat and a topcoat layer varying according to the prototype. The topcoat varied in the MTMS / TMMS ratio. The topcoat also varied in the PDMS oil content (in the above topcoat formulations, the solvent amounts of isopropanol and butyl ethylene glycol were adjusted based on the PDMS oil content to achieve a total of 100).

[0212] The table below summarizes the tests conducted and the non-stick durability results obtained through the above-mentioned cyclic boiling test.

[0213] The proportion of precursors is given as a proportion relative to the total amount of precursors.

[0214] Complete data / all configurations: The MTMS / TMMS formulation achieved excellent performance.

Claims

1. Use of a sol-gel surface layer for imparting non-stick properties or improving the non-stick durability of a fluorocarbon-free coating (3), said coating (3) being applied to at least one surface (2a) of a support (2) for a heating element of a household appliance, characterized in that, The surface layer is silica-free and is obtained from a sol-gel composition containing at least two polyalkoxysilane precursors. - The first precursor is selected from the group of formula (I). R x Si(OR’) 4-x (I) in R is (C1-C6)-alkyl, (C2-C6)-alkenyl, (C3-C7)-cycloalkyl, (C4-C7)-cycloalkenyl, (C3-C7)-cycloalkyl-(C1-C6)-alkyl, aryl, or aryl-(C1-C6)alkyl, optionally substituted; R' is (C1-C8)-alkyl; and x is 0, 1, 2 or 3; and - The second precursor is TMMS (trimethylmethoxysilane) or TMES (trimethylethoxysilane) or a mixture thereof.

2. The use of the sol-gel surface layer according to claim 1, characterized in that, The ratio between the first precursor and the second precursor is between 1:10 and 10:1, preferably between 5:1 and 1:

5.

3. The use of the sol-gel surface layer according to claim 1 or 2, wherein the first precursor is methyltrimethoxysilane (MTMS) or methyltriethoxysilane (MTES) or a mixture thereof.

4. The use of the sol-gel surface layer according to claim 3, characterized in that, The first precursor is MTMS and the second precursor is TMMS.

5. The use of the sol-gel surface layer according to any one of the preceding claims, characterized in that, It also contains at least one functionalized or nonfunctionalized, reactive or nonreactive silicone oil.

6. A method for manufacturing a coated heating element (1) for use in a household appliance including a coated support (2), the method comprising the following steps: a) Provide a support member (2) having at least one surface to be coated (2a); b) Apply a coating (3) to at least one surface (2a) of the support member to be coated; c) Apply a sol-gel topcoat according to any one of claims 1 to 5 to the coating (3).

7. The method according to claim 6, characterized in that, In step c), the sol-gel coating is applied by electrostatic powder spraying, spraying, screen printing, spray gun, doctor blade, coating roller, brush, roller coating or digital printing, preferably by spraying.

8. A coated heating element (1) for a household appliance, which can be obtained by the method according to any one of claims 6 to 7.

9. A method for manufacturing a household appliance, the household appliance comprising a coated heating element (1) for a household appliance according to claim 8, the household appliance comprising a coated support member (2), characterized in that, The method includes the following steps: a) Provide a support member (2) in the form of a substantially flat support member, the flat support member comprising two opposing surfaces, or provide a support member (2) in the form of a convex or concave shape, the convex or concave shape defining a concave inner surface (21) and a convex outer surface (22). a') When a support member (2) in the form of a substantially flat support member is provided in step (a), optionally, the substrate is subjected to a shaping step to give it the shape of a support member (2) in the form of a convex or concave shape, the convex or concave shape defining a concave inner surface (21) and a convex outer surface (22), the step (a') being performed before step (a), or before step (b) of applying the coating (3), or after step (b) and before step (c) of applying the topcoat, or after step (c); b) Apply coating (3); c) Apply a sol-gel topcoat according to any one of claims 1 to 5 to the coating (3).

10. A household appliance comprising a coated heating element (1) according to claim 8 or a coated heating element (1) obtainable by the method according to claim 9.

11. The household appliance according to claim 10, characterized in that, It is a cooking utensil or electric cooking device, and the sol-gel surface layer forms the cooking surface.

12. The cooking utensil (100) according to claim 11, selected from the group consisting of a stew pot, a frying pan, a small pot or long-handled skillet for cheese fondue or cheese gratin, a saucepan, a round-bottomed frying pan, a frying pan, a crepe pan, a grill, a flat baking pan, a deep pot, a casserole dish, a cookware liner or a bread machine liner, a cooking mold, a pastry mold and a baking pan, a grill rack and a grill wire rack, and a cooking bowl.

13. The electric cooking appliance (200) according to claim 11 is selected from the group consisting of an electric crepe pan, an electric cheese grill, an electric cheese fondue, an electric grill, an electric flat griddle, an electric cooker, a bread maker, a pressure electric cooking appliance, a waffle maker, a rice cooker, and a jam pot.

14. The household appliance according to claim 10, characterized in that, It is a heated household appliance in the field of clothing care or personal care.

15. The household appliance according to claim 14, characterized in that, It is an iron and the sol-gel coating is applied to the soleplate of the iron, or it is a hair care device and the sol-gel coating is applied to the heating plate of the device.

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