Fluorine-free silicone resin-based coating containing a temperature indicator

Abstract

The present invention relates to a coated cooking element (1) for a cooking utensil or electric cooking appliance, the coated cooking element (1) having a metal substrate (2) coated on at least one side (2a), the side (2a) being coated, from the metal substrate side, with at least a base layer (3a), one or more intermediate layers (3b), and a finishing layer (3c), in this order, the base layer (3a) comprising: one or more silicone resins, and optionally: one or more thermoplastic polymers; one or more colorants selected from the group consisting of thermochromic pigments, heat-stable pigments, flakes, and mixtures thereof; one or more fillers; and and / or one or more additives; one or more intermediate layers (3b) comprise one or more colorants selected from the group consisting of thermochromic pigments, heat-stable pigments, flakes, and mixtures thereof, and optionally: one or more silicone resins, one or more thermoplastic polymers, one or more fillers, and / or one or more additives; and the finish layer (3c) comprises 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 relates to a method for producing a coated cooking element, and to a cooking utensil or electric cooking appliance comprising the coated cooking element.

Description

[Technical Field]

[0001] The technical field of the invention relates to the field of cooking articles having a coating on one side thereof, and more precisely to silicone resin-based coatings for these articles. [Background technology]

[0002] In the field of cookware, coatings based on fluoroplastics, particularly polytetrafluoroethylene (PTFE), are commonly known for their non-stick and heat-resistant properties. However, these coatings have low mechanical strength.

[0003] WO 2020 / 144051 relates to a fluoropolymer-based coating that has improved mechanical resistance to abrasion due to the incorporation of organic fillers (SiC) and inorganic fillers (Al2O3) into the primer and finish layers of the coating. The performance improvements achieved in terms of mechanical strength are satisfactory but still not optimal.

[0004] The fluoropolymer-based coating is intended for frying pans and saucepans, but its punchability also allows for other applications in the molding sector (molds, cake pans, waffle makers, etc.) or small household appliances (rice cookers, fryer inserts, electric crepe makers).

[0005] An alternative to PTFE coatings is the use of so-called "ceramic" coatings, developed by the sol-gel method and the use of tetraethyl orthosilicate (EP 2806776). These coatings are characterized by being hard and resistant to mechanical wear, but they exhibit brittle behavior and poorer non-stick properties than fluoropolymer-based coatings. Additionally, these coatings lack punchability and are therefore not suitable for moldings and small household appliances.

[0006] In the area of molded articles (consumer or industrial), fluoropolymer-based coatings are less prevalent because of the lower thermal resistance constraints (up to 220°C) and the possibility to use other types of coatings, such as silicones. Pure silicone resins are said to be non-sticky and resistant to temperatures above 220-230°C. In contrast, they are said to have poor adhesion to substrates. Silicone-polyester resins, on the other hand, are widely used in the molding industry because they adhere well to substrates, are non-sticky, and are compatible with die-cutting processes. However, silicone-polyester resins degrade at temperatures above 230°C. In fact, the operating temperature range for cookware is between 50°C and 250°C, and it is not uncommon for induction-heated cookware to reach temperatures of 300°C or even 350°C. Therefore, silicone-polyester resins are not compatible with the operating temperatures in the cookware industry.

[0007] However, controlling the cooking temperature is an essential parameter, since it determines the success or failure of cooking and ensures the maintenance of the physicochemical properties of the non-stick coating. With this in mind, a cooking start temperature indicator has been developed for consumers, whose purpose is to show, by a color change, the temperature at which the consumer can start cooking, thus avoiding the possibility of overheating. Generally, this technology relies on the use of thermochromic pigments, whose color changes between room temperature and 250°C, depending on the nature of the material.

[0008] In addition to thermochromic pigments, other visual differentiating elements can also be added to the coating (EP 2675328, EP 2412846). EP 2319631 describes the development of a two-layer silicone resin-based coating in combination with 0.5-20% of a high-temperature thermoplastic material (base layer), which allows for the production of a coating with high mechanical strength, adhesion to the substrate, and non-stick properties. The nature of the thermoplastic material differs between the base layer (PEEK) and the finishing layer (PPS), and it is primarily located in the base layer to ensure adhesion to the substrate. The patent does not describe a temperature indicator. US Patent Application Publication No. 2022 / 0073785 proposes a two-layer silicone / thermoplastic coating structure in which the thermoplastic material is much more concentrated and does not mention the incorporation of a color indicator based on a thermochromic pigment. Summary of the Invention [Means for solving the problem]

[0009] A first object of the present invention relates to a coated cooking element (1) for a cooking utensil or an electric cooking appliance, the coated cooking element (1) having a metal substrate (2) coated on at least one surface (2a) with at least the following layers, in this order from the metal substrate side: a base layer (3a), one or more intermediate layers (3b), and a finishing layer (3c): The base layer (3a) is made of one or more silicone resins and optionally: one or more thermoplastic polymers, and / or one or more colorants selected from the group consisting of thermochromic pigments, heat-stable pigments, flakes, and mixtures thereof; and / or one or more fillers, and / or One or more additives and consists of; The one or more intermediate layers (3b) comprise one or more colorants selected from the group consisting of thermochromic pigments, heat stable pigments, flakes, and mixtures thereof, 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 and consists of; The finishing layer (3c) is made of 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 Flakes It consists of:

[0010] Another object of the present invention is to provide a method for producing a pharmaceutical composition comprising the following sequential steps: i. providing a metal substrate (2) having a surface (2a); ii. optionally, pretreating the surface (2a) of said metal substrate (2) to be coated; iii. applying a base layer (3a); iv. drying the base layer (3a); v. applying one or more intermediate layers (3b); vi. optionally drying the one or more intermediate layers (3b); vii. applying a finishing layer (3c); The present invention relates to a method for producing a coated cooking element (1) according to the present invention.

[0011] Another object of the present invention relates to a cooking utensil (100) comprising a coated cooking element (1) according to the invention.

[0012] Another object of the invention relates to an electric cooking appliance (200) comprising a coated cooking element (1) according to the invention and a heat source (210) designed to heat said coated cooking element (1). [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 shows a cooking element according to the invention, in which layer (3b) is a continuous layer and covers the entire layer (3a). [Figure 2] FIG. 1 shows 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 shows a cooking element according to the invention, in which layer (3b) consists of two decorations (i) and (j). [Figure 4] 4A and 4B show pattern distributions, where (4A) shows adjacent non-overlapping patterns, (4B) shows partially overlapping patterns, and (4C) shows overlapping patterns. [Figure 5] 1 shows a cooking utensil according to the present invention; [Figure 6] 1 shows an electric cooking appliance according to the present invention; DETAILED DESCRIPTION OF THE INVENTION

[0014] (definition) For the purposes of the present invention, the term "layer" should be understood to mean a continuous layer or a discontinuous layer. A continuous layer (also called a monolithic layer) is a single body that forms an all-solid block that completely covers the surface to which it is applied. A discontinuous layer (or non-monolithic layer) may be composed of several parts and is therefore not a single body.

[0015] The terms "base", "primer layer", "bonding layer" or "bonding primer" are intended to mean all layers, from the first layer applied directly onto the substrate (which preferably adheres well to the substrate and gives the coating all its mechanical properties (hardness, scratch resistance)) to the last layer before the first decorative layer.

[0016] The term "finishing layer" or "finish" is intended to mean a continuous transparent surface layer that allows full visibility of the decorative layer while protecting it from mechanical attack and providing the coating with non-stick properties. Preferably, the final finishing layer is intended to come into contact with food.

[0017] The term "decoration" or "decorative layer" is intended to mean one or more continuous or discontinuous layers comprising a pigment composition. The decoration can 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 at the conventional use distance of the household item.

[0018] The term "overlapping layers" is intended to mean partially or completely superposed layers, which may be in the form of partially overlapping patterns, for example, concentric disks.

[0019] The term "adjacent layers" is intended to mean non-overlapping layers. These layers may be in the form of non-overlapping, identical or different patterns, and are preferably uniformly distributed.

[0020] The term "reference temperature pigment composition" is intended to mean a composition containing a pigment that, at a given temperature, can indicate that an optimum use temperature 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 optimum use temperature is reached either when the colors are identical, or when the colors are visually significantly different.

[0021] A "reference temperature pigment composition" can include a pigment having the following properties: At optimum use temperature, the color is identical to the thermochromic pigment composition: At room temperature, the pigment has the same color as the thermochromic pigment composition at its optimum use temperature and does not change color with temperature; or * At room temperature, the pigment either has a color different from that of the thermochromic pigment composition, and changes to the same color as the thermochromic pigment composition at the optimum use temperature; · Whether or not the pigment changes color with temperature, the color is significantly different from that of the thermochromic pigment composition at its optimum use temperature.

[0022] The optimum use temperature 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 the color indicated on the color scale provided to the user together with the article. Reference temperature pigment compositions are thermochromic or heat stable. For example, the reference temperature pigment composition can be a reference cooking temperature pigment composition or can be intended to indicate the risk of overheating.

[0023] The present invention has at least the following advantages: The coating according to the invention has a highly visible thermochromic function, exhibiting a high contrast color change in a target temperature range, for example around the food cooking temperature of a kitchen appliance; The coating according to the invention provides good temperature control when cooking food, which is necessary not only for health and taste reasons, but also for safety and to prevent 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 due to the action of heat, the compound returns to its original state and color; this color change cycle (reversible) can be repeated indefinitely; The coatings according to the invention have remarkable thermal stability at elevated temperatures, being stable up to about 450°C.

[0024] Within the meaning of the present invention, the term "thermochromic semiconductor" is intended to include inorganic or organic compounds whose color changes reversibly with increasing temperature. The gradual and reversible thermochromic properties of these semiconductor compounds are 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 lattice of anions and cations results in the energy levels being grouped into energy bands. The higher-energy, filled energy band is called the valence band, and the lower-energy, empty energy band is called the conduction band. Between these two bands is a forbidden band, called the band gap. The color of a semiconductor material results from the presence of charge transfer. Charge transfer corresponds to the transition of an electron from the valence band to the conduction band of a given atom, or more commonly, from an anionic orbital to a cationic orbital (interatomic photon absorption).

[0025] In the intended application field of the present invention, the optimum state is achieved when the coating is heated to a temperature suitable for cooking food, preferably 100 to 250°C.

[0026] For the purposes of the present invention, "pigment or thermochromic pigment composition" should be understood to mean a pigment or pigment composition that changes color as a function of temperature over a given temperature range, and this change is reversible. This color change is visible to the user with the naked eye and at customary use distances.

[0027] The term "thermally stable pigment" is understood to mean a pigment that does not exhibit a color change when exposed to an elevated temperature within a given temperature range, or that exhibits a hue change that is so small that it is not visible to the user with the naked eye and at conventional working distances when exposed to an elevated temperature within a given temperature range.

[0028] Preferably, the heat stable pigment has a color difference ΔE between 25°C and 200°C * is less than 10 and ΔE * is the CIE1976 formula in CIELAB color space:

[0029]

number

[0030] (In the formula, L1 * , a1 * and b1 * is the L of the compound at room temperature * a * b * Characterize the value, L2 * , a2 * and b2 * is the L of the compound at 200 °C * a * b * characterize the value)

[0031] The term "color identical" means indistinguishable by a user with the naked eye and at normal viewing distances.

[0032] For the purposes of the present invention, the expression "cookware" is to be understood to mean an object intended for cooking purposes, which for this purpose is intended to be subjected to a heat treatment.

[0033] For the purposes of the present invention, the expression "object intended to undergo a heat treatment" should be understood to mean an object such as a frying pan, a saucepan, a sauté pan, a wok, a barbecue grill, which is heated by an external heating system and is capable of conducting the thermal energy supplied by the external heating system to a material or food in contact with said object.

[0034] For the purposes of the present invention, the expression "electric cooking appliance" should be understood to mean a heating object having its own heating system, such as an electric crepe maker, an electric raclette machine, an electric fondue machine, an electric grill, an electric griddle, an electric cooker, a bread maker, an electric pressure cooker, etc.

[0035] "Coating" is understood to mean a layer that covers a metal substrate and adheres to said substrate.

[0036] "Silicone resin-based coating" is understood to mean a coating that contains one or more silicone resins in one or more layers. Advantageously, the coating according to the present invention obtained is solid. "Solid" is understood to mean the properties of a cohesive material that is insoluble in water, common solvents, food ingredients such as aqueous or fatty mixtures, even if the material is very hard or very flexible, such as an elastomer.

[0037] In the present invention, weight percentages are expressed as dry weight values, i.e., without solvent.

[0038] Description of the Invention The present invention relates to a coated cooking element (1) for a cooking utensil or electric cooking appliance, the coated cooking element (1) having a metal substrate (2) coated on at least one surface (2a) with at least the following layers, in order from the metal substrate side: a base layer (3a), one or more intermediate layers (3b), and a finishing layer (3c): At least the following layers, in the following order: The base layer (3a) is made of one or more silicone resins and optionally: one or more thermoplastic polymers, and / or one or more colorants selected from the group consisting of thermochromic pigments, heat-stable pigments, flakes, and mixtures thereof; and / or one or more fillers, and / or One or more additives and consists of; The one or more intermediate layers (3b) comprise one or more colorants selected from the group consisting of thermochromic pigments, heat stable pigments, flakes, and mixtures thereof, 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 and consists of; The finishing layer (3c) is made of 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 · It is flake. It consists of:

[0039] Advantageously, the layers (3a), (3b) and (3c) form a coating (3) that coats the metal substrate (2). This coating (3) has non-stick properties and forms a non-stick coating. Advantageously, the layer (3a) is in contact with the metal substrate (2) through one face (2a). 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. Advantageously, the top layer (3c) is in contact with the food product through one of its sides, thus forming the cooking surface (5). The coating (3) of the cooking element (1) according to the invention does not contain fluorinated polymers, also called fluoropolymers, in other words, said coating does not contain fluorinated polymers.

[0040] Advantageously, the thickness of the layer (3a) is between 10 and 100 μm, preferably between 20 and 85 μm, particularly preferably between 30 and 70 μm. Advantageously, the thickness of layer (3b) is between 1 μm and 100 μm, preferably between 2 μm and 30 μm, particularly preferably between 3 μm and 10 μm. Advantageously, the thickness of 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. In a particular embodiment of the invention, the thickness of layer (3c) is 100 nm±5 nm. According to one embodiment, the thickness of layer (3c) is between 0.1 and 2 μm, preferably between 0.2 and 1.5 μm. According to another embodiment, the thickness of the layer (3c) is between 10 and 100 μm, preferably between 20 and 85 μm, particularly preferably between 30 and 70 μm.

[0041] (metal substrate) Advantageously, said metal substrate (2) is a substrate made of aluminium, stainless steel, cast iron or cast aluminium, iron, titanium or copper. For the purposes of the present invention, aluminium is understood to mean a metal consisting of 100% aluminium or an aluminium alloy.

[0042] Advantageously, the metal substrate (2) is an aluminum substrate, a stainless steel substrate or a multi-layer metal substrate. The metal substrate (2) may also be a two-layer or three-layer substrate, the multi-layer being obtained, for example, by co-lamination, solid-state bonding or hot or cold impact bonding. Preferably, the metal substrate (2) comprises alternating layers of metals and / or metal alloys.

[0043] According to one embodiment, the metal substrate (2) is an aluminum alloy substrate, a stainless steel substrate, or a multi-layer metal substrate whose surface (2a) is an aluminum alloy or stainless steel. Preferably, the metal substrate (2) is an aluminum substrate. Advantageously, the thickness of the metal substrate (2) is between 0.5 mm and 10 mm.

[0044] Advantageously, the surface (2a) of the metal substrate (2) may be previously subjected to a surface treatment to improve the adhesion of the coating to the substrate. According to one embodiment, the surface of face (2a) of the metal substrate (2) is subjected to a surface treatment, which may be chemical etching, brushing, hydration, sandblasting, shot peening, physicochemical plasma, corona or laser treatment, chemical activation or a combination of these different techniques. 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 (forming tubular alumina structures), chemical etching, sandblasting, brushing, shot peening or by adding material by techniques such as thermal spraying (flame, plasma, arc spraying). Other metal substrates can also be subjected to the addition of material by techniques such as grinding, sandblasting, brushing, microbead blasting or thermal spraying (flame, plasma, arc spraying).

[0045] Metal substrates that can be used advantageously in the present invention include anodized or non-anodized aluminum substrates (optionally polished, brushed, sandblasted, shot peened or microbead blasted), anodized or non-anodized aluminum alloy substrates (optionally polished, brushed, sandblasted or microbead blasted), steel substrates (optionally polished, brushed, sandblasted, shot peened or microbead blasted), stainless steel substrates (optionally polished, brushed, shot peened or microbead blasted), cast steel, aluminum or iron substrates, optionally hammered or polished copper substrates,

[0046] Advantageously, the substrate can be selected from substrates comprising ferritic stainless steel / aluminum / austenitic stainless steel layers, substrates comprising stainless steel / aluminum / copper / aluminum / austenitic stainless steel layers, cast aluminum, aluminum or aluminum alloy calottes lined with an outer stainless steel bottom, metal co-laminate substrates (for example, two-layer co-laminate substrates comprising a stainless steel layer (for example, intended to constitute the inner surface of the article) and an anodized or non-anodized layer of aluminum or aluminum alloy (intended to constitute the outer surface of the article)).

[0047] Advantageously, the arithmetic mean roughness Ra of the surface of the face (2a) of the metal substrate (2) is 1 μm or more. The arithmetic mean roughness Ra is measured with a profilometer according to ISO 4287. Ra is the arithmetic mean of deviations from the mean. In particular, the surface profile can be investigated using a profilometer with a probe equipped with a fine stylus with a diamond tip, or an optical measuring device such as Altisurf®, which allows contactless measurements with a confocal chromatic sensor. This investigation of the surface profile makes it possible to define the mean arithmetic roughness Ra.

[0048] (silicone resin) In this specification, the term "silicone resin" is used interchangeably to refer to silicone before or after crosslinking. In this specification, the term "silicone" refers to an organopolysiloxane material. Crosslinking is a process that converts silicone into an insoluble material, for example, by polyaddition, polycondensation, or dehydrogenation. Crosslinking is generally carried out using a precursor, which is a silicone oil or resin, and crosslinks to obtain a three-dimensional network and form a material referred to herein as a silicone resin. This crosslinking can be achieved by thermal activation or chemical activation using a catalyst such as platinum.

[0049] Silicone resins can be obtained from precursors. Advantageously, the precursors are soluble in solvents or aqueous emulsions, such as crosslinkable oils or resins. In particular, the precursors are 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 (e.g., methoxy or ethoxy); and / or silicone resins or silicone-polyester resins (copolymers) containing at least one alkoxy group (especially ethoxy or hydroxyl groups), and mixtures thereof. These precursors can be crosslinked to obtain silicone resins that are insoluble and substantially solid.

[0050] Advantageously, these precursors are polymers or oligomers. The polymers or oligomers may be in the form of silicone oils with various degrees of branching; or silicone resins with various degrees of pre-crosslinking or copolymers of silicone resins, such as silicone-polyester, silicone-alkyd, silicone-polyurethane, or silicone-epoxy resin; or mixtures of silicone oils, silicone resins, and copolymers of silicone resins. The silicon atoms may be substituted with alkyl groups (especially methyl groups) or aryl groups (especially phenyl groups), or mixtures thereof. Preferably, the oils or resins contain one or more (2, 3, or more) hydroxy or alkoxy functional groups (especially methoxy, ethoxy, butoxy) as substituents on the silicon atoms.

[0051] Advantageously, the silicone resin obtained after crosslinking of its precursor, i.e. crosslinked, is selected from the group consisting of methylsilicone resins and / or phenylsilicone resins and / or methylphenylsilicone resins, methylsilicone-polyester resins (copolymers), phenylsilicone-polyester resins (copolymers), methylphenylsilicone-polyester resins (copolymers), silicone-alkyd resins (copolymers), modified silicone resins and mixtures thereof.

[0052] Advantageously, the silicone resin is selected from the group consisting of methylsilicone resins and / or phenylsilicone resins and / or methylphenylsilicone resins, methylsilicone-polyester resins (copolymers), phenylsilicone-polyester resins (copolymers), methylphenylsilicone-polyester resins (copolymers), silicone-alkyd resins (copolymers), modified silicone resins and mixtures thereof.

[0053] The silicone resin of the single layer (3) forms a network that can consist of a combination of four simple 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.

[0054] [Table 1]

[0055] Organopolysiloxane materials or polymers are obtained by crosslinking precursors, which can be monomers, polymers, or intermediate oligomers. Organopolysiloxane polymers can also be obtained from mixtures of these different precursors. The crosslink density increases 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 units within the precursor. The polymer precursors are organopolysiloxanes. These polymers 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 R groups can be present on the same polymer. Organopolysiloxanes can be linear or slightly branched (predominantly D groups) or branched or highly branched (predominantly T and Q groups). Linear or slightly branched organopolysiloxanes are generally liquids with some viscosity at room temperature and are called silicone oils. Branched or highly branched (pre-crosslinked) organopolysiloxanes form networks on the scale of independent macromolecules and are called silicone resins. At room temperature, the resins are substantially solid or liquid, and are solutions in solvents or aqueous emulsions, especially when the molecular weight is quite low. They can be copolymerized with silicon-free organic polymers or oligomers. The silicon-free organic polymers or oligomers are selected from polyester, acrylic, alkyd, polyurethane, and epoxy resins, among others.

[0056] When crosslinking is by hydrolysis-polycondensation, the crosslinking is effected by means of reactive hydroxy or alkoxy functional groups, particularly methoxy, ethoxy or butoxy, present on the organopolysiloxane. When crosslinking is by polyaddition (or hydrosilylation), it is achieved by reaction of reactive vinyl functional groups (-CH=CH) present on one organopolysiloxane with reactive silylhydride functional groups (Si-H) present on the other organopolysiloxane that is mixed first. All of these reactive functional groups are present in at least one quantity on each organopolysiloxane, and may be present in two, three, or more quantities, 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 either at the end of the polymer chain or distributed along the chain.

[0057] In particular, the silicone-polyester resin has a silicone / polyester weight ratio of, for example, between 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.

[0058] Linear PDMS silicone oils, either pure or pre-emulsified in water, are primarily characterized by their molecular weight (which is a directly proportional increasing function of the viscosity of the pure oil). Linear PDMS silicone oils are then characterized by the presence, number, and location on the molecular chain of reactive functional groups (e.g., hydroxyl functional groups (silanol) on silicon atoms). For example, reactive oils with viscosities of 50 to 20,000 MPa·s, especially 300 to 5,000 MPa·s, can be used. The reactive oils have at least one reactive functional group, preferably at least two, located at the chain ends.

[0059] Polymer precursors that react by polyaddition include, for example, polymethylhydrosiloxanes, vinylmethylsiloxanes, vinyl-terminated polydimethylsiloxanes (PDMS), especially linear vinyl-terminated diphenylsiloxane-dimethylsiloxane copolymers, hydride-terminated polydimethylsiloxanes, hydride-terminated polyphenylmethylsiloxanes, cyclic vinylmethylsiloxanes, vinyl-MQ resins, trimethylsilyl-terminated polymethylhydrosiloxanes, copolymers of methylhydrosiloxane and dimethylsiloxane terminated with trimethylsiloxane, MQ resin hydrides, and the like, and combinations thereof.

[0060] Polymer precursors that react by hydrolysis-polycondensation, whether silicone resins or silicone oils, 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), copolymers of silanol-terminated diphenylsiloxane and dimethylsiloxane, poly(2-acetoxyethylsilsesquioxane), organically modified alkoxysilanes and their oligomers, and all similar polymers, as well as mixtures thereof.

[0061] Similarly, organopolysiloxane materials or polymers can 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 linear, branched, or cyclic oligomeric precursors. These oligomeric precursors have a lower molecular weight than the polymer precursors. To promote a high crosslink density in the final organopolysiloxane polymer, polymeric and / or oligomeric precursors, as described above, having a number of reactive functional groups greater than two, advantageously much greater than two, can be added to the mixture as a "co-binder."

[0062] To obtain a solid organopolysiloxane polymer that is combined with the thermoplastic material of each layer, monomers, oligomers and / or polymer precursors, in particular silicone resins copolymerized with organic polymers or silicone resins not copolymerized with organic polymers, act as polymer binders.

[0063] When added in small amounts (typically 0.1-5% dry) to the overall layer formulation, silicone oil-type organopolysiloxane precursors can be considered additives, independent of other components for the formation of solid organopolysiloxane polymers.

[0064] 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 platinum, tin, zinc, zirconium and cerium, in particular platinum-cyclovinylmethylsiloxane complexes, tin ethylhexanoate, zinc ethylhexanoate, zirconium ethylhexanoate, cerium ethylhexanoate and dibutyltin laurate. When crosslinking organopolysiloxanes by hydrosilylation, the addition of a catalyst may be necessary, such as platinum or a suitable platinum-based catalyst, such as Karstedt's catalyst or Ashby's catalyst.

[0065] For example, a cross-linking agent having a Si-H bond may be present.

[0066] According to one embodiment, the proportion of silicone resin in layer (3a) is equal to or greater than 20% by weight relative to the total weight of each layer (3a). According to another embodiment, the proportion of silicone resin in layer (3a) is equal to or greater than 40% by weight relative to the total weight of each layer (3a). According to yet another embodiment, the proportion of silicone resin in layer (3a) is equal to or greater than 50% by weight relative to the total weight of each layer (3a). According to one embodiment, the proportion of silicone resin in layer (3b) is equal to or greater than 20% by weight relative to the total weight of each layer (3b). According to another embodiment, the proportion of silicone resin in the layer (3b) is equal to or greater than 40% by weight, respectively, relative to the total weight of the layer (3b). According to yet another embodiment, the proportion of silicone resin in layer (3b) is equal to or greater than 50% by weight relative to the total weight of each of layers (3b). According to one embodiment, the proportion of silicone resin in layer (3c) is equal to or greater than 20% by weight relative to the total weight of each layer (3c). According to another embodiment, the proportion of silicone resin in layer (3c) is equal to or greater than 40% by weight relative to the total weight of each of layers (3c). According to yet another embodiment, the proportion of silicone resin in layer (3c) is equal to or greater than 50% by weight relative to the total weight of each layer (3c).

[0067] (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.

[0068] (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), and in a particularly preferred embodiment is PEEK.

[0069] (Other aromatic thermoplastic polymers) Suitable examples of aromatic thermoplastic polymers according to the present invention include poly(phenylene oxide) (PPO), poly(aryl ether sulfone) polymers (PAES), in particular polyether sulfone (PES), polyphenylene ether sulfone (PPSU), poly(arylene sulfide) (PAS), in particular polyphenylene sulfide (PPS), liquid crystal polymers and mixtures thereof.

[0070] (Heterocyclic Thermoplastic Polymer) Suitable examples of heterocyclic thermoplastic polymers according to the present invention include polyetherimide (PEI), polyimide (PI), polyamideimide (PAI), polybenzimidazole (PBI), or mixtures thereof.

[0071] 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), and polyetherketoneetherketoneketone (PEKEKK), and mixtures thereof.

[0072] According to one variant, the PAEK is used in the form of a suspension, the PAEK particles in the PAEK suspension having a particle size d50 of approximately 10 μm to 15 μm.

[0073] Advantageously, the nature of the thermoplastic polymer(s) in layers (3a), (3b) and (3c) may be the same or different.

[0074] Advantageously, layer (3a) comprises one or more thermoplastic polymers, preferably less than 50% by weight of said layer, more preferably less than 40% by weight of said layer, of one or more thermoplastic polymers. Advantageously, layer (3b) comprises one or more thermoplastic polymers, preferably less than 30% by weight of said layer, more preferably less than 20% by weight of said layer, of one or more thermoplastic polymers. Advantageously, layer (3c) comprises one or more thermoplastic polymers, preferably less than 50% by weight of said layer, more preferably less than 40% by weight of said layer, of one or more thermoplastic polymers.

[0075] According to one embodiment, layers (3a) and (3c) comprise one or more thermoplastic polymers, and preferably the proportion of thermoplastic polymer in layer (3c) is greater than the proportion of thermoplastic polymer in layer (3a). According to another embodiment, layers (3a) and (3c) comprise one or more thermoplastic polymers, the proportion of thermoplastic polymer in layer (3a) being greater than the proportion of thermoplastic polymer in layer (3c).

[0076] (filling material) Fillers for the purposes of the present invention can improve the mechanical strength and thermal conductivity of the coating while providing mechanical reinforcement and also imparting hydrophobic properties. The filler does not have the sole function of imparting color to the coating, although it may contribute thereto. The presence of fillers with good thermal conductivity can compensate for the low thermal conductivity of PAEK polymers

[0077] Advantageously, the filler or fillers are selected from the group consisting of ceramic fillers (such as SiO2), and / or inorganic and / or metallic fillers (such as Al2O3, TiO2), and / or silica fillers, and / or diamond particle fillers.

[0078] Preferably, the one or more fillers are selected from the group consisting of metal oxides, metal carbides, metal oxynitrides, metal nitrides, and mixtures thereof. Advantageously, said metal is a transition metal, such as at least one element chosen from B, Ni, Ti, Zr or Hf.

[0079] More preferably, the one or more fillers are selected from the group consisting of: Reinforcing fillers: organic or inorganic hard fillers; the inorganic hard fillers are preferably particles of silicon carbide, or alumina, or zirconia, or graphite, or ceramic, or carbonate, or alumina hydrate, aluminum trihydroxide, or one or more metal oxides, graphite, graphene; · Other reinforcing fillers selected from metal oxides: silica, mica, lamellar fillers, montmorillonite, sepiolite, gypsum, kaolinite and laponite, zinc dioxide, quartz, zirconium phosphate, alumina, zirconia, zinc oxide, copper oxide, and iron oxide; · Filler material selected from reinforcing fibers: glass fiber, carbon fiber, aramid fiber; Conductive fillers consisting of 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, such as cubic boron nitride, diamond particles, metal particles; · Lamellar fillers such as clay, graphene and graphite that can impart lubricating properties.

[0080] 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 a maximum of 60% by weight; · Alumina, alumina hydrate, aluminum trihydroxide; d50 less than 0.1 μm and 30 m 2 / g or more, preferably 30 to 500m 2 / g BET specific surface area of silica (precipitated silica or pyrogenic silica); or · Quartz and silica mixtures, diatomaceous earth or crushed quartz, titanium dioxide, mica, talc, kaolin, barium sulfate, hydrated lime, zinc oxide, expanded vermiculite, unexpanded vermiculite, calcium carbonate, etc.

[0081] More preferably, the one or more fillers are selected from the group consisting of alumina, silicon carbide, tungsten carbide, boron nitride, quartz, and mixtures thereof.

[0082] Advantageously, the median diameter d50 of the filler is between 0.1 and 50 μm, more advantageously between 5 and 15 μm.

[0083] Advantageously, the proportion of filler in the layer is comprised between 0.5 and 30% by dry weight, preferably between 5 and 20%, relative to the total weight of said layer after hardening. Advantageously, the proportion of filler in layer (3a) is less than 10% by weight relative to the total weight of said layer. Advantageously, the proportion of filler in layer (3b) is less than 10% by weight relative to the total weight of said layer. Advantageously, the proportion of filler in layer (3c) is less than 10% by weight relative to the total weight of said layer. Advantageously, the proportion of filler in layers (3a), (3b) and (3c) is less than 10% by weight relative to the total weight of each of layers (3a) / (3b) / (3c). Advantageously, the proportions of filler in layers (3a), (3b) and (3c) may be the same or different.

[0084] Advantageously, the nature of the filler in layers (3a), (3b) and (3c) may be the same or different.

[0085] (additives) Advantageously, said additives are selected from the group consisting of antifoaming agents, dispersants, wetting agents, thickeners, pH adjusters and reactive silicone oils.

[0086] The one or more antifoaming agents are preferably selected from the group consisting of mineral oils, diols, hydrocarbons, glycerides, oxiranes and emulsifying fatty acids.

[0087] The one or more surfactants are preferably selected from the group consisting of glycol ethers, ethoxylated alcohols excluding alkylphenol ethoxylates (APEs), and gemini surfactants.

[0088] The dispersant(s) are preferably selected from the group consisting of anionic dispersants such as fatty acid derivatives.

[0089] The thickener is preferably selected from the group consisting of acrylic or polyurethane copolymers, cellulose and pyrogenic silica.

[0090] The pH adjuster is preferably selected from the group consisting of Bronsted bases: ammonia, amines (such as triethylamine and triethanolamine), hydroxides (such as sodium hydroxide and potassium hydroxide), and carbonates.

[0091] Advantageously, the proportion of additives in layer (3a) is less than 20% by weight relative to the total weight of said layer. Advantageously, the proportion of additives in layer (3b) is less than 20% by weight relative to the total weight of said layer. Advantageously, the proportion of additives in layer (3c) is less than 20% by weight relative to the total weight of said layer. 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).

[0092] (coloring agent) Advantageously, the colorant is selected from the group consisting of thermochromic pigments, heat stable pigments, flakes, and mixtures thereof.

[0093] Advantageously, the proportion of colorant in the layer is between 0.5% and 50% by dry weight relative to the total weight of said layer after curing. Advantageously, the proportion of colorant in layer (3a), if present, ranges from 10% to 40% by weight relative to the total weight of said layer. Advantageously, the proportion of colorant in layer (3b) ranges from 10% to 40% by weight relative to the total weight of said layer. Advantageously, the proportion of colorant in layer (3c), if present, is less than 10% by weight relative to the total weight of said layer. Advantageously, the proportions of colorants in layers (3a), (3b) and (3c) may be the same or different.

[0094] Advantageously, the nature of the colorants in layers (3a), (3b) and (3c) may be the same or different.

[0095] (thermochromic pigment) Preferably, the thermochromic pigment is Bi2O3, Fe2O3, V2O5, WO3, CeO2, In2O3, Y 1.84 Ca 0.16 Ti 1.84 V 0.16 O 1.84 , AgI, (Bi 1-x A x )(V 1-y M y )O4(in the formula: x is equal to 0 or x is between 0.001 and 0.999; y is equal to 0 or 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) is selected from the group consisting of:

[0096] If A and M are known to be distinct from each other, then: 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, and Ba; M is an alkaline earth metal and can be selected from Be, Mg, Ca, Sr, and Ba; A is a transition metal and may be selected from Sc, Ti, Cr, 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, Ti, Cr, 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, Sn; M is a poor metal and can be selected from Al, Zn, Ga, In, Sn; A is a metalloid and can be selected from B, Si, Ge, Sb; M is a metalloid and can be selected from B, Si, Ge, Sb; A is a lanthanide and may 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.

[0097] Preferably, A and M, which are different from each other, are B and / or Mg.

[0098] Preferably, (Bi 1-x A x )(V 1-y M y )O4 pigment has a monoclinic scheelite crystal morphology at room temperature. Preferably, x and y are equal to 0, i.e., (Bi 1-x A x )(V 1-y M y The )O4 pigment is bismuth vanadate (BiVO4). Advantageously, BiVO4 is used which has a monoclinic scheelite crystal structure at room temperature. Bismuth vanadate, a yellow inorganic compound with the formula BiVO4, is widely used due to its coloring properties and non-toxicity. It is listed in the Color Index International database as QI Pigment Yellow 184 and is sold by Heubach (Vanadur®), BASF (Sicopal®), FERRO (Lysopac), and Bruchsaler Farbenfabrik (Brufasol®), among others.

[0099] (heat stable pigment) Preferably, the heat-stable pigment is from the following group: Titanium rutile yellow pigment; Yellow pigments derived from bismuth, such as stabilized bismuth vanadate (Py 184 ) selected from; red pigments, such as perylene red (e.g. PR149, PR178 and PR224), selected from 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 ;PO 78 ); Chromium-Antimony-Titanium Rutile Orange Yellow Pigment (PBr 24 ); Zinc tin rutile orange yellow pigment (Py 216 ); Zinc tin sulfide and 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 is selected from.

[0100] (flake) 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 provide specific color effects. Advantageously, the flakes are particles selected from the group consisting of mica, aluminium, titanium dioxide coated mica, or mixtures thereof.

[0101] (Holographic Flakes) Advantageously, the flakes are holographic flakes, ie a mixture of magnetizable and non-magnetizable particles.

[0102] Advantageously, the magnetizable particles can be particles containing at least one ferromagnetic metal. These magnetizable particles can be of homogeneous nature, i.e., made of the same material, or of composite nature, i.e., they have a core-shell structure, with the ferromagnetic metal located in the core and / or shell of the particles. Examples of composite magnetizable particles include mica flakes coated with iron oxide Fe2O3, stainless steel fibers coated with a sol-gel material as protection against corrosion during the coating process, or flakes made of plastic material coated with iron oxide Fe2O3, or flakes whose core is made of a ferromagnetic metal and whose shell is made of a plastic material or a sol-gel material.

[0103] According to one embodiment, some of the magnetizable particles are oriented to form a three-dimensional decoration.

[0104] Advantageously, the mixture of magnetizable and non-magnetizable particles represents between 1% and 5% by weight of the layer weight, preferably between 2% and 3% by weight. 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.

[0105] Advantageously, the magnetizable particles have a dimension D50 of less than or equal to 23 μm. For the purposes of the present invention, the term "D50" is understood to mean the largest dimension exhibited by 50% of the particles by number.

[0106] Advantageously, the non-magnetizable particles have a dimension D90 comprised between 20% and 250% of the dimension D90 of the magnetizable particles. For the purposes of the present invention, the term "D90" is understood to mean the largest dimension exhibited by 90% of the particles by number.

[0107] Advantageously, the magnetizable and / or non-magnetizable particles are colored on the surface. Advantageously, the non-magnetizable particles consist of mica, aluminium or mica coated with titanium dioxide. Advantageously, the magnetizable particles consist of iron, iron oxide, iron-coated aluminium or iron-coated mica, the iron being in the ferrite form.

[0108] (Decoration) According to one embodiment, the layer or layers (3b) are continuous and cover the entire layer (3a) (see Figure 1). According to another embodiment, the layer or layers (3b) are discontinuous and do not cover the entire layer (3a) but form at least one decoration (see FIG. 2).

[0109] Advantageously, one or more layers (3b) form multiple decorations, one (i) comprising one or more thermochromic pigments and the other (j) comprising at least one reference temperature pigment composition (see Figure 3). 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 evenly distributed over the entire surface and alternating with respect to each other (see FIG. 4A). According to another embodiment, the two decorations (i) and (j) are partially overlapping, for example each decoration is represented by a different geometric pattern that is uniformly distributed over the entire surface and that partially overlaps (see FIG. 4B). Preferably, the two decorations (i) and (j) are overlapping, either because one of the two decorations is a continuous layer and the other decoration covers it in the form of a pattern, or because the two decorations (i) and (j) are in the form of overlapping patterns (see Figure 4C).

[0110] (method) The present invention also relates to a method for manufacturing the coated cooking element (1) according to the invention, said method comprising the following successive steps: i. providing a metal substrate (2) having a surface (2a); ii. optionally, pretreating the surface (2a) of said metal substrate (2) to be coated; iii. applying a base layer (3a); iv. drying the base layer (3a); v. applying one or more intermediate layers (3b); vi. optionally drying the one or more intermediate layers (3b); vii. applying a finishing layer (3c); Includes:

[0111] Advantageously, the steps of the method according to the invention make it possible to coat a metal substrate (2) with a coating (3) formed from three layers (3a), (3b) and (3c). Generally, these three layers are wet at the time of application. For the purposes of the present invention, "wet layer" is understood to mean that the layer contains all or part of its solvent.

[0112] Preferably, all or part of the solvent in the wet layer is removed naturally or by physical treatment such as heat drying, air drying, vacuum treatment.

[0113] Advantageously, the coating composition according to the invention can also comprise at least one solvent. Advantageously, the solvent can be protic. Advantageously, the solvent can be non-toxic. Advantageously, the solvent that can be used in the coating composition according to the invention can comprise at least one alcohol, preferably chosen from isopropanol, methanol, ethanol and mixtures thereof.

[0114] The application of the coating can be carried out in several layers. In this case, the deposition of at least one layer of the coating (3) according to the invention is repeated several times on at least one of the two opposite faces of the substrate. Preferably, a drying step is carried out between the application of each layer, and after the application of the last layer, the coated substrate is cured. The application of the coating (3) according to the method of the invention to the substrate (2) makes it possible to obtain a layer of a heat-stable coating.

[0115] The coating formulation applied 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.

[0116] Advantageously, the method for producing the coated cooking element (1) according to the invention comprises, after the application of each layer, one or more drying steps between 80 and 150° C. Drying can be carried out by convection or infrared radiation.

[0117] The method according to the invention allows the application of the coating according to the invention to flat substrates, to shaped substrates, or to locally flat areas of shaped substrates. A heat-stable coating layer is obtained. This coating layer is generally wet.

[0118] Advantageously, the method for producing the coated cooking element (1) according to the invention comprises a step of shaping said substrate (2) before step iii, after step iv and after curing step vii. Shaping is also called stamping.

[0119] If there is a step iii. of applying a coating before the molding step, the coating is preferably applied by spraying. If the molding step is followed by step iii. of applying a coating, the coating is preferably carried out by screen printing or roll printing.

[0120] Advantageously, the method according to the invention comprises a step viii. of curing the part obtained in step vii. of the method. For the purposes of the present invention, "curing of the coated substrate" is intended to mean a heat treatment that makes it possible to densify the coating layer or layers applied to the substrate and that crosslinks the organopolysiloxane precursor (silicone resin).

[0121] The present invention also relates to a method for manufacturing a coated cooking element (1) according to the invention, said method comprising the following successive steps: i. providing a metal substrate (2) having a surface (2a); ii. optionally, pretreating the surface (2a) of said metal substrate (2) to be coated; iii. applying a base layer (3a); iv. drying the base layer (3a); v. applying one or more intermediate layers (3b); vi. optionally drying the one or more intermediate layers (3b); vii. applying a finishing layer (3c); viii. hardening the part obtained in step vii.; Includes:

[0122] Curing is carried out in step viii. Generally, the curing temperature in step viii. is between 230°C and 420°C.

[0123] Advantageously, the method for manufacturing the coated cooking element (1) according to the present invention includes a single final curing step (viii) for curing all of the applied layers. This single curing step is carried out simultaneously for all of the applied layers. This embodiment allows all layers to be deposited, fused, and crosslinked together to form one layer.

[0124] Steps (iii) and (vii) can be carried out by electrostatic powder coating, spraying of a solvent or aqueous phase, screen printing, roll printing, or digital printing. Step (v) can be carried out by pad printing, screen printing, or flexographic printing.

[0125] For the purposes of the present invention, "curing of a coated substrate" is intended to mean a heat treatment that makes it possible to densify one or more coating layers applied to a substrate and also crosslinks the organopolysiloxane precursor (silicone resin).

[0126] Advantageously, the method for producing the coated cooking element (1) according to the invention comprises a step of shaping said substrate (2) before or after step iii. Shaping is also called stamping.

[0127] (Preferred configuration) According to one embodiment, the present invention relates to a coated cooking element (1) for a cooking utensil or electric cooking appliance, the coated cooking element (1) having a metal substrate (2) coated on at least one side (2a) of which the surface (2a) is coated with the following three layers superimposed in the following order from the metal substrate side: (3a) one or more silicone resins, and optionally: one or more thermoplastic polymers, and / or one or more colorants selected from the group consisting of thermochromic pigments, heat-stable pigments, flakes, and mixtures thereof; and / or one or more fillers, and / or one or more additives a base layer consisting of; (3b) one or more colorants selected from the group consisting of thermochromic pigments, heat stable pigments, flakes, and mixtures thereof, 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 and one or more intermediate layers consisting of: (3c) 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 A finishing layer consisting of It is coated with

[0128] According to one embodiment, the base layer (3a) consists of one or more silicone resins and, optionally, one or more thermoplastic polymers.

[0129] According to another embodiment, the base layer (3a) is made of one or more silicone resins and, optionally: one or more colorants selected from the group consisting of thermochromic pigments, heat-stable pigments, flakes, and mixtures thereof; and / or one or more fillers, and / or One or more additives It consists of:

[0130] According to one embodiment, the base layer (3a) consists of one or more silicone resins and one or more thermoplastic polymers. According to one embodiment, the base layer (3a) and the finishing layer (3c) consist of one or more silicone resins and, optionally, one or more thermoplastic polymers. According to one embodiment, the base layer (3a) and the finishing layer (3c) consist of one or more silicone resins and one or more thermoplastic polymers. In these embodiments, advantageously, the one or more thermoplastic polymers are chosen from polyamideimides (PAI), polyimides (PI), polyetherimides (PEI), polybenzimidazoles (PBI), polyethersulfones (PES), polyphenylene ether sulfones (PPSU), polyaryletherketones (PAEK), and mixtures thereof.

[0131] Preferably, the colorants of the one or more intermediate layers (3b) comprise pigments and / or flakes, advantageously holographic flakes.

[0132] According to an alternative embodiment, the intermediate layer or layers (3b) are: one or more colorants, in particular pigments and / or flakes, advantageously holographic flakes; Advantageously, with one or more thermoplastic polymers chosen from polyamideimides (PAI), polyimides (PI), polyetherimides (PEI), polybenzimidazoles (PBI), polyethersulfones (PES), polyphenylene ether sulfones (PPSU), polyaryletherketones (PAEK), and mixtures thereof; · With 0-10% filler; · With 0-20% additives; Optionally, one or more silicone resins It consists of:

[0133] According to another alternative, the intermediate layer or layers (3b) are: one or more colorants, in particular pigments and / or flakes, advantageously holographic flakes; · With 0-10% filler; · With 0-20% additives; one or more silicone resins; Optionally and advantageously, with one or more thermoplastic polymers chosen from polyamideimide (PAI), polyimide (PI), polyetherimide (PEI), polybenzimidazole (PBI), polyethersulfone (PES), polyphenylene ether sulfone (PPSU), polyaryletherketone (PAEK), and mixtures thereof; It consists of:

[0134] According to a particular alternative, the intermediate layer or layers (3b) do not comprise a silicone resin.

[0135] According to another particular alternative, the intermediate layer or layers (3b) are: one or more colorants, in particular pigments and / or flakes, advantageously holographic flakes; Advantageously, one or more thermoplastic polymers chosen from polyamideimides (PAI), polyimides (PI), polyetherimides (PEI), polybenzimidazoles (PBI), polyethersulfones (PES), polyphenylene ether sulfones (PPSU), polyaryletherketones (PAEK), and mixtures thereof; · With 0-10% filler; · With 0-20% additives; One or more silicone resins It consists of:

[0136] 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 a plurality of decorations, one (i) comprising one or more thermochromic pigments and the other (j) comprising at least one reference temperature pigment composition.

[0137] Typically, the thickness of the assembly of one or more intermediate layers (3b) is between 3 and 10 μm.

[0138] Preferably, the intermediate layer or layers (3b) only cover a portion of the base layer (3a).

[0139] According to one embodiment, the finishing layer (3c) consists of one or more silicone resins and, optionally and advantageously, one or more thermoplastic polymers chosen from polyamideimides (PAI), polyimides (PI), polyetherimides (PEI), polybenzimidazoles (PBI), polyethersulfones (PES), polyphenylene ether sulfones (PPSU), polyaryletherketones (PAEK), and mixtures thereof.

[0140] Typically, the thickness of layer (3c) is between 0.1 and 10 μm.

[0141] In certain embodiments, the thickness of layer (3a) is between 30 μm and 70 μm, the thickness of one or more layers (3b) is between 3 μm and 10 μm, and the thickness of layer (3c) is between 0.1 μm and 10 μm.

[0142] (Goods) The present invention also relates to a cooking utensil (100) that includes the coated cooking element (1). According to one embodiment, the cooking utensil (100) has a heating surface (6) intended to be in contact with an external heat source, the heating surface (6) being opposite a cooking surface (5) intended to be in contact with food during cooking. Advantageously, the cookware (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 broiler, a casserole, a cooker or bread maker container, or a serving mold.

[0143] 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 the coated cooking element (1). Advantageously, the electric cooking appliance (200) is selected from the group consisting of an electric crepe maker, an electric raclette machine, an electric fondue machine, 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.

[0144] The 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 the face through which food is introduced into the article or to be placed on the article, and the other face of the substrate is an outer face (optionally convex) intended to be placed towards a heat source. Non-limiting examples of cookware according to the present invention include cookware such as pots and pans, woks and sauté pans, stew pots and casseroles, crepe makers, baking molds and dishes, barbecue plates and grills, cooking bowls, among others. [Example]

[0145] The objects, aspects and advantages of the present invention will be better understood from the following description of particular embodiments thereof, given as non-limiting examples. Of course, the invention is in no way limited to the embodiments described and shown solely by way of example: modifications are possible, particularly in terms of the arrangement of the various elements or by the substitution of technical equivalents, without exceeding the scope of protection of the invention.

[0146] 1) Exemplary Embodiment: <Metal substrate> This is an aluminum substrate that has been sandblasted or shot peened and then subjected to a surface treatment suitable for removing organic contaminants.

[0147] <Ingredients> <Silicone resin> RS1: Ethoxy-functionalized polyester silicone resin in solvent phase (80% silicone / 20% polyester) with a viscosity of approximately 2000 mPa·s at 25°C and a solids content of 75%. · RS2: Ethoxy-functionalized polyester silicone resin in solvent phase (50% silicone / 50% polyester) with a viscosity of approximately 2000 mPa·s at 25°C and a solids content of 75%. · RS3: Ethoxy-functionalized polyester silicone resin in solvent phase (30% silicone / 70% polyester) with a viscosity of approximately 2000 mPa·s at 25°C and a solids content of 75%. RS4: A methylphenyl-functionalized polyester silicone resin in solvent phase with a viscosity of approximately 2000 mPa·s at 25°C and a solids content of 75%. · RS5: A methoxy-functionalized polyester silicone resin in solvent phase (50% silicone / 50% polyester) with a viscosity of approximately 2000 mPa·s at 25°C and a solids content of 75%. · RS6: Ethoxy-functionalized methyl organopolysiloxane resin in aqueous emulsion with a viscosity of approximately 1500 mPa·s at 25°C and a solids content of 52%.

[0148] <Heterocyclic polymer resin> · TORLON, manufactured by SOLVAY, a polyamide-imide (PAI) resin containing 29% dry extractables in N-butylpyrrolidone (NBP).

[0149] <Other aromatic polymer resins> Powdered polyetheretherketone (PEEK), VICOTE 703 from VICTREX, a powdered polymer with a particle size d50 of 25 μm. Powdered polyetheretherketone (PEEK), VICOTE 704 from VICTREX, a powdered polymer with a particle size d50 of 10 μm. Powdered PEEK resin, KEPTSAN 7002 PT from Arkema, d50=20μm. Powdered PEEK resin, KEPTSAN 6002 PT from Arkema, d50=50μm. Powdered polyethersulfone (PES) resin, finely divided grade from SOLVAY, polymer powder with a d50 of 40 μm.

[0150] <Alcohol solvent> Dipropylene glycol butyl ether (DPNB). · 2-Methoxy-1-methylethyl acetate (MPA). · Butyl glycol acetate (BGA). Butyl acetate.

[0151] <Surfactants and antifoaming agents> Mineral oil: Tego foamex K7 from Evonik. Aliphatic alcohol polyglycol ether: Clariant Genapol X080 or Tergitole TMN-100X.

[0152] <Reinforcing filler> Pyrogenic silica: Levasil CC301. Dimethyldichlorosilane treated fumed silica: Aerosil R972.

[0153] <Pigments> Mica: IRIODIN 100 or IRIODIN 300 and / or Magnapearl 5000. Cr / Fe oxide: Sicopal black K0098FK. Carbon black: Derussol F25 or Cabot Monarch 4750. · Perylene red: Paliogen red (PR178). Iron(III) oxide: H856 brick.

[0154] <Acrylic resin> · Rohagit SD 15: 30% solution of acrylic polymer in water phase.

[0155] <Silicone oil> Polyether modified polysiloxane: TEGO GLIDE 100. · Polydimethylsiloxane oil: CT 601M.

[0156] <Other additives> · AMP 90: Solution of 2-amino-2-methyl-1-propanol: 90% in aqueous phase, buffer. · Metolat 368: Fatty acid ester. Dolfynox 1030: Propoxylated polyglycol ether, wetting agent, Edaplan LA 451: anionic ester in ethanol / water, wetting agent · Tego Glide 407: Methylphenylpolysiloxane, flow agent.

[0157] (Operating principle of ball mill (mechanical grinder)) Ball milling involves loading the sample to be ground and so-called grinding balls into a jar and rotating the jar around its axis at a constant speed. Typically, the jar is rotated by a roller device. The sample can be ground dry or dispersed in a suitable solvent (such as water or alcohol). The dispersion may also contain certain auxiliary agents (such as dispersants or antifoaming agents).

[0158] 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, occupies approximately 50-60% of the internal volume of the jar. Advantageously, the different sizes of balls are 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 smallest balls have a size between 2 mm and 10 mm. Alumina and stabilized zirconia are commonly used as ball materials.

[0159] (2) Examples of cooking implements according to the present invention: The successive layers 3a were deposited on shaped aluminum discs (30 cm diameter) that had previously been degreased and sandblasted to obtain a roughness (Ra) of 4 to 7 μm, using the base layer compositions described below (Base Layer 3a1, Base Layer 3a2 and Base Layer 3a3).

[0160] [Table 2]

[0161] [Table 3]

[0162] [Table 4]

[0163] The aqueous composition of the base layer 3a is prepared according to the working principle of a ball mill. The ball milling 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 solvent). The dispersion can also contain certain auxiliary agents (such as dispersants and antifoaming agents).

[0164] The thickness of the base layer 3a in this embodiment is between 10 and 20 μm, preferably between 12 and 15 μm.

[0165] As before, the substrate to which the continuous base layer 3a has been applied is coated with a multilayer non-stick 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. Finally, the assembly is heated to 250° C. for 1 hour. This method therefore involves only one curing step after the deposition of the various layers.

[0166] The composition of the intermediate layer 3b deposited by spraying is as follows (layer 3b1, layer 3b2 and layer 3b3).

[0167] [Table 5]

[0168] [Table 6]

[0169] [Table 7]

[0170] The composition of the finishing layer 3c deposited by spraying is as follows (layer 3c1 and layer 3c10):

[0171] [Table 8]

[0172] [Table 9]

[0173] [Table 10]

[0174] [Table 11]

[0175] [Table 12]

[0176] [Table 13]

[0177] [Table 14]

[0178] [Table 15]

[0179] [Table 16]

[0180] [Table 17]

[0181] (Method for evaluating the properties of non-stick coatings: Performance test using eggs) The characterization method for non-stick coatings using the egg test adapted from paragraph 3.3.2 of AFNOR NF D 21-511 is carried out as follows: The sample is washed and any remaining water is wiped off. The inner surface of the container body is dried in advance. The cooking vessel is heated to 140-170°C on a gas stove. Crack 60 / 65 caliber (French size) eggs and pour into the center of a hot cooking vessel. The egg is then left to coagulate (6-9 minutes). With the aid of a spatula, the egg is removed from the cooking vessel and the coating is cleaned with a damp vegetable sponge, during which the non-stick properties of the cooking vessel are evaluated. Recording is carried out as follows: Grade 100: The egg can be completely removed with a plastic spatula; Grade 75: Eggs are not completely removed, but the coating is easily cleaned with a damp sponge; Grade 50: Eggs not completely removed, but coating can be cleaned with a damp sponge; Grade 25: Eggs not completely removed and coating not cleaned with a damp sponge; Grade 0: Eggs are not removed and coating cannot be cleaned with a damp sponge.

[0182] [Table 18]

[0183] All of the silicone resin-polyester based coatings according to the invention adhere well to metal while at the same time exhibiting good non-stick properties.

Claims

1. A coated cooking element (1) for a cooking utensil or electric cooking appliance, the coated cooking element (1) having a metal substrate (2) coated on at least one surface (2a), the surface (2a) being coated with at least a base layer (3a), one or more intermediate layers (3b), and a finishing layer (3c) in this order from the metal substrate side; The base layer (3a) is made of one or more silicone resins and optionally: one or more thermoplastic polymers, and / or one or more colorants selected from the group consisting of thermochromic pigments, heat stable pigments, flakes, and mixtures thereof; and / or one or more fillers, and / or - one or more additives It consists of The one or more intermediate layers (3b) comprise one or more colorants selected from the group consisting of thermochromic pigments, heat stable pigments, flakes, and mixtures thereof, 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 It consists of The finishing layer (3c) is composed of 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 Flakes A coated cooking element (1) comprising:

2. 2. The coated cooking element (1) according to 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-phenylsilicone resins, methylsilicone-polyester resins (copolymers), phenylsilicone-polyester resins (copolymers), methyl-phenylsilicone-polyester resins (copolymers), silicone-alkyd resins (copolymers), modified silicone resins.

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

4. 4. The coated cooking element (1) of claim 1, wherein the one or more thermoplastic polymers, if present, 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), and mixtures thereof, wherein polyaryletherketone (PAEK) includes polyetherketone (PEK), polyetheretherketone (PEEK), polyetherketoneketone (PEKK), polyetheretherketoneketone (PEEKK), and polyetherketoneetherketoneketone (PEKEKK).

5. 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 5. The coated cooking element (1) according to any one of claims 1 to 4, characterized in that the coating is selected from the group consisting of: (wherein x is equal to 0 or x is between 0.001 and 0.999; y is equal to 0 or x 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, minor metals, metalloids or lanthanides; and A and M are different from each other).

6. The one or more heat stable pigments are: Titanium rutile yellow pigment; For example, stabilized bismuth vanadate (Py １８４ a yellow pigment derived from bismuth selected from red pigments, for example chosen from perylene red, iron oxides; Bismuth oxyhalide orange pigment (PO ８５ ); Bismuth vanadate orange pigment (PO ８６ ); Tin, titanium, and zinc orange pigment (PO ８２ ); Cerium sulfide orange pigment (PO ７５ ;PO ７８ ); Chromium-antimony-titanium rutile orange-yellow pigment (PBr ２４ ); Zinc tin rutile orange yellow pigment (Py ２１６ ); Tin zinc sulfide and 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 ; ・ThiO ２ ; black pigment PBk28 (copper chromite black spinel); and mixtures thereof The coated cooking element (1) according to any one of claims 1 to 5, characterized in that it is selected from the group consisting of:

7. Coated cooking element (1) according to any of claims 1 to 6, characterized in that, if present, the one or more holographic flakes are a mixture of magnetizable and non-magnetizable particles.

8. 8. Coated cooking element (1) according to any one of claims 1 to 7, characterized in that the metal substrate (2) is a substrate made of aluminum, stainless steel, cast or cast aluminum, iron, titanium or copper.

9. the thickness of the layer (3a) is between 10 and 100 μm, preferably between 20 and 85 μm, particularly preferably between 30 and 70 μm; The thickness of the layer(s) (3b) is between 1 μm and 100 μm, preferably between 2 μm and 30 μm, particularly preferably between 3 μm and 10 μm, and 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. Coated cooking element (1) according to any one of claims 1 to 8, characterized in that it is

10. 10. The coated cooking element (1) according to any one of claims 1 to 9, characterized in that the proportion of silicone resin in layer (3a) or layer (3c) is 50% by weight or more, based on the total weight of layer (3a) or layer (3c), respectively.

11. 11. Coated cooking element (1) according to any one of claims 1 to 10, characterized in that, if present, the proportion of filler in layer (3a), (3b) or (3c) is less than 10% by weight, based on the total weight of layer (3a), (3b) or (3c), respectively.

12. 12. The coated cooking element (1) according to any one of claims 1 to 11, characterized in that, if present, the proportion of additives in layer (3a), (3b) or (3c) is less than 20% by weight, based on the total weight of layers (3a) / (3b) / (3c).

13. 13. The coated cooking element (1) according to any one of claims 1 to 12, characterized in that the layers (3a) and (3c) comprise one or more thermoplastic polymers, the proportion of thermoplastic polymer in the layer (3c) being greater than the proportion of thermoplastic polymer in the layer (3a).

14. 11. A method for manufacturing a coated cooking element (1) according to any one of claims 1 to 10, said method comprising: i. Providing a metal substrate (2) having a surface (2a); ii. Optionally, pretreating the surface (2a) of the metal substrate (2) to be coated; iii. Applying a base layer (3a); iv. drying the base layer (3a); v. applying one or more intermediate layers (3b); vi. Optionally, drying the one or more intermediate layers (3b); vii. applying a finishing layer (3c); A method comprising:

15. A cooking utensil (100) comprising a coated cooking element (1) according to any one of claims 1 to 10.

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, the heating surface (6) being opposite a cooking surface (5) intended to be in contact with food during cooking.

17. 17. The cooking implement (100) according to claim 15 or 16, characterized in that it 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 broiler, a casserole, a cooker or bread machine container, a serving mold.

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

19. 19. The electric cooking appliance (200) of claim 18, characterized in that it is selected from the group consisting of an electric crepe maker, an electric raclette machine, an electric fondue machine, 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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