Non-fluorinated hybrid enamel / silicone resin coating

Abstract

The present invention relates to a coated cooking element (1) for a cookware or electric cooktop, comprising a metal substrate (2) coated on at least one side (2a) with at least the following layers, starting from the metal substrate (2) in this order: (3a) an enamel base layer, (3b) one or more optional intermediate layers consisting of one or more colorants and, optionally, one or more silicone resins, one or more thermoplastic polymers, one or more fillers, and / or one or more additives, and (3c) a finish layer intended for contact with food, consisting of one or more silicone resins and, optionally, one or more thermoplastic polymers, one or more fillers, one or more additives, and / or flakes. The present invention also relates to a method for producing said cooking element.

Description

[Technical Field]

[0001] The field of the invention is that of cookware coated with a coating on one of their surfaces, more precisely that of cookware coated with a silicone resin-based coating on these items.

[0002] In the cookware field, fluoropolymer-based coatings, particularly polytetrafluoroethylene (PTFE), are commonly known for their anti-stick and heat-resistant properties.

[0003] However, these coatings have low mechanical strength.

[0004] Patent document 1 (WO 2020 / 144051) relates to a fluoropolymer-based coating, the mechanical resistance to abrasion of which is improved by incorporating organic (SiC) and mineral (Al2O3) fillers in the primary and finishing layers of the coating.

[0005] The performance improvements achieved in terms of mechanical strength are satisfactory, but still not optimal.

[0006] In order to improve the resistance of such coatings to mechanical impacts, coatings having a hard base layer coated with an anti-adhesion coating have been described, inter alia, in WO 2009 / 068832.

[0007] Fluoropolymer-based coatings are primarily intended for pots and pans, but other applications are possible due to their stampability in the field of molding (molds, cake pans, waffle makers, etc.) or small household appliances (rice cookers, fryer containers, electric crepe makers).

[0008] An alternative to PTFE coatings consists of the use of so-called "ceramic" coatings, developed by the sol-gel method and the use of tetraethyl orthosilicate (EP 2806776). These coatings have the particular property of being hard and resistant to mechanical wear, but also exhibit brittle behavior and poor non-adhesion compared to fluoropolymer-based coatings.

[0009] Furthermore, these coatings lack punchability and are therefore less suitable for molding and small domestic appliances.

[0010] In the field of molding (civil or industrial), fluoropolymer-based coatings are less prevalent because of the lower thermal resistance constraints (up to 220 °C), which allows the use of other types of coatings, such as silicone coatings.

[0011] Pure silicone resins are described as non-stick and resistant to temperatures above 220-230°C. On the other hand, they are considered to adhere poorly to substrates.

[0012] Silicone polyester resins, on the other hand, are widely used in molding because they adhere to substrates, are suitable for punching, and are non-stick. However, they decompose at temperatures above 230°C. More specifically, cookware is used in the temperature range of 50-250°C, and for products with induction bottoms, it is not surprising that temperatures of 300°C or even 350°C can be reached. Therefore, their use is incompatible with the operating temperatures in the cookware field.

[0013] However, control of the cooking temperature is an essential parameter, as it determines the success of the cooking and ensures the preservation of the physicochemical properties of the anti-stick coating.

[0014] With this in mind, consumer cooking start temperature indicators have been developed to indicate, by a color change, the temperature at which the consumer can start cooking their food, thus avoiding the possibility of overheating the food.

[0015] This technology generally relies on the use of thermochromic pigments, which change color between ambient temperature and 250°C depending on the properties of the material.

[0016] In addition to thermochromic pigments, other visual differentiating elements can be added to the coating (EP 2675328 A1, EP 2412846 A1).

[0017] Patent document 6 (EP 2319631) describes the development of a two-layer silicone resin-based coating combined with 0.5-20% high-temperature thermoplastic material (base layer), resulting in a mechanically strong, adherent, and non-adhesive coating. The nature of the thermoplastic resin varies between the base layer (PEEK) and the finish layer (PPS), with the thermoplastic resin being primarily located in the base layer to ensure adhesion to the substrate. This patent does not describe a temperature indicator.

[0018] US Patent Application Publication No. 2022 / 0073785 proposes a two-layer silicone / thermoplastic coating architecture that is much more concentrated in thermoplastic materials and does not describe the incorporation of a colored indicator based on thermochromic pigments. [Prior art documents] [Patent documents]

[0019] [Patent Document 1] International Publication No. 2020 / 144051 [Patent Document 2] International Publication No. 2009 / 068832 [Patent Document 3] European Patent No. 2806776 [Patent Document 4] European Patent Application Publication No. 2675328 [Patent Document 5] European Patent No. 2412846 [Patent Document 6] European Patent No. 2319631 [Patent Document 7] US Patent Application Publication No. 2022 / 0073785 Summary of the Invention [Problem to be solved by the invention]

[0020] Therefore, improved cooking utensils are needed, in particular those that allow better control, especially visual control, of the cooking of food while ensuring good mechanical strength, good heat resistance, simple and flexible implementation (e.g., in terms of the variety of reagents that can be used) at reasonable industrial costs. [Means for solving the problem]

[0021] A first object of the present invention relates to a coated cooking element (1) for a cooking utensil or electric cooking appliance, comprising a metal substrate (2) coated on at least one side (2a) with at least the following layers, starting from the metal substrate (2) and in this order: (3a) A base layer comprising or consisting of a rough enamel layer containing less than 50 ppm of lead and less than 50 ppm of cadmium, having the following characteristics: - a hardness higher than the hardness of the metal substrate constituting the support (2), a melting point between the melting point of the metal substrate constituting the support (2) and the melting point of one or more components of the intermediate layer (3b) and the finishing layer (3c), and Surface roughness Ra of -2 to 50 μm, a base layer having (3b) one or more optional intermediate layers containing one or more colorants and, optionally, one or more silicone resins, and / or one or more thermoplastic polymers, and / or one or more fillers, and / or - one or more additives one or more intermediate layers, (3c) A finish layer intended to come into contact with food during cooking, comprising one or more silicone resins and, optionally, one or more thermoplastic polymers, and / or one or more fillers, and / or one or more additives, and / or -flake A finishing layer consisting of

[0022] Another object of the invention relates to a method for manufacturing the coated cooking element according to the invention, comprising the following successive steps: i. providing a metal substrate comprising at least one surface intended to be coated; ii. optionally, pretreating the surface (2a) of the metal substrate intended to be coated; iii. applying an enamel base layer; iv. curing the layer applied in step (iii) to obtain a base layer (3a); v. Optionally, applying at least one intermediate layer (3b); vi. Optionally, drying the one or more intermediate layers (3b); vii. applying at least one finishing layer (3c); viii. Curing all base layers (3a), intermediate layers (3b) and finish layers (3c).

[0023] Another object of the present invention relates to a cooking utensil comprising a coated cooking element according to the invention.

[0024] Another object of the invention relates to an electric cooking appliance comprising a coated cooking element and a heating source configured to heat said coated cooking element, characterized in that said coated cooking element is according to the invention.

[0025] The present invention has at least one of the following advantages. - The coating according to the invention as thermochromic functional, with outstanding visibility, contrast across a targeted temperature range, and a color change centered around food cooking temperatures, for example for kitchenware. The coating according to the invention is able to provide good temperature control when cooking food, which is necessary not only for health and taste reasons but also for safety and to limit occasional overheating which would weaken the coating. The thermochromic pigment composition has reversible thermochromic properties, i.e., when the temperature is reduced, after the color change under the action of heat, the compound returns to its initial state and its initial color, and this color change cycle (reversibility) can be repeated indefinitely. The coating according to the invention has a remarkable thermal stability at elevated temperatures, being stable up to about 450°C. The coating according to the invention has a high mechanical resistance, especially against impacts. The coating according to the invention has good chemical stability, especially towards aggressive detergents.

[0026] definition The term "layer" in the context of the present invention should be understood as a continuous layer or a discontinuous layer. A continuous layer (also called a monolithic layer) is a single whole that forms an entire plane that completely covers the surface to which it is applied. A discontinuous layer (or non-monolithic layer) can include multiple parts and is therefore not a single whole.

[0027] The terms "base layer", "primer layer", "adhesion layer" or "adhesion primer" are intended to mean all layers from the first layer applied directly to the substrate (which preferably adheres well to the substrate and contributes all its mechanical properties (hardness, scratch resistance) to the coating) to the last layer before the first decorative layer.

[0028] The term "finishing layer" or "finish" is intended to mean a continuous, transparent surface layer which protects the decorative layer from mechanical attack and provides the coating with anti-adhesive properties while allowing full visibility of the decorative layer. Preferably, the finishing layer is intended to come into contact with food.

[0029] The term "decoration" or "decorative layer" shall mean one or more continuous or discontinuous layers containing a pigment composition. The decoration may be in the form of one or more patterns having one or more colors. The decoration is clearly visible to the user with the naked eye and at distances conventional for use of household items.

[0030] The term "overlapping layer" is intended to mean partially or completely overlapping layers. These layers may be in the form of overlapping patterns, for example, concentric disks.

[0031] The term "adjacent layers" is intended to mean layers that are not superimposed. These layers may be in the form of the same or different patterns that are not superimposed, and are preferably uniformly distributed.

[0032] The term "reference temperature pigment composition" is intended to mean a composition containing a pigment that, at a given temperature, can indicate to a user that the temperature of optimum use has been reached. This indication is made by comparing the color of the thermochromic pigment composition with the color of the reference temperature pigment composition. The temperature of optimum use is reached either when the colors are identical, or when the colors are visually very different.

[0033] A "reference temperature pigment composition" can include a pigment having: - At the temperature of optimum use, the same color as the thermochromic pigment composition, *This pigment, at ambient temperature, has the same color as the thermochromic pigment composition at the temperature of optimum use and does not change color with temperature. * Or, because at ambient temperature the pigment has a different color than the thermochromic pigment composition that changes to the same color as the thermochromic pigment composition at the temperature of optimum use; -Whether this pigment changes color with changes in temperature, or not, a color very different from thermochromic pigment compositions at the optimum temperature of use.

[0034] The optimum temperature of use can be reached when the color of the reference temperature pigment composition corresponds to the color indicated in the user guide for the household product containing the coating of the present invention or to the color indicated on the color scale supplied to the user together with said article.

[0035] The reference temperature pigment composition may be, for example, a reference cooking temperature pigment composition or may be intended to indicate the risk of overheating. The reference temperature pigment composition may be thermochromic or thermostable.

[0036] The term "thermochromic semiconductor" in the sense of the present invention is intended to include mineral or organic compounds that undergo a reversible color change upon increasing temperature. The gradual and reversible thermochromism of these semiconductor compounds is associated with the decrease in the width of the semiconductor's band gap due to the expansion of the material. More specifically, the periodicity of the anion and cation network leads to the concentration of energy levels into energy bands. The high-energy filled energy band is called the valence band, and the low-energy empty energy band is called the conduction band. Between these two bands lies a forbidden band, called the band gap. The color of a semiconductor material can result from the presence of a charge transfer (interatomic photon absorption) corresponding to the passage of electrons from the valence band to the conduction band on a given atom, or generally from an anion orbital to a cation orbital.

[0037] In the field intended for the present invention, optimum conditions are achieved when the coating reaches a temperature suitable for cooking food, preferably between 100 and 250°C.

[0038] In the context of the present invention, the term "thermochromic pigment or pigment composition" should be understood to mean a pigment or pigment composition that changes color as a function of temperature in a given temperature range, this change being reversible. This color change is visible to the user with the naked eye at conventional use distances.

[0039] The term "thermally stable pigment" shall mean a pigment that does not exhibit a change in color when exposed to an elevated temperature within a given temperature range, or a pigment that exhibits a change in hue when exposed to an elevated temperature within a given temperature range that is so small that it is not visible to the user with the naked eye and is not visible at conventional use distances.

[0040] The heat stable pigment preferably has a color change ΔE between 25°C and 200°C. * is less than 10, and ΔE* is defined by the CIE 1976 formula in the CIELAB color space.

[0041]

number

[0042] L1 * , a1 * and b1 * is the L of the compound at ambient temperature * a * b * characterize the values, L2 * , a2 * and b2 * is the L of the compound at 200 °C * a * b * Characterize the value.

[0043] The expression "identical in color" shall mean indistinguishable by the user with the naked eye at conventional use distances.

[0044] The term "silicone resin-based coating" is intended to mean a coating that includes one or more silicone resins in one or more of its layers.

[0045] In the context of the present invention, "enamel layer" is intended to mean a continuous or discontinuous layer comprising enamel.

[0046] In the context of the present invention, the term "surface dispersion of enamel droplets" is intended to mean a discontinuous enamel layer having divisions on the substrate (in this case the cookware) such that the dispersed enamel droplets create roughness in this layer.

[0047] In the context of the present invention, the term "substrate coverage" is intended to mean the proportion of the area of the substrate that is effectively covered by the surface distribution of enamel droplets, divided by the total area of the substrate that can be covered by the base layer, expressed as a percentage. The terms "substrate" or "substrate" are used interchangeably and designate the same object.

[0048] In the context of the present invention, the term "surface roughness Ra" means the arithmetic mean deviation between the peaks and valleys of a surface relative to a median (or mean) line, this deviation being estimated according to standard ISO 4287. The arithmetic mean roughness Ra is measured by a profilometer according to standard ISO 4287. The surface topography can be studied in particular using a profilometer equipped with a probe equipped with a fine stylus with a diamond tip, or by optical measuring instruments of the Altisurf® type, in which a confocal chromaticity sensor allows for contactless measurements. The study of this surface topography data makes it possible to define the arithmetic mean roughness Ra.

[0049] In the context of the present invention, the term "d50" is intended to mean the maximum size exhibited by 50% of the particles by number.

[0050] In the context of the present invention, the term "d90" is intended to mean the maximum size exhibited by 90% of the particles by number.

[0051] The expression "cookware" is to be understood in the context of the present invention as an article for cooking food, which for this purpose is intended to be subjected to a heat treatment. The cookware therefore comprises an "inner surface" or "cooking surface", the coating of which is intended to come into contact with food during cooking.

[0052] The expression "article intended to undergo a heat treatment" is to be understood in the context of the present invention as an article that can be heated by an external heating system, such as a frying pan, a saucepan, a sauté pan, a wok, a barbecue grill, etc., and that is capable of transferring the heat provided by this external heating system to a material or food that comes into contact with said article.

[0053] The expression "electric cooking appliance" is to be understood in the context of the present invention as 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 plancha grill, an electric cooker, a bread machine or an electric pressure cooker.

[0054] In the present invention, the weight percentages are expressed as dry weights, i.e. without solvent.

[0055] The term "coating" is intended to mean any layer that covers and adheres to a metal substrate. The coating obtained by the present invention is advantageously solid. The term "solid" refers to the property of the adhesive material to be insoluble in water, common solvents, food ingredients such as aqueous or fatty mixtures, even though the material may have high hardness or high flexibility, such as an elastomer. [Brief explanation of the drawings]

[0056] [Figure 1]FIG. 1 is a diagram of a cooking element according to the invention, in which layer (3b) is continuous and completely covers layer (3a). [Figure 2] FIG. 10 is a view of a cooking element according to the invention, in which layer (3b) does not entirely cover layer (3a) but forms a decoration. [Figure 3] FIG. 1 is a diagram of a cooking element according to the invention, in which layer (3b) consists of two decorations (i) and (j). [Figure 4] Pattern distribution diagrams. 4A is a non-overlapping adjacent pattern. 4B is a partially overlapping pattern. 4C is an overlapping pattern. [Figure 5] 1 is a diagram of a cooking appliance according to the present invention; [Figure 6] 1 is a diagram of an electric cooking appliance according to the present invention; DETAILED DESCRIPTION OF THE INVENTION

[0057] The present invention relates to a coated cooking element (1) for a cooking utensil or electric cooking appliance, comprising a metal substrate (2) coated on at least one side (2a) with at least the following layers, starting from the metal substrate (2) and in this order: (3a) A base layer comprising or consisting of a rough enamel layer containing less than 50 ppm of lead and less than 50 ppm of cadmium, - a hardness higher than the hardness of the metal substrate constituting the support (2), a melting point between the melting point of the metal substrate constituting the support (2) and the melting point of one or more components of the intermediate layer (3b) and the finishing layer (3c), and Surface roughness Ra of -2 to 50 μm A base having the characteristics of (3b) one or more optional intermediate layers containing one or more colorants and, optionally, one or more silicone resins, and / or one or more thermoplastic polymers, and / or one or more fillers, and / or - one or more additives one or more intermediate layers, (3c) A finish layer, typically intended to come into contact with the food product during cooking, comprising one or more silicone resins and, optionally, one or more thermoplastic polymers, and / or one or more fillers, and / or one or more additives, and / or -flake A finishing layer consisting of

[0058] Advantageously, the layers (3a) and optionally (3b) and (3c) form a coating (3) that coats the metal substrate (2), said coating (3) having anti-adhesion properties and forming an anti-adhesion coating.

[0059] Advantageously, the layer (3a) is in contact with the metal substrate (2) through one of its faces, via its face (2a).

[0060] At least one coated surface (2a) of the metal substrate is therefore the cooking surface, in other words the coating of the cooking element (1) according to the invention is intended to come into contact with food.

[0061] The coating of the cooking element (1) according to the invention is intended to come into contact with food.

[0062] Advantageously, the top layer (3c) is in contact with the food product through one of its faces, thus forming the cooking surface (5).

[0063] The coating of the cooking element (1) according to the invention does not contain a fluorinated polymer, also called a fluoropolymer, in other words, said coating is a fluorinated polymer or is devoid of a fluorinated polymer.

[0064] Advantageously, the thickness of the layer (3a) is 10 μm to 100 μm, preferably 20 μm to 85 μm, particularly preferably 30 μm to 70 μm. If the base layer (3a) is discontinuous, its thickness is preferably 10 μm to 50 μm. If the base layer (3a) is continuous, its thickness is preferably 50 μm to 100 μm.

[0065] Advantageously, the thickness of the layer (3b) is between 1 μm and 100 μm, preferably between 2 μm and 30 μm, particularly preferably between 3 μm and 10 μm.

[0066] Advantageously, the thickness of the layer (3c) is between 0.05 μm and 100 μm, preferably between 0.08 μm and 20 μm, particularly preferably between 0.1 μm and 10 μm.

[0067] According to one embodiment, the thickness of the layer (3c) is comprised between 0.1 μm and 2 microns (2 μm), preferably between 0.2 μm and 1.5 μm.

[0068] According to another embodiment, the thickness of the layer (3c) is between 10 μm and 100 μm, preferably between 20 μm and 85 μm, particularly preferably between 30 μm and 70 μm.

[0069] According to a particular embodiment, The thickness of the layer (3a) is 10 μm to 100 μm, typically 20 μm to 85 μm, The thickness of the layer (3b) is 1 μm to 100 μm, preferably 2 μm to 30 μm, The thickness of the layer (3c) is 0.05 μm to 100 μm, preferably 0.08 μm to 20 μm.

[0070] The coating of the cooking element (1) according to the invention may comprise one or more optional layers (3ab), interposed between one or more layers (3a) and one or more layers (3b) or between one or more layers (3a) and one or more layers (3c), comprising one or more silicone resins and, optionally, one or more thermoplastic polymers, and / or one or more fillers, and / or -One or more additives. It consists of:

[0071] Advantageously, the thickness of the layer(s) (3ab) is between 0.05 μm and 100 μm, preferably between 0.08 μm and 20 μm, particularly preferably between 0.1 μm and 10 μm.

[0072] metal base material Advantageously, said metal substrate (2), also called support, is a substrate made of aluminum, stainless steel, cast iron or cast aluminum, iron, titanium or copper.

[0073] In the sense of the present invention, aluminum is to be understood as a metal consisting of 100% aluminum or an aluminum alloy.

[0074] Advantageously, the metal substrate (2) is a substrate made of aluminum, stainless steel or a multilayer metal substrate. The metal substrate (2) may also be a two-layer or three-layer substrate, these multiple layers being obtained, for example, by co-lamination, solid-state bonding or hot or cold impact bonding.

[0075] Preferably, the metal substrate (2) comprises alternating layers of metals and / or metal alloys.

[0076] According to one embodiment, the metal substrate (2) is a substrate made of an aluminum or stainless steel alloy or a multilayer metal substrate whose face (2a) is an aluminum or stainless steel alloy.

[0077] Preferably, the metal substrate (2) is an aluminum substrate.

[0078] Advantageously, the thickness of the metal substrate (2) is between 0.5 mm and 10 mm.

[0079] Advantageously, the face (2a) of the metal substrate (2) has undergone a prior surface treatment to improve the adhesion of the coating to said substrate.

[0080] According to one embodiment, the surface of face (2a) of the metal substrate (2) has undergone a surface treatment, said surface treatment being chemical etching, brushing, hydration, sandblasting, shot peening, physicochemical plasma, corona or laser treatment, chemical activation or a combination of these different techniques.

[0081] Advantageously, the surface (2a) of the substrate to which the coating (3) according to the invention is applied can be treated to increase its specific surface area; in the case of aluminum substrates, this treatment can be carried out by anodizing (creating a tubular alumina structure), chemical etching, sandblasting, brushing, shot peening, or the addition of materials using techniques such as thermal spraying (flame, plasma, or arc spraying). Other metal substrates can also be polished, sandblasted, brushed, microbead blasted, or subjected to the addition of materials using techniques such as thermal spraying (flame, plasma, or arc spraying).

[0082] Metals that can be used as substrates in the present invention advantageously include substrates made of aluminum, which may or may not be anodized, and optionally polished, brushed, sandblasted, shot-peened, or microbead-blasted; substrates made of aluminum alloys, which may or may not be anodized, and optionally polished, brushed, sandblasted, or microbead-blasted; substrates made of steel, which may or may not be anodized, and optionally polished, brushed, sandblasted, shot-peened, or microbead-blasted; substrates made of stainless steel, which may or may not be polished, brushed, sandblasted, or microbead-blasted; substrates made of cast steel, aluminum, or iron; and substrates made of copper, which may or may not be hammered or polished.

[0083] Advantageously, the substrate may be chosen from substrates comprising layers of ferritic stainless steel / aluminum / austenitic stainless steel, substrates comprising layers of stainless steel / aluminum / copper / aluminum / austenitic stainless steel, cast aluminum lined with a stainless steel outer bottom, aluminum or aluminum alloy calotte, metal co-laminate substrates, for example two-layer co-laminate substrates comprising a stainless steel layer (e.g., intended to constitute the inner surface of the article) and an anodized or non-anodized aluminum or aluminum alloy layer (e.g., intended to constitute the outer surface of the item).

[0084] Advantageously, the arithmetic mean roughness Ra of the surface of face (2a) of the metal substrate (2) is 1 μm or more. The arithmetic mean roughness Ra is measured by a profilometer according to standard ISO 4287. Ra represents the arithmetic mean of deviations from the mean. The surface topography can be studied, in particular, using a profilometer equipped with a probe equipped with a fine stylus with a diamond tip, or by optical measuring instruments of the Altisurf® type, in which a confocal chromaticity sensor allows for contactless measurements. Study of this surface topography data makes it possible to define the arithmetic mean roughness Ra.

[0085] enamel Preferably, the melting point of the base layer (3a) is between a temperature Tf1 that is 50°C higher than the highest melting point of the components of the intermediate layer (3b) and the finishing layer (3c) and a temperature Tf2 that is 10°C lower than the melting point of the metal substrate that constitutes the support (2).

[0086] Therefore, the base enamel layer does not contain silicone resin.

[0087] It is recognized that such a base layer disposed between the substrate and the anti-adhesion coating provides significant improvements in the physical, chemical, and mechanical performance of the anti-adhesion coating.

[0088] Thus, abrasion resistance is typically at least tripled compared to the same anti-stick coating without the hard enamel base layer, while maintaining its anti-stick properties.

[0089] According to a first embodiment, the hard base layer is a discontinuous layer comprising a surface dispersion of enamel droplets uniformly distributed on the inner surface of the article, with a coverage of the inner surface between 40% and 80% and a density per unit area of 300 droplets / mm 2 ~2000 drops / mm 2 and the droplet size is 2 μm to 50 μm.

[0090] According to a second embodiment, the hard base is a continuous enamel layer completely covering said inner surface of the support and having a thickness of at least 50 μm. In this second embodiment, such a continuous hard base creates a corrosion barrier against chemical attack by foodstuffs that protects the metal support, especially when this is an aluminum support, thereby improving its resistance to corrosion.

[0091] According to a first embodiment example, the hard base layer (3a) is a discontinuous enamel layer comprising a surface dispersion of solidified enamel droplets, having an average size of 2 μm to 50 μm, uniformly distributed on the surface of the face (2a), with a degree of coating of the inner surface of 40 to 80% and a density per unit area of 300 droplets / mm 2 ~2000 drops / mm 2 is.

[0092] According to this first example, enamel droplets dispersed on the surface of the inner surface (2a) are embedded in the intermediate layer (3b) and optionally the finishing layer (3c), allowing the fixation of said layers to the hard enamel base layer (3a). Such a hard base layer (3a) enameled in the form of a surface dispersion of enamel droplets provides increased mechanical reinforcement of the anti-adhesive coating, particularly in terms of hardness and adhesion to the substrate (2).

[0093] Preferably, the base layer (3a) according to the first embodiment has a surface roughness Ra of 2 μm to 15 μm, more preferably 8 μm to 15 μm.

[0094] A roughness of more than 15 μm has the consequence that the anti-adhesion coating (ie the combination of layers 3a+3b+3c) is no longer smooth.

[0095] In a variation of the second embodiment, the base layer (3a) is a continuous enamel layer (100% coverage) that completely covers the surface (2a) of the support (2) and has a thickness of 50 μm to 100 μm. Given that the base layer (3a) is continuous in this second embodiment, the surface roughness is not generated by the dispersion of solidified enamel droplets on the surface, as in the first embodiment, but by depressions and protrusions formed on the surface of the base layer (3a) due to the presence of insoluble fillers in the enamel composition of the base layer (3a). Such a base layer (3a) advantageously has a surface roughness Ra of 2 to 8 μm.

[0096] A surface roughness Ra of 2 to 8 μm provides good adhesion of the intermediate layer (3b) and the finishing layer (3c) to the base layer (3a), resulting in high wear resistance without compromising the anti-adhesion properties.

[0097] This is no longer the case for surface roughnesses Ra below 2 μm: the adhesion of the anti-adhesion coating to the base layer becomes too weak. Also, for surface roughnesses Ra above 8 μm, the abrasion resistance and anti-adhesion properties of the coating become weak.

[0098] Indeed, given that the combination of intermediate layer (3b) and finishing layer (3c) generally has a thickness on the order of 15 μm to 45 μm, any bumps created by the solidified enamel droplets are unlikely to be smoothed out by the combination of intermediate layer (3b) and finishing layer (3c).

[0099] Silicone resin In the present text, the term "silicone resin" is used interchangeably to refer to silicone before or after its crosslinking.In the present text, the term "silicone" refers to organopolysiloxane material.Crosslinking is a process that allows silicone to be converted into an insoluble material, for example, by polyaddition, polycondensation, or dehydrogenation.Crosslinking is carried out on precursors, which are generally silicone oils or resins, which crosslink to obtain a three-dimensional network that forms the material referred to herein as silicone resin.

[0100] This crosslinking can be achieved by thermal activation or chemical activation using a catalyst such as platinum.

[0101] Silicone resins can be obtained from precursors, such as crosslinkable oils or resins, which are advantageously soluble in solvents or emulsions in water, and which are in particular selected from silicone hydrides, silicone oil resins containing at least one vinyl group (-CH=CH2), silicone resins or silicone-polyester resins (copolymers) containing at least one alkoxy group, for example, methoxy or ethoxy group, and / or silicone resins or silicone-polyester resins (copolymers) containing at least one alkoxy group, in particular, ethoxy or hydroxy group, and mixtures thereof. These precursors have the ability to crosslink to obtain silicone resins, which are characterized by their insolubility and substantially solid form.

[0102] Advantageously, these precursors are polymers or oligomers, either in the form of silicone oils with various degrees of branching, or silicone resins with various degrees of pre-crosslinking, or silicone resin copolymers such as silicone-polyester, silicone-alkyd, silicone-polyurethane, or silicone-epoxy resins, or in the form of mixtures of silicone oils, silicone resins, and silicone resin copolymers. The silicone 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) hydroxy or alkoxy (especially methoxy, ethoxy, butoxy) functional groups as substituents of the silicone atoms.

[0103] Advantageously, the one or more silicone resins obtained after crosslinking, i.e. after crosslinking, of their precursors are selected from the group consisting of methylsilicone resins and / or phenylsilicones and / or methyl-phenyl-silicones, methylsilicone-polyester resins (copolymers), phenylsilicone-polyester resins (copolymers), methyl-phenylsilicone polyester resins (copolymers), silicone resin-alkyd resins (copolymers), modified silicone resins and mixtures thereof.

[0104] Advantageously, the one or more silicone resins are selected from the group consisting of methylsilicone and / or phenylsilicone and / or methylphenyl-silicone or methylsilicone-polyester resins (copolymers), phenylsilicone-polyester resins (copolymers), methyl-phenylsilicone-polyester resins (copolymers), silicone-alkyd resins (copolymers), modified silicone resins and mixtures thereof.

[0105] The silicone resin may be obtained from a precursor chosen in particular from silicone hydrides, silicone resins containing at least one vinyl group (-CH=CH), 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.

[0106] The silicone resin of the single layer (3) forms a network that can consist of a combination of four single organosiloxane units, designated M, D, T and Q, depending on the degree of substitution of silicon atoms with oxygen, as described in the table below, where R is an organic substituent as described below.

[0107] [Table 1]

[0108] Organopolysiloxane materials or polymers are obtained by crosslinking precursors, which can be monomers or polymers, or by using intermediates, which can be oligomers. Organopolysiloxane polymers can also be obtained from mixtures of these different types of precursors. The crosslink density is higher when the network contains more 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 within the precursor.

[0109] The polymer precursors are organopolysiloxanes. These macromolecules are formed from M, D, T, and / or Q units as listed in the Tables, where R is independently an alkyl group, particularly methyl, or an aryl group, particularly phenyl, and different types of R can be present on the same macromolecule.

[0110] Organopolysiloxanes can be either linear or slightly branched (mainly D groups), or branched or highly branched (mainly T and Q groups). Linear or slightly 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 networks on the scale of individual macromolecules and are called silicone resins. At room temperature, the resins are either substantially solid or, provided they have a fairly low molecular weight, liquid, in the form of a solution in a solvent or in the form of an aqueous emulsion. They can be copolymerized with silicon-free organic polymers or oligomers, especially those selected from polyester, acrylic, alkyd, polyurethane, and epoxy resins.

[0111] When the crosslinking is a hydrolysis-polycondensation, it is carried out using hydroxy or alkoxy reactive functional groups present on the organopolysiloxane, in particular methoxy, ethoxy or butoxy.

[0112] When the crosslinking is polyaddition (or hydrosilylation), it is carried out by reaction between reactive vinyl functional groups (-CH=CH2) present on one of the organopolysiloxanes and reactive silyl-hydride functional groups (Si-H) present on the other organopolysiloxane that is mixed with the first one.

[0113] All of these reactive functional groups are present in at least one number on each organopolysiloxane, and can be present in two, three, or more numbers as long as the molecular structure allows. Silicone oils containing at least one reactive functional group are called "reactive oils." The reactive functional groups can be at the end of the macromolecular chain or distributed along the chain.

[0114] The silicone-polyester resins in particular have a silicone / polyester weight ratio 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.

[0115] Linear PDMS silicone oils, either pure or pre-emulsified in water, are characterized primarily by their molecular weight, which is a direct function of the viscosity of the pure oil. They are then characterized by the presence or absence of reactive functional groups, such as hydroxyls (silanols) on the silicon atoms, their number, and their position on the molecular chain. For example, reactive oils with viscosities of 50 to 20,000 mPa.s, especially 300 to 5,000 mPa.s, can be used, and they have at least one reactive functional group, preferably at least two, which can be located at the ends of the chain.

[0116] Polymer precursors that react by polyaddition can include, for example, polymethylhydrosiloxanes, vinylmethylsiloxanes, vinyl-terminated, especially linear, polydimethylsiloxanes (PDMS), vinyl-terminated diphenylsiloxane-dimethylsiloxane copolymers, hydride-terminated polydimethylsiloxanes, hydride-terminated polyphenylmethylsiloxanes, cyclic vinylmethylsiloxanes, vinyl-MQ resins, trimethylsilyl-terminated polymethylhydrosiloxanes, trimethylsiloxane-terminated copolymers of methylhydrosiloxane and dimethylsiloxane, MQ resin hydrides, and the like, as well as combinations thereof.

[0117] The polymer precursors reacting by hydrolysis-polycondensation, whether silicone resins or silicone oils, can 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 copolymers of diphenylsiloxane-dimethylsiloxane, poly(2-acetoxyethylsilsesquioxane), organically modified alkoxysilanes and their oligomers, and all similar macromolecules, as well as mixtures thereof.

[0118] Organopolysiloxane materials or polymers can also be obtained by crosslinking a mixture of one or more monomer precursors and one or more polymer precursors, as described above, and one or more oligomeric precursors, which may be linear, branched, or cyclic. These oligomeric precursors have a lower molecular weight than the polymeric precursors. To promote a high crosslink density in the final polymeric organopolysiloxane, polymers and / or oligomeric precursors containing more than two, and advantageously much more than two, reactive functional groups can be added to the mixture as a "co-binder."

[0119] The monomers and / or polymer precursors, especially silicone resins, whether copolymerized with an organic polymer or not, act as polymer binders to obtain a solid organopolysiloxane polymer combined with the thermoplastic resin of each layer.

[0120] Silicone oil-type organopolysiloxane precursor oils can be considered additives when added in small amounts (typically 0.1-5% dry) to the overall formulation of a layer, independent of other ingredients for the formation of a solid organopolysiloxane polymer.

[0121] Crosslinking may require a catalyst. In the case of crosslinking of organopolysiloxanes by hydrolysis-polycondensation, the formulation may contain metal catalysts such as metal complexes based on the metals platinum, tin, zinc, zirconium and cerium, in particular platinum-cyclovinylmethyl-siloxane complexes, tin ethylhexanoate, zinc ethylhexanoate, zirconium ethylhexanoate, cerium ethylhexanoate and tin dibutyllaurate. When crosslinking organopolysiloxanes by hydrosilylation, the addition of a catalyst may be necessary, which may be, for example, platinum or a suitable platinum-based catalyst such as Karstedt's catalyst or Ashbys' catalyst.

[0122] A crosslinker may be present, for example a crosslinker having a Si-H bond.

[0123] According to one embodiment, the proportion of silicone resin in each layer (3b) is greater than or equal to 20% by weight relative to the total weight of layer (3b).

[0124] According to another embodiment, the proportion of silicone resin in layer (3b) is greater than or equal to 40% by weight relative to the total weight of layer (3b), respectively.

[0125] According to one embodiment, the proportion of silicone resin in layer (3b) is greater than or equal to 50% by weight relative to the total weight of layer (3b), respectively.

[0126] According to one embodiment, the proportion of silicone resin in each layer (3c) is greater than or equal to 20% by weight relative to the total weight of layer (3c).

[0127] According to another embodiment, the proportion of silicone resin in layer (3c) is greater than or equal to 40% by weight relative to the total weight of layer (3c), respectively.

[0128] According to yet another embodiment, the proportion of silicone resin in each layer (3c) is equal to or greater than 50% by weight relative to the total weight of the layer (3c).

[0129] According to one embodiment, the proportion of silicone resin in one or more layers (3ab) is each equal to or greater than 20% by weight relative to the total weight of layer (3ab).

[0130] According to another embodiment, the proportion of silicone resin in one or more layers (3ab) is greater than or equal to 40% by weight relative to the total weight of each layer (3ab).

[0131] According to yet another embodiment, the proportion of silicone resin in one or more layers (3ab) is equal to or greater than 50% by weight relative to the total weight of each layer (3ab).

[0132] thermoplastic polymer Advantageously, the one or more thermoplastic polymers are selected from the group consisting of aromatic thermoplastic polymers such as polyaryletherketones (PAEKs), poly(arylethersulfones) (PAESs), poly(arylene sulfides) (PASs) or poly(phenylene oxides) (PPOs), liquid crystal polymers, heterocyclic thermoplastic polymers, and mixtures thereof.

[0133] PAEK Advantageously, the one or more polyaryletherketones (PAEK) are selected from the group consisting of polyetherketones (PEK), polyetheretherketones (PEEK), polyetherketoneketones (PEKK), polyetheretherketoneketones (PEEKK) and polyetherketoneetherketoneketones (PEKEKK), particularly preferably PEEK.

[0134] Other aromatic thermoplastic polymers Aromatic thermoplastic polymers include, by way of example according to the present invention, poly(phenylene oxide) (PPO), poly(aryl ether sulfone) (PAES) polymers, in particular polyether sulfone (PES), polyphenylene ether sulfone (PPSU), poly(arylene sulfide) (PAS), and in particular polyphenylene sulfide (PPPS), liquid crystal polymers, and mixtures thereof.

[0135] Heterocyclic Thermoplastic Polymers Heterocyclic thermoplastic polymers according to the present invention include, by way of example, polyetherimides (PEI), polyimides (PI), polyamideimides (PAI) and polybenzimidazoles (PBI), or mixtures thereof.

[0136] Advantageously, the one or more thermoplastic polymers are selected from the group consisting of polyethersulfone (PES), polyphenylene ether sulfone (PPSU), polyamideimide (PAI), polyimide (PI), poly(phenylene oxide) (PPO), poly(arylene sulfide) (PAS), polyetherimide (PEI), polybenzimidazole (PBI), liquid crystal polymer (LCP), polyphenylene sulfide (PPS), polyaryletherketone (PAEK) including polyetherketone (PEK), polyetheretherketone (PEEK), polyetherketoneketone (PEKK), polyetheretherketoneketone (PEEKK), polyetherketoneetherketoneketone (PEKEKK) and mixtures thereof.

[0137] According to an alternative, the PAEK is used in the form of a suspension, the particles of PAEK in the PAEK suspension having a particle size distribution with a d50 of approximately 10 μm to 15 μm.

[0138] Advantageously, the nature of the one or more thermoplastic polymers in layers (3b) and (3c) may be the same or different.

[0139] Advantageously, layer (3b) comprises one or more thermoplastic polymers, preferably less than 30% by weight of said layer, preferably less than 20%.

[0140] Advantageously, layer (3c) comprises one or more thermoplastic polymers, preferably less than 50% by weight of said layer, preferably less than 40%.

[0141] Advantageously, one or more layers (3ab) comprise one or more thermoplastic polymers, preferably less than 50% by weight of said layer, preferably less than 40%.

[0142] According to one embodiment, layers (3b) and (3c) comprise one or more thermoplastic polymers, the proportion of thermoplastic polymer in layer (3c) being preferably greater than the proportion of thermoplastic polymer in layer (3b).

[0143] According to another embodiment, layers (3b) and (3c) comprise one or more thermoplastic polymers, the proportion of thermoplastic polymer in layer (3b) being greater than the proportion of thermoplastic polymer in layer (3c).

[0144] Filler Fillers according to the present invention can provide hydrophobic properties while providing mechanical reinforcement and improving the mechanical strength and thermal conductivity of the coating.

[0145] Fillers can not only provide but also contribute color to the coating.

[0146] The presence of fillers with good thermal conductivity can compensate for the low thermal conductivity of PAEK polymers.

[0147] Advantageously, the one or more fillers are selected from the group consisting of ceramic (such as SiO2) and / or mineral and / or metallic (such as Al2O3, TiO2) and / or silica and / or diamond particle fillers.

[0148] Preferably, the one or more fillers are selected from the group consisting of metal oxides, metal carbides, metal oxynitrides, metal nitrides and mixtures thereof.

[0149] Advantageously, said metal is a transition metal, such as an element chosen from at least B, Ni, Ti, Zr or Hf.

[0150] Even more preferably, the one or more fillers are Reinforcing filler: hard organic or inorganic filler. The hard inorganic filler preferably comprises particles of silicon carbide or alumina or zirconia, or graphite, or ceramic, or carbonate, or hydrated alumina, aluminum hydroxide, or one or more metal oxides, graphite, graphene. - other reinforcing fillers selected from metal oxides: silica, mica, laminar fillers, clays such as montmorillonite, sepiolite, gypsum, kaolinite and laponite, zinc dioxide, quartz, and zirconium phosphate, alumina, zirconia, zinc oxide, copper oxide, and iron oxide. - Filler chosen from reinforcing fibers: glass, carbon or aramid fibers. Conductive fillers 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. - Lamellar fillers that can provide lubricating properties, such as clay, graphene or graphite.

[0151] Preferred fillers for combination with the organopolysiloxane are: Reinforcing fillers: silica or carbonates with a filler content of at least 10-15% by weight and at most 60% by weight; -alumina, hydrated alumina, aluminum hydroxide, -D50<0.1μm and BET specific surface area>30m 2 / g, preferably 30 to 500m 2 / g of silica (precipitated or pyrogenic), -or mixtures of quartz and silica, diatomaceous earth or crushed quartz, titanium, mica, talc, kaolin, barium sulfate, hydrated lime, zinc oxide, expanded vermiculite, non-expanded vermiculite, calcium carbonate, etc.

[0152] Even more preferably, the one or more fillers are selected from alumina, silicon carbide, tungsten carbide, boron nitride, quartz, and mixtures thereof.

[0153] Advantageously, the filler has an average diameter D50 of between 0.1 and 50 μm, more advantageously between 5 and 15 μm.

[0154] Advantageously, the proportion of filler in the layer is between 0.5 and 30% by dry weight, preferably between 5 and 20%, relative to the total weight of said layer after hardening.

[0155] Advantageously, the proportion of filler in layer (3b) is less than 10% by weight relative to the total weight of said layer.

[0156] Advantageously, the proportion of filler in layer (3c) is less than 10% by weight relative to the total weight of said layer.

[0157] Advantageously, the proportion of filler in layers (3b) and (3c) is less than 10% by weight relative to the total weight of layer (3b) / layer (3c), respectively.

[0158] Advantageously, the proportion of filler in one or more layers (3ab) is less than 10% by weight relative to the total weight of said layer.

[0159] Advantageously, the proportions of fillers in layers (3a), (3b) and (3c) may be the same or different.

[0160] Advantageously, the nature of the fillers in layers (3a), (3b) and (3c) may be the same or different.

[0161] additives Advantageously, said additives are selected from the group consisting of antifoaming agents, dispersants, wetting agents, thickeners, pH adjusters, reactive silicone oils.

[0162] The one or more antifoaming agents are preferably selected from the group consisting of mineral oils, diols, hydrocarbons, glycerides, oxiranes and emulsified fatty acids.

[0163] The one or more surfactants are preferably selected from the group consisting of glycol ethers, ethoxylated alcohols excluding alkylphenol ethoxylates (APEs), and gemini surfactants.

[0164] The one or more dispersants are preferably selected from the group consisting of anionic dispersants such as fatty acid derivatives.

[0165] The thickener is preferably selected from the group consisting of acrylic or polyurethane copolymers, cellulose and pyrogenic silica.

[0166] The pH adjuster is preferably selected from the group consisting of Bronsted bases: ammonia, amines (triethylamine, triethanolamine...), hydroxides (sodium, potassium, etc.), carbonates.

[0167] Advantageously, the proportion of additives in layer (3a) is less than 20% by weight relative to the total weight of said layer.

[0168] Advantageously, the proportion of additives in layer (3b) is less than 20% by weight relative to the total weight of said layer.

[0169] Advantageously, the proportion of additives in layer (3c) is less than 20% by weight relative to the total weight of said layer.

[0170] Advantageously, the proportion of additives in layers (3a), (3b) and (3c) is less than 20% by weight relative to the total weight of layers (3a) / (3b) / (3c).

[0171] Advantageously, the proportion of additives in one or more layers (3ab) is less than 20% by weight relative to the total weight of said layer.

[0172] coloring agent Advantageously, the one or more colorants are selected from the group consisting of thermochromic pigments, thermostable pigments, flakes (preferably holographic flakes), and mixtures thereof.

[0173] Advantageously, the proportion of colorant in layers (3b) and (3c) is between 0.5 and 50% by dry weight relative to the total weight of said layers after curing.

[0174] Advantageously, the proportion of colorant in layer (3b) ranges from 10% to 40% by weight relative to the total weight of said layer.

[0175] Advantageously, the proportion of colorant in layer (3c), if present, is less than 10% by weight relative to the total weight of said layer.

[0176] Advantageously, the proportions of colorants in layers (3b) and (3c) may be the same or different.

[0177] Advantageously, the nature of the colorants in layers (3b) and (3c) may be the same or different.

[0178] Thermochromic pigments Preferably, the one or more thermochromic pigments are Bi2O3, Fe2O3, V2O5, WO3, CeO2, In2O3, Y 1.84 Ca 0.16 Ti 1.84 V 0.16 O 1.84 , AgI, Br or (Bi 1-x A x )(V 1-y M y )O4, wherein -x is equal to 0 or x is between 0.001 and 0.999; - y is equal to 0 or y is between 0.001 and 0.999; A and M are selected from the group consisting of nitrogen, phosphorus, alkali metals, alkaline earth metals, transition metals, poor metals, metalloids, or lanthanides; A and M are different from each other.

[0179] If we understand that A and M are different from each other, then the following is the case. -A is an alkali metal and can be selected from Li, Na, K, Rb, and Cs. -M is an alkali metal and can be selected from Li, Na, K, Rb, and Cs. A is an alkaline earth metal and can be selected from Be, Mg, Ca, Sr, Ba. M is an alkaline earth metal and can be selected from Be, Mg, Ca, Sr, Ba. -A is a transition metal and can be selected from Sc, TiCr, Mn, Fe, Co, Ni, Cu, Y, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Ta, W, Ir. M is a transition metal and can be selected from Sc, TiCr, Mn, Fe, Co, Ni, Cu, Y, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Ta, W, Ir. -A is a poor metal and can be selected from Al, Zn, Ga, In, and Sn. -M is a poor metal and can be selected from Al, Zn, Ga, In, and Sn. A is a semimetal and can be selected from B, Si, Ge, Sb. -M is a semimetal and can be selected from B, Si, Ge, and Sb. -A is a lanthanide and can be selected from La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu. -M is a lanthanide and can be selected from La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu.

[0180] Preferably, A and M are different from each other and are B and / or Mg.

[0181] Preferably, the pigment (Bi 1-x A x )(V 1-y M y )O4 has a monoclinic scheelite crystal morphology at ambient temperatures.

[0182] Preferably, x and y are 0, i.e., the pigment (Bi 1-x A x )(V 1-y M y )O4 is bismuth vanadate (BiVO4). Advantageously, BiVO4 is used which has a monoclinic scheelite structure at ambient temperature.

[0183] Bismuth vanadate is a yellow inorganic compound of formula BiVO4 that is widely used due to its coloring properties and its lack of toxicity. It is registered in the Color Index International as QI Pigment Yellow 184 and is sold, among others, by Heubach (Vanadur®), BASF (Sicopal®), FERRO (Lysopac), or again Bruchsaler Farbenfabrik (Brufasol®).

[0184] Heat Stable Pigments Preferably, the one or more heat stable pigments are selected from the group consisting of: -Titanium Rutile Yellow Pigment - Bismuth-based yellow pigments, such as stabilized bismuth vanadate (Py 184 ) red pigments, such as perylene red (e.g. PR149, PR178 and PR224), iron oxides -Bismuth oxyhalide orange pigment (PO 85 ) - Bismuth vanadate orange pigment (PO 86 ) -Tin Titanium Zinc Orange Pigment (PO 82 ) -Cerium sulfide orange pigment (PO 75 , P.O. 78 ) -Chromium Antimony Titanium Rutile Orange-Yellow Pigment (PBr 24 ) -Zinc tin rutile orange-yellow pigment (Py 216 ) -zinc tin sulfide niobium oxide orange-yellow pigment (Py 227 ) -Niobium tin double oxide orange-yellow pigment -Co3(PO4)2 -LiCoPO4 -CoAl2O4 -Cr2O3 -TiO2 -Black pigment PBk28 (copper chromite black spinel) - and mixtures thereof.

[0185] flake The flakes that can be used in the context of the present invention can be independently selected from coated or uncoated mica flakes, coated or uncoated silica flakes, coated or uncoated aluminum flakes, and coated or uncoated iron oxide flakes. Titanium dioxide-coated mica or silica flakes. The flakes that can be used in the context of the present invention can be treated to impart specific color effects.

[0186] Advantageously, the one or more flakes are particles selected from the group consisting of mica, aluminium, titanium dioxide coated mica particles, or mixtures thereof.

[0187] Holographic Flakes Advantageously, one or more of the flakes are holographic flakes, ie a mixture of magnetisable and non-magnetisable particles.

[0188] The magnetizable particles may advantageously be particles containing at least one ferromagnetic metal. These magnetizable particles may be homogeneous, i.e., made of the same material, or composite, i.e., they have a core-shell structure in which the ferromagnetic metal is located in the core and / or shell of the particle. Examples of composite magnetizable particles include mica flakes coated with iron oxide Fe2O3 or stainless steel fibers coated with a sol-gel material, in particular as protection against corrosion during the coating step, or flakes made of a plastic material and coated with iron oxide Fe2O3, or flakes whose core is made of a ferromagnetic metal and whose shell is formed of a plastic material or a sol-gel material.

[0189] According to one embodiment, some of said magnetizable particles are oriented to form a three-dimensional decoration.

[0190] Advantageously, the mixture of magnetizable and non-magnetizable particles is present in an amount between 1% and 5% by weight, preferably between 2% and 3% by weight of the layer.

[0191] Advantageously, the proportion of non-magnetizable particles in the mixture of magnetizable and non-magnetizable particles is between 15% and 40% by weight relative to the total weight of the mixture of magnetizable and non-magnetizable particles.

[0192] Advantageously, the magnetizable particles have a size d50 less than or equal to 23 μm.

[0193] Advantageously, the non-magnetizable particles have a size d90 that is between 20% and 250% of the size d90 of the magnetizable particles.

[0194] Advantageously, the magnetizable particles and / or the non-magnetizable particles are colored on the surface.

[0195] Advantageously, the non-magnetizable particles are in the form of mica, aluminium or titanium dioxide coated mica.

[0196] Advantageously, the magnetizable particles are formed of iron, iron oxide, iron-coated aluminium or iron-coated mica, the iron being in ferrite form.

[0197] decoration According to one embodiment, the one or more layers (3b) are continuous and cover the entire layer (3a) (see Figure 1).

[0198] According to another embodiment, one or more layers (3b) do not cover the entire layer (3a) but form at least one decoration (see figure 2).

[0199] Advantageously, one or more layers form a plurality of decorations, one (i) comprising one or more thermochromic pigments and the other (j) comprising at least one reference temperature pigment composition (see Figure 3).

[0200] According to one embodiment, each of the two decorations (i) and (j) is in the form of adjacent, non-overlapping patterns, for example, each decoration is represented by different geometric patterns that are uniformly distributed over the entire surface and alternate with respect to each other (see FIG. 4A).

[0201] According to another embodiment, the two decorations (i) and (j) are partially overlapping, for example each decoration is represented by a different overlapping geometric pattern evenly distributed over the surface (see FIG. 4B).

[0202] Preferably, the two decorations (i) and (j) overlap either because one of the two decorations is a continuous layer and the other decoration covers it in the form of a pattern, or because the two decorations (i) and (j) are in the form of overlapping patterns (see Figure 4C).

[0203] method The present invention also relates to a method for producing the coated cooking element (1) according to the invention, comprising the following successive steps: i. providing a metal substrate (2) comprising at least one surface (2a) intended to be coated; ii. optionally, pretreating the surface (2a) of the metal substrate intended to be coated; iii. applying an enamel base layer (3a); iv. curing the layer applied in step iii to obtain a base layer (3a); v. Optionally, applying at least one intermediate layer (3b), typically by pad printing, screen printing, inkjet printing, or flexographic printing; vi. Optionally, drying the one or more intermediate layers (3b); vii. applying at least one finishing layer (3c); viii. Curing all base layers (3a), intermediate layers (3b) and finish layers (3c).

[0204] According to one embodiment, at least one intermediate layer (3b) is applied to the at least one base layer (3a) and / or at least one finishing layer (3c) is applied to the at least one intermediate layer (3b).

[0205] Advantageously, the steps of the method according to the invention make it possible to coat a metal substrate (2) with a coating (3) formed by three layers: (3a), optionally (3b) and (3c). Generally, these three layers are wet when applied. In the context of the present invention, "wet layer" is understood to mean that the layer contains all or part of its solvent.

[0206] Preferably, all of the solvent in the wet layer is removed naturally or by physical treatment, such as heat drying, air drying, or vacuum treatment.

[0207] Advantageously, the coating composition according to the invention may also comprise at least one solvent. Advantageously, the solvent may be a protic solvent. Advantageously, the solvent may be non-toxic.

[0208] The solvent that can be used in the coating composition according to the invention can advantageously comprise at least one alcohol, preferably chosen from isopropanol, methanol, ethanol, and mixtures thereof.

[0209] The application of the coating is carried out in several layers. In this case, the deposition of at least one layer of the coating (3) according to the invention on at least one of the two opposite faces of the substrate is repeated several times. Preferably, a drying step is carried out between the application of each layer (3b) and (3c), followed by curing of the coated substrate after the application of the last layer. The application of the coating (3) according to the method according to the invention to the substrate (2) makes it possible to obtain a layer of a heat-stable coating.

[0210] The coating formulation to be coated is generally in aqueous form, with the polymer of the polymer phase being in the form of a suspension. Other non-aqueous solvents may also be suitable.

[0211] Advantageously, the method for producing the coated cooking element (1) according to the invention comprises, after application of each layer (3b) and (3c), one or more drying steps at 80 to 150° C. Drying can be carried out by convection or infrared radiation.

[0212] The application of the coating according to the invention can be carried out by the method according to the invention on the shaped substrate or even on locally flat areas of the shaped substrate. A heat-stable coating layer is obtained. This coating layer is generally wet.

[0213] Advantageously, the method for producing a coated cooking element (1) according to the invention comprises a step of shaping said support (2) before step iii.

[0214] The coating is preferably applied by spraying.

[0215] The method according to the invention comprises a step viii of curing the element obtained in step vii of the method. In the context of the present invention, "curing the coated substrate" is intended to mean a heat treatment that makes it possible not only to densify one or more coating layers applied to the substrate, but also to crosslink the organopolysiloxane (silicone resin) precursor.

[0216] Curing is carried out in step viii. Generally, the curing temperature in step viii is 230°C to 420°C.

[0217] Advantageously, the method for producing the coated cooking element (1) according to the present invention comprises a single final curing step viii of all applied layers (3b) and (3c), which single curing process is carried out simultaneously for all applied layers (3b) and (3c).

[0218] In the context of the present invention, "curing the coated substrate" in step viii is intended to mean a heat treatment that makes it possible not only to densify the one or more coating layers (3b) and (3c) applied to the substrate, but also to crosslink the organopolysiloxane (silicone resin) precursor.

[0219] The application steps iii. and vii. can be carried out by electrostatic powder coating, solvent or aqueous phase spraying, screen printing, roller or digital printing. Preferably, especially step vii. is carried out by electrostatic powdering or by solvent or aqueous phase spraying.

[0220] Typically, the substrate has the final shape of the cooking utensil, with a concave inner surface (2a) intended to be placed on the side where food can be introduced into the article, and a convex outer surface intended to be placed on the heat source side.

[0221] Curing step iv is typically carried out at temperatures between 540°C and 580°C, generally for at least 3 minutes. Thus, the enamel layer cures before the intermediate layer (3b) and the finishing layer (3c), since certain components of these layers, particularly polymeric components, may decompose or thermally decompose at these temperatures.

[0222] According to the present invention, step iii. of producing the base layer (3a) comprises the following sub-steps: a) preparing an aqueous slip for an enamel glaze, said enamel glaze having less than 50 ppm cadmium and less than 50 ppm lead, comprising 30-40% by weight of silica and 15-30% by weight of titanium oxide, less than 10% by weight of vanadium oxide and less than 4% by weight of lithium oxide, based on the total weight of the glaze, and the aqueous slip comprising at least 20% by weight of mineral filler based on the total weight of the slip; b) applying the aqueous slip formed in step a) to the inner surface of the support by spraying the slip, followed by drying to form a green enamel layer.

[0223] Unlike electric arc or plasma spraying, no homogeneous compound is applied during step iii, and its structure after hardening is determined by its initial chemical composition before hardening. In fact, during step iii, an aqueous slip of enamel glaze is applied, and during hardening, a homogenization of the various fusible elements of the slip, those originating from the enamel glaze and those originating from the slip formulation, is observed. Therefore, there is no clear correspondence between the composition of the slip and the structure of the enamel formed after steps iii and iv.

[0224] According to a particularly advantageous embodiment, the aqueous slip of the enamel glaze does not contain any solvents and therefore does not produce any VOCs, and the enamel glaze used contains almost no or only trace amounts (maximum 50 ppm of harmful elements) of harmful elements such as lead or cadmium, so that the enamel thus obtained complies with food industry legislation, both in terms of the formulation of the enamel glaze as well as the formulation of the slip.

[0225] Advantageously, the enamel glaze comprises: · AI2O3: Less than 1% ·B2O3: Less than 1% BaO: less than 1% ·K2O: 5~20%, Li2O: less than 4% ·Na2O: 10~25%, P2O5: less than 4% SiO2: 30-40%, ·TiO2: 15~30%, ·V2O5: Less than 10%. The content is expressed as a weight percentage relative to the weight of the glaze.

[0226] Advantageously, the enamel glaze slip also comprises: ·Quartz: 5~30%, ·SiC: 10~30%, Pigment: 1-10% ·Suspending agent: 2~10%, The content is expressed as a mass percentage relative to the total weight of the slip.

[0227] To produce the first variant with a discontinuous base layer (3a), the application of the slip onto the face (2a) of the substrate (2) is carried out, for example, by pneumatic spraying at a spray pressure of 2 to 5 bar, the amount of enamel deposited on said face (2a) being 1.5 g / dm 2 ~2.8g / dm 2 is.

[0228] To produce a second variant with a continuous base layer (3a), the application of the slip onto the face (2a) of the substrate (2) is carried out, for example, by pneumatic spraying at a spray pressure of at least 4 bar, and the amount of enamel deposited on said face (2a) is 0.07 g / dm 2 ~0.2g / dm 2 is.

[0229] Step ii. of pretreating the surface (2a) can comprise mechanical treatments such as sandblasting, shot blasting and / or shot peening, and / or chemical treatments such as degreasing, satin finishing and / or rinsing. Advantageously, step ii. comprises degreasing followed by mechanical and / or chemical treatments.

[0230] Preferred Embodiments According to one embodiment, the present invention relates to a coated cooking element (1) for a cooking utensil or electric cooking appliance, comprising a metal substrate (2) coated on at least one side (2a) with the following three layers, or exclusively with the following three layers, superimposed in this order starting from the metal substrate (2): (3a) A base layer comprising or consisting of a rough enamel layer containing less than 50 ppm of lead and less than 50 ppm of cadmium, having the following characteristics: - a hardness higher than the hardness of the metal substrate constituting the support (2), a melting point between the melting point of the metal substrate constituting the support (2) and the melting point of one or more components of the intermediate layer (3b) and the finishing layer (3c), and Surface roughness Ra of -2 to 50 μm, a base layer having (3b) optional one or more intermediate layers, preferably two intermediate layers, containing one or more colorants and, optionally, one or more silicone resins, and / or one or more thermoplastic polymers, and / or one or more fillers, and / or - one or more additives one or more intermediate layers, (3c) A finish layer intended to come into contact with food during cooking, comprising one or more silicone resins and, optionally, one or more thermoplastic polymers, and / or one or more fillers, and / or one or more additives, and / or -flake A finishing layer consisting of

[0231] The finishing layer (3c) is advantageously continuous.

[0232] Advantageously, if the base layer (3a) is discontinuous, its thickness is preferably between 10 μm and 50 μm, and if the base layer (3a) is continuous, its thickness is preferably between 50 μm and 100 μm.

[0233] Preferably, the colorants of the one or more intermediate layers (3b) comprise pigments and / or flakes, advantageously holographic flakes.

[0234] According to an alternative, the one or more intermediate layers (3b) consist of: one or more colorants, in particular pigments and / or flakes, advantageously holographic flakes, 0-10% filler, 0-20% additives, one or more silicone resins, and Optionally, one or more thermoplastic polymers advantageously chosen from polyamideimides (PAI), polyimides (PI), polyetherimides (PEI), polybenzimidazoles (PBI), polyethersulfones (PES), polyphenylene ether sulfones (PPSU), polyaryletherketones (PAEK), and mixtures thereof.

[0235] According to another alternative, the one or more intermediate layers (3b) consist of: one or more colorants, in particular pigments and / or flakes, advantageously holographic flakes, one or more thermoplastic polymers advantageously chosen from polyamideimides (PAI), polyimides (PI), polyetherimides (PEI), polybenzimidazoles (PBI), polyethersulfones (PES), polyphenylene ether sulfones (PPSU), polyaryletherketones (PAEK), and mixtures thereof, 0-10% filler, 0-20% additives, One or more silicone resins.

[0236] According to a particular embodiment, the coating comprises two intermediate layers (3b), at least one of which is a decorative layer. Advantageously, one or more layers (3b) form the decoration, one (i) comprising one or more thermochromic pigments and the other (j) comprising at least one reference temperature pigment composition.

[0237] Typically, the thickness of the one or more assemblies of intermediate layers (3b) is between 3 μm and 10 μm.

[0238] Preferably, the intermediate layer (3b) covers only a portion of the base layer (3a), in other words, the intermediate layer may be continuous or discontinuous, and the coverage of the base layer is strictly less than 100%, for example, 0.1 to 80%, particularly 1 to 10%.

[0239] According to one embodiment, the finishing layer (3c) consists of one or more silicone resins and optionally one or more thermoplastic polymers.

[0240] Typically, the thickness of the layer (3c) is 0.1 μm to 10 μm.

[0241] In a particular embodiment, the thickness of layer (3b) is 3 μm to 10 μm, and the thickness of layer (3c) is 0.1 μm to 10 μm.

[0242] Goods The present invention also relates to a cooking utensil (100) that includes the coated cooking element (1).

[0243] According to one embodiment, the cooking utensil (100) has a heating surface (6) intended to be in contact with an external heat source, opposite a cooking surface (5) intended to be in contact with food during cooking. The cooking surface (5) is typically the surface (2a) intended to be coated with the coating of the present invention.

[0244] Advantageously, the cooking utensil (100) according to the invention is selected from the group consisting of a saucepan, a frying pan, a fondue or raclette pan or pot, a stewpot, a wok, a sauté pan, a crepe maker, a grill, a plancha grill, a cooking pot, a casserole, a container for a cooker or bread machine, a cooking mould.

[0245] The present invention also relates to an electric cooking appliance (200) comprising a coated cooking element (1) according to the present invention and a heat source (210) designed to heat said coated cooking element (1).

[0246] Advantageously, the electric cooking appliance (200) is selected from the group consisting of an electric crepe maker, an electric raclette maker, an electric fondue maker, an electric grill, an electric plancha grill, an electric cooker, a bread maker, an electric pressure cooker, a waffle maker, a rice cooker and a jam maker.

[0247] A cooking utensil according to the invention may in particular be a cooking utensil in which one of the two opposite faces of the substrate is an inner face, optionally concave, intended to be placed on the side of food likely to be introduced onto or into said product, and the other face of the substrate is an outer face, optionally convex, intended to be placed facing a heat source.

[0248] By way of non-limiting example, cookware according to the present invention include cookware such as pots and pans, woks and sauté pans, stew pots and casseroles, crepe makers, baking pans and trays, barbecue plates and grills, and cooking bowls, among others. [Example]

[0249] The following examples are given by way of illustration only and should not be construed as limiting the invention in any way.

[0250] Metal substrate: This is an aluminum support that is sandblasted or shot peened and then passed through a suitable surface treatment to remove organic contaminants.

[0251] The raw materials of layer (3a) according to Example 3 are detailed below.

[0252] Raw materials for the intermediate layer (3b), (3b') and the finishing layer (3c) -Silicone resin RS1: Ethoxy-functionalized silicone-polyester resin in solvent phase (80% silicone / 20% polyester), viscosity approx. 2000 mPas at 25°C, solids content = 75% RS2: Ethoxy-functionalized silicone-polyester resin in solvent phase (50% silicone / 50% polyester), viscosity approx. 2000 mPas at 25°C, solids content = 75% RS2: Ethoxy-functionalized silicone-polyester resin in solvent phase (30% silicone / 70% polyester), viscosity approx. 2000 mPas at 25°C, solids content = 75% RS4: Methylphenyl-functionalized silicone-polyester resin in solvent phase, viscosity approx. 2000 mPas at 25°C, solids content = 75% RS5: Ethoxy-functionalized silicone-polyester resin in solvent phase (50% silicone / 50% polyester), viscosity approx. 2000 mPas at 25°C, solids content = 75% RS6: Ethoxy-functionalized methylorganopolysiloxane resin in aqueous emulsion, viscosity at 25°C approx. 1500 mPas, solids content = 52%

[0253] -Alcohol solvent Dipropylene glycol butyl ether (DPNB) 2-Methoxy-1-methylethyl acetate (MPA) Butyl glycol acetate (BGA) Butyl acetate

[0254] -Surfactants and antifoaming agents Mineral oil: Tego Foamex K7 from Evonik Fatty alcohol polyglycol ether: Clariant's Genapol X080 or Tergitole TMN-100X

[0255] -Reinforcing fillers Pyrogenic silica: Levasil CC301, Dimethyldichlorosilane post-treated fumed silica: AEROSIL R972

[0256] -Pigments Mica: Iriodin 100 or Iriodin 300 and / or Magnapearl 5000 Cr / Fe oxide: Sicoapal Black K0098FK Carbon black: Derussol F25 or Cabot Monarch 4750 Perylene red (PR178). Iron Oxide III: H856 Brick

[0257] -Acrylic resin: Rohagit SD 15: 30% acrylic polymer solution in water phase

[0258] -Silicone oil Polyether-modified polysiloxane: TEGO GLIDE 100, Polydimethylsiloxane oil: CT 601M

[0259] -Other additives AMP90: Solution of 2-amino-2-methyl-1-propanol: 90% polymer in aqueous phase, buffer Metolat 368: fatty acid ester, Dolfynox 1030: Propoxylated polyglycol ether, wetting agent Edaplan LA451: Anionic ester in ethanol / water, wetting agent Tego Glide 407: Methylphenyl polysiloxane, flow agent

[0260] Operating principle of jar mill (mechanical grinding) Ball milling involves placing the sample to be ground and so-called grinding balls in a jar and rotating the jar around its axis at a constant speed. Rotation of the jar is generally performed using a roller machine. The sample can be ground in dry form or dispersed in a suitable solvent (e.g., in water or alcohol). The dispersion can also contain specific adjuvants (such as dispersants or antifoaming agents).

[0261] The median diameter of the grinding balls must be adapted to the size of the particles to be ground. The finer the particles, the smaller the diameter of the balls used. The total volume of the balls, including the voids between them, is approximately 50-60% of the internal volume of the jar. Balls of different sizes are advantageously distributed according to the following weight ratio relative to the total weight of the balls: 25% small balls, 50% medium balls, and 25% large balls. The minimum size of the balls is 2-10 mm. Stabilized alumina and zirconia are commonly used ball materials.

[0262] Example 1 Preparation of enamel glaze F1 according to the enamel glaze used in the method of the present invention The enamel glaze F1 is prepared according to the enamel glaze used in the method of the invention by melting the following ingredients at 1200°C: Al2O3: 0.1% B2O3:0.6% BaO: 0.3% K2O:12 Li2O: 2.3% Na2O:19% P2O5: 1.6% SiO2:35% TiO2: 23.5% V2O5: 5.2%

[0263] Average particle size 15 μm, and linear expansion coefficient 494.10 -7 mK -1 The resulting molten mixture is ground to obtain a powder glaze F1 having the formula:

[0264] Example 2 Preparation of a first example of a slip B1 of an enamel glaze according to the slip used in the method of the invention The enamel glaze F1 is formulated in the form of a slip B1 by mixing the following ingredients (parts by weight): Enamel glaze F1:70 Wednesday:55 Quartz: 25 SiC:23 Black pigments based on Fe and Mn oxides: 5 Boric acid: 4 Therefore, the slip B1 is 1.70 g / cm 3 and a density of 1300 g / m 2 This was obtained as a "setup". As used herein, the term "set up" refers to the amount of material required to evenly cover a given surface after application.

[0265] Example 3 Manufacturing of a first embodiment of a cookware according to the invention having a continuous rigid base (layer 3a) An aluminum carrote obtained by molding an aluminum disc (type 1200) was used as support; the carrote thus formed had a base with a diameter of approximately 28 cm.

[0266] The carrot was degreased by spraying with an alkaline solution, then immersed in a sodium hydroxide bath to give it a satin finish, and finally neutralized with nitric acid, rinsed, and dried. Next, using an air gun, slip B1 from Example 2 was applied to form a continuous layer. The coated carrot was dried at a temperature of 1400°C and then vitrified at 555°C for 5 minutes, resulting in a continuous hard base with a thickness of 50 μm. The roughness Ra of this continuous hard base was 8 μm.

[0267] After this hard base (layer 3a) has cooled, steps v. to viii. of the method according to the invention are carried out.

[0268] Middle layer (3b) A successive layer (3b) is then deposited by spraying onto layer (3a), this layer sequence (3b) being selected from the layer compositions described below: layer 3b1, layer 3b2, and layer 3b3:

[0269] [Table 2]

[0270] [Table 3]

[0271] [Table 4]

[0272] The aqueous composition of layer 3b is prepared by ball gridding. Ball gridding is carried out in a jar as described above. The sample can be ground in dry form or dispersed in a suitable solvent (e.g., in water or alcohol, or in a solvent). The dispersion can also contain specific adjuvants (such as dispersants or antifoaming agents).

[0273] The thickness of this layer (3b) is 10 μm to 20 μm, preferably 12 μm to 15 μm.

[0274] Intermediate layer (3b') and finishing layer (3c) The substrate, to which the base layer (3a) and the successive layer (3b) have been applied as described above, is coated with a multi-layer anti-adhesion coating consisting of an intermediate layer (3b) (6-8 μm) and a finishing layer (3c) (14-18 μm), which are dried at 100 ° C for 4 minutes. The assembly is finally cured at 250 ° C for 1 hour.

[0275] The composition of the intermediate layer (3b') is deposited by spraying: layer 3b'1, layer 3b'2 and layer 3b'3:

[0276] [Table 5]

[0277] [Table 6]

[0278] [Table 7]

[0279] The composition of the finishing layer (3c) is deposited by spraying and is described below: Layers 3c1 to 3c10:

[0280] [Table 8]

[0281] [Table 9]

[0282] [Table 10]

[0283] [Table 11]

[0284] [Table 12]

[0285] [Table 13]

[0286] [Table 14]

[0287] [Table 15]

[0288] [Table 16]

[0289] [Table 17]

[0290] The adhesion of the intermediate layer (3b) and the finishing layer (3c) on the base layer (3a) can be evaluated by immersing the article in boiling water for 9 hours and then carrying out a grid adhesion test according to standard ISO 2409.

[0291] Adhesion to the substrate is generally excellent.

[0292] The anti-adhesion properties of the coating can also be evaluated by the carbonized milk test according to standard NF D21-511.

[0293] The abrasion resistance of the coating can also be evaluated by subjecting it to the action of a green Scotch BRITE type scouring pad. The anti-adhesion properties of the coating can be simultaneously evaluated by the carbonized milk test.

[0294] Methods for characterizing anti-stick coatings: Egg test performance The evaluation method for the anti-stick coating properties is based on the egg test in accordance with standard AFNOR NF D 21-511 paragraph 3.3.2 and is carried out as follows: The sample is washed and any remaining water on the surface is wiped off. The inner surface of the container body is dried in advance. Heat the cooking vessel on a gas range to a temperature of 140-170°C. Crack a 60 / 65 egg and pour it into the center of the hot cooking vessel. Wait until the egg solidifies (6-9 minutes). Remove the egg from the cooking vessel with a spatula and wash off the coating with a damp vegetable sponge, assessing the anti-stick properties of the cooking vessel.

[0295] And the record is made as follows: Score 100: The egg is completely removed using a plastic spatula. Score 75: Eggs are not completely removed, but the coating can be easily cleaned with a damp sponge. Score 50: The egg is not completely removed, but the coating can be cleaned with a damp sponge. Score 25: Egg not completely removed and coating not cleaned with a damp sponge. Grade 0: The eggs are not removed and the coating cannot be cleaned with a damp sponge.

[0296] [Table 18]

[0297] All of the silicone-polyester resin-based coatings according to the present invention exhibit good anti-adhesion properties while adhering to metal.

[0298] Example 4 Preparation of a second example B2 of an enamel glaze slip according to the slip used in the method of the invention The enamel glaze F1 is formulated in the form of a slip B2 by mixing the following ingredients (parts by weight): Above enamel glaze: 85 Wednesday:55 Quartz: 15 SiC:23 Black pigment FA1220:5 Boric acid: 4 Slip is 1.70g / cm 3 and a density of 1300 g / m 2 It has a "setup".

[0299] Example 5 Manufacturing a second embodiment of a cookware according to the present invention having a discontinuous rigid base The same substrate as in Example 3, i.e., a hollow 1200 aluminum carrot, is used, which is degreased by spraying with an alkaline solution, given a satin finish by immersion in a sodium hydroxide bath, then neutralized with nitric acid, rinsed and dried.

[0300] Next, slip B2 of Example 4 is applied using a pneumatic gun in order to obtain a discontinuous enamel layer deposit in the form of separate droplets, as in Example 3. The carrot thus coated with the discontinuous base layer 3a is dried at 140 ° C and then vitrified at 555 ° C for 5 minutes, obtaining a discontinuous layer with a weight of 0.9 g.

[0301] The droplet size and density per unit area are measured by microscopy. The droplet size is 2-50 μm, and the density per unit area is 1500 droplets / mm. 2 The roughness Ra of the layer is measured and a value of Ra=15 μm is obtained.

[0302] After the enamel hard base has cooled, steps v. to viii. of the method according to the invention are carried out as shown in Example 3. As shown in Figures 1, 2 and 3, three alternative embodiments of the intermediate decorative layer (3b) are carried out.

[0303] Example 6 Preparation of a third example B3 of an enamel glaze slip with the slip used in the method of the invention The enamel glaze F1 is formulated in the form of a slip B3 by mixing the following ingredients (parts by weight): Above enamel glaze: 85 Wednesday:55 Quartz:8 SiC:23 Black pigment FA1220:5 Boric acid: 4 Slip is 1.70g / cm 3 and a density of 1300 g / m 2 It has a "setup".

[0304] Example 7 Manufacturing a third embodiment of a cookware according to the present invention having a discontinuous rigid base The same substrate as in Example 3, i.e., a hollow 1200 aluminum carrot, is used, which is degreased by spraying with an alkaline solution, given a satin finish by immersion in a sodium hydroxide bath, then neutralized with nitric acid, rinsed and dried.

[0305] Next, slip B3 is applied using a pneumatic gun to obtain a discontinuous enamel layer deposit in the form of separate droplets, as in Example 3. The carrot thus coated with a discontinuous hard base is dried at 140°C and then vitrified at 555°C for 5 minutes to obtain a discontinuous layer weighing 0.9 g.

[0306] The droplet size and density per unit area are measured by microscopy. The droplet size is 2-30 μm, and the density per unit area is 1500 droplets / mm. 2The roughness Ra of the layer is measured and a value of Ra=6.5 μm is obtained.

[0307] After the enamel hard base has cooled, steps v. to viii. of the method according to the invention are carried out as shown in Example 3. As shown in Figures 1, 2 and 3, three alternative embodiments of the intermediate decorative layer (3b) are carried out.

Claims

1. A coated cooking element (1) for a cooking utensil or electric cooking appliance, comprising a metal substrate (2) coated on at least one surface (2a) with at least the following layers, starting from the metal substrate (2) and in this order: (3a) A base layer comprising or consisting of a rough enamel layer containing less than 50 ppm lead and less than 50 ppm cadmium, - a hardness higher than the hardness of the metal substrate constituting the support (2), a melting point between the melting point of said metal substrate constituting the support (2) and the melting point of one or more components of the intermediate layer (3b) and the finishing layer (3c), and Surface roughness Ra of -2 to 50 μm a base layer having the properties of (3b) one or more optional intermediate layers comprising one or more colorants and, optionally, one or more silicone resins, and / or one or more thermoplastic polymers, and / or one or more fillers, and / or - one or more additives one or more intermediate layers consisting of (3c) a finish layer comprising one or more silicone resins and, optionally, one or more thermoplastic polymers, and / or one or more fillers, and / or one or more additives, and / or -flake A finishing layer consisting of

2. 2. The coated cooking element (1) of claim 1, characterized in that the one or more silicone resins are selected from the group consisting of methylsilicone and / or phenylsilicone and / or methyl-phenyl-silicone resins, methylsilicone-polyester resins (copolymers), phenylsilicone-polyester resins (copolymers), methyl-phenyl-silicone-polyester resins (copolymers), silicone-alkyd resins (copolymers), modified silicone resins, and mixtures thereof.

3. 3. The coated cooking element (1) according to claim 1 or 2, characterized in that the one or more fillers, if present, are selected from the group consisting of ceramic and / or mineral and / or metal and / or silica and / or diamond particle fillers.

4. 4. The coated cooking element (1) of any one of claims 1 to 3, characterized in that the one or more thermoplastic polymers, if present, are selected from the group consisting of polyethersulfone (PES), polyphenylene ether sulfone (PPSU), liquid crystal polymer (LCP), polyphenylene sulfide (PPS), polyamideimide (PAI), polyimide (PI), poly(phenylene oxide) (PPO), poly(arylene sulfide) (PAS), polyetherimide (PEI), and polymenzimidazole (PBI), polyaryletherketone (PAEK) including polyetherketone (PEK), polyetheretherketone (PEEK), polyetherketoneketone (PEKK), polyetheretherketoneketone (PEEKK), polyetherketoneetherketoneketone (PEKEKK), and mixtures thereof.

5. 5. The coated cooking element (1) according to any one of claims 1 to 4, characterized in that the one or more colorants, if present, are selected from the group consisting of thermochromic pigments, thermostable pigments, flakes, and mixtures thereof.

6. The one or more thermochromic pigments are BI ２ O ３ , Fe ２ O ３ , V ２ O ５ , W.O. ３ , CeO ２ , In ２ O ３ , 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 ) O ４ wherein the compound is selected from the group consisting of: -x is equal to 0 or x is between 0.001 and 0.999; -y is equal to 0 or y is between 0.001 and 0.999; A and M are selected from the group consisting of nitrogen, phosphate, alkali metals, alkaline earth metals, transition metals, poor metals, metalloids, or lanthanides; - A and M are different from each other; A coated cooking element (1) according to claim 5.

7. the one or more heat stable pigments - Titanium rutile yellow pigment, - Bismuth-based yellow pigments (e.g. stabilized bismuth vanadate (Py １８４ ) selected from red pigments (for example selected from perylene red, iron oxides), - Bismuth oxyhalide orange pigment (PO ８５ ), - Bismuth vanadate orange pigment (PO ８６ ), - Tin Titanium Zinc Orange Pigment (PO ８２ ), - Cerium sulfide orange pigment (PO ７５ , P.O. ７８ ), - Chromium antimony titanium rutile orange-yellow pigment (PBr ２４ ) - Zinc tin rutile orange-yellow pigment (Py ２１６ ) - Zinc tin sulfide niobium oxide orange-yellow pigment (Py ２２７ ) - Niobium tin double oxide orange-yellow pigment -Co ３ (PO ４ ) ２ -LiCoPO ４ -CoAl ２ O ４ -Cr ２ O ３ -Truth ２ - Black pigment PBk28 (copper chromite black spinel) - and mixtures thereof 7. The coated cooking element (1) according to claim 5 or 6, characterized in that it is selected from the group consisting of:

8. Coated cooking element (1) according to any one of claims 5 to 7, characterized in that the one or more flakes are holographic flakes which are a mixture of magnetizable and non-magnetizable particles.

9. 9. The coated cooking element (1) according to any one of claims 1 to 8, characterized in that the metal substrate (2) is a substrate made from aluminum, stainless steel, cast iron or cast aluminum, iron, titanium, or copper.

10. the thickness of said layer (3a) is between 10 μm and 100 μm, typically between 20 μm and 85 μm, and the thickness of said layer (3b) is between 1 μm and 100 μm, preferably between 2 μm and 30 μm, and the thickness of said layer (3c) is between 0.05 μm and 100 μm, preferably between 0.08 μm and 20 μm; A coated cooking element (1) according to any one of claims 1 to 9, characterized in that:

11. The melting point of the base layer (3a) is 50° C. higher than the highest melting point of the components of the intermediate layer (3b) and the finishing layer (3c), Tf １ and a temperature Tf that is 10° C. lower than the melting point of the metal substrate that constitutes the support (2). ２ Coated cooking element (1) according to any one of claims 1 to 10, characterized in that the coating thickness is between

12. 12. The coated cooking element (1) according to any one of claims 1 to 11, characterized in that the proportion of filler in layers (3b) and (3c), if present, is less than 10% by weight, relative to the total weight of layer (3b) or layer (3c), respectively.

13. 13. The coated cooking element (1) according to any one of claims 1 to 12, characterized in that the proportion of additives in layers (3b) and (3c), if present, is less than 20% by weight, relative to the total weight of layer (3b) or layer (3c).

14. A method for manufacturing a cooking element (1) according to any one of claims 1 to 13, comprising: i. Providing a metal substrate (2) with at least one internal surface (2a) intended to be coated; ii. Optionally, pretreating the surface (2) of the metal substrate (2) intended to be coated; iii. Applying an enamel base layer (3a), advantageously comprising: a) preparing an aqueous slip of an enamel glaze, the enamel glaze having less than 50 ppm cadmium and less than 50 ppm lead, containing 30-40% by weight or less of silica, 15-30% by weight or less of titanium oxide, 10% by weight or less of vanadium oxide, and less than 4% by weight or less of lithium oxide, based on the total weight of the glaze, and the aqueous slip containing at least 20% by weight or less of mineral filler, based on the total weight of the slip; b) applying the aqueous slip formed in step a) onto the lower surface of the substrate (2) by spraying, followed by drying to form an environmentally friendly enamel layer; and iv. curing the layer applied in step (b) to obtain a base layer (3a), typically carried out at a temperature of 540°C to 580°C; v. Optionally, applying at least one intermediate layer (3b); vi. Optionally, drying said one or more intermediate layers (3b); vii. applying at least one finishing layer (3c); viii. Curing all of the base layer (3a), intermediate layer (3b) and finishing layer (3c); A manufacturing method comprising:

15. A cooking utensil (100) comprising a coated cooking element (1) according to any one of claims 1 to 13.

16. 16. Cooking appliance (100) according to claim 15, characterized in that it comprises a heating surface (6) intended to be in contact with an external heat source, said heating surface (6) being opposite a cooking surface (5) intended to be in contact with food during cooking.

17. 17. The cooking implement (100) of claim 15 or 16, selected from the group consisting of a saucepan, a frying pan, a fondue or raclette pan or pot, a stewpot, a wok, a sauté pan, a crepe maker, a grill, a plancha grill, a cooking pot, a pan, a container for a cooker or bread machine, a cooking mold.

18. An electric cooking appliance (200) comprising a coated cooking element (1) and a heating source (210) configured to heat the coated cooking element (1), wherein the coated cooking element (1) is a coated cooking element (1) according to any one of claims 1 to 13.

19. 20. The electric cooking appliance (200) of claim 18, selected from the group consisting of an electric crepe maker, an electric raclette appliance, an electric fondue appliance, an electric grill, an electric plancha grill, an electric cooker, a bread maker, an electric pressure cooker, a waffle maker, a rice cooker, and a jam maker.

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