Non-fluorinated hybrid PEAK / Heterocyclic thermoplastic / Silicone resin coating

Abstract

The present invention relates to a coated cooking element (1) for a cooking appliance or an electric cooking appliance, a method for manufacturing the same, and a cooking appliance or cooking device including the same. At least one surface (2a) of a metal substrate (2) is coated with at least the following layers in this order from the metal substrate (2): (3a) an adhesion auxiliary layer in which 20% to 100% of the total weight of the auxiliary layer consists of a polymer (α) selected from the group consisting of PAEK and a polymer selected from the group consisting of PEI, PI, PAI, and PBI, and the weight ratio of PAEK:(PEI + PI + PAI + PBI) is 1:1 to 15:1; (3b) an intermediate layer optionally consisting of a colorant and optionally a silicone resin, a thermoplastic polymer, and / or a filler, and / or an additive; (3c) a finish layer consisting of one or more silicone resins and optionally a thermoplastic polymer, and / or a filler, and / or an additive, and / or flakes.

Description

Technical Field

[0001] The present invention is applicable to the field of anti-adhesion coatings for cooking surfaces of cooking utensils and electric cooking appliances.

Background Art

[0002] Cooking utensils coated with polytetrafluoroethylene (PTFE) can be cooked with little or no added fat and are easy to maintain, so they are popular in the market. However, an inherent weakness of these coatings is their low mechanical strength, especially at high temperatures.

[0003] To overcome this, a number of technical solutions have been proposed that consist of reinforcing the coating with a hard filler or by means of an intervening hard sublayer of inorganic or organic type.

[0004] In the case of a primer reinforced with a hard organic or inorganic filler, there is indeed a significant improvement in wear resistance, but an effect on the metal is also observed when cooking foods such as pork chops or when using a metal spatula.

[0005] For example, in the case of an inorganic hard substrate such as one made of enamel or metal oxide, the wear resistance is further improved, but the impact problem, although limited, is not eliminated.

[0006] Auxiliary layers of organic polymers are also known. These auxiliary layers can effectively reduce the appearance of scratches or even eliminate them. Therefore, this strategy is very interesting. The polymers used are very often high heat-resistant thermoplastics, for example, polyaryletherketones, especially poly(oxy-1,4-phenylene-1,4-phenylene-carbonyl-1,4-phenylene (PEEK) or polyphenylene sulfide, which have a high melting point.

[0007] PEEK has a high melting point (343 °C) and excellent thermal stability under use conditions of 260 °C, so it is interesting for cooking utensils.

[0008] To obtain an auxiliary layer from this type of polymer, coating techniques such as spray coating, roller coating, curtain coating, pad printing, screen printing, thermal spraying, electrostatic spraying, and inkjet coating can be implemented.

[0009] Patent Document 1 mentions the use of an auxiliary layer consisting only of PEEK (particle size 5 μm to 100 μm, preferably D50 20 μm) deposited on a metal substrate, and the cover is composed of 60% to 95% of the surface of the item and is then covered with a single-layer or multi-layer non-stick coating based on fluorinated resins and fluorinated copolymers. The PEEK auxiliary layer is deposited either by pad printing or screen printing, or by spraying in the form of a dispersion.

[0010] The thickness of this PEEK layer is configured between 5 μm and 100 μm.

[0011] The drawback of the described method is the need for double curing of the PEEK-based fluorinated coating. The first curing requires a temperature higher than the melting point of the polymer constituting the auxiliary layer (i.e., 380 - 400 °C in the case of PEEK) to enable the polymer constituting the auxiliary layer to adhere to the metal substrate. Next, it is necessary to substantially cool the article, which is very expensive in terms of time and energy, but it is essential that a continuous fluorinated layer that is sintered during the second curing at a high temperature (>420 °C) can be applied.

[0012] Patent Document 2 describes a hard auxiliary layer that forms a continuous network and is discontinuously deposited on the inner bottom of cooking utensils. The material constituting this layer is ceramic (alumina-titanium mixture) or metal or polymer (PAI, PEI, PI, PES, PPS, PEK or PEEK). The surface area of the cooking utensils covered with this material is composed between 30% and 80%, and the dimension between the deposited drops is composed between 2 μm and 50 μm. The surface of this hard layer has a roughness with Ra of 2 μm - 12 μm, preferably 4 μm - 8 μm.

[0013] This material is preferably sprayed by a flame spraying process in powder form having a particle size included between 20 μm and 45 μm.

[0014] Before the process of depositing the powder by flame spraying, it is necessary to preheat the metal substrate to 180 °C or higher.

[0015] Then, when the deposit is cooled to room temperature, a fluorinated layer is deposited by spray coating. Then, single sintering is performed at 430 °C.

[0016] Patent Document 3 mentions the use of a PEEK auxiliary layer. After the PAI resin and the fluorinated resin are deposited on the metal substrate, they are covered with a non-stick coating of one or more layers, and there is no PEEK in these upper layers.

[0017] The auxiliary layer is composed of a mixture of PAI, PEEK and PTFE such that PTFE is composed of 9 - 15% by weight and PAI is composed of 4 - 5% by weight.

[0018] In all cases, the dry matter content of PEEK in the final fluorinated film is about 0.12% - 1.1% by weight, preferably 0.12% - 0.9% by weight.

[0019] The PEEK powder has a particle size D50 of 5 - 35 μm.

[0020] In all cases, the first coating layer contains a fluororesin.

[0021] This liquid coating is deposited by spraying. Then, an upper layer of a fluorinated coating containing one or more bonding primers is also deposited by spraying. All of these layers are sintered by a single curing at 400 - 420 °C.

[0022] The drawback of this coating method is that the content of PEEK resin in the first layer is very low and does not achieve sufficient mechanical properties to have a scratch-resistant coating.

[0023] Patent Document 4 mentions the use of a PEEK auxiliary layer that does not contain a fluorinated resin and consists of at least 50% by weight of PEEK powder such that the surface covered with PEEK constitutes between 60% and 95% of the surface of the item.

[0024] This primer containing at least 50% PEEK may also contain a mixture with other thermally stable resins such as polyphenylene sulfide (PPS), polyetherimide (PEI), polyimide (PI), polyether ketone (PEK), polyether sulfone (PES), polyamideimide (PAI), etc.

[0025] It can also contain a filler selected from silica, mica, or metal oxides of lamellar fillers. It does not contain a fluororesin.

[0026] The first curing is carried out at a high temperature of at least 260 °C, preferably 340 °C or higher, to dissolve PEEK.

[0027] PEEK is in the form of a powder with a particle size of 4 μm - 80 μm, and D50 is preferably 20 μm. The thickness of this auxiliary layer is composed of 5 μm - 100 μm.

[0028] This liquid coating is deposited by spraying. Subsequently, an upper layer of a primer having a fluorinated coating or a fluorinated finish layer is sprayed. All of these layers are sintered by a second curing, and the fluorinated coating is sintered between 400°C and 420°C.

[0029] In Patent Document 5, it is described that the first layer contains at least 50% by weight (preferably 60% - 95%) of PEEK, mixed with heat-stable polymer resins such as PPS, PEI, PI, PAI, and mixtures thereof, and fillers such as metal oxides, silica, mica, etc., and is mixed in the absence of any fluorinated resin. This first layer has a thickness composed of 5 - 100 μm.

[0030] PEEK is a powder having a particle size of 4 μm - 80 μm and having a D50 of about 20 μm.

[0031] However, the process of obtaining such a coating necessarily involves double curing / sintering between 400 - 420°C.

[0032] Pure silicone resins are described as non-sticky and resistant to temperatures exceeding 220 - 230°C. Instead, they are regarded as having poor adhesion to the substrate.

[0033] Conversely, silicone polyester resins are very widely used in the molding industry because they adhere to the substrate and are compatible with the stamping process while being non-sticky. However, they decompose at temperatures exceeding 230°C. In fact, the operating temperature range of cooking utensils is 50 - 250°C, and in the case of induction bottoms, it is not uncommon to reach temperatures of 300°C or 350°C. Therefore, their use is not compatible with the operating temperatures in the field of cooking utensils.

Prior Art Documents

Patent Documents

[0034]

Patent Document 1

[0035] The present invention relates to a technical problem of improving the scratch resistance and peel resistance of a silicone coating by creating an auxiliary layer in contact with a metal substrate based on a thermoplastic polymer mixture having high thermomechanical properties. [Means for Solving the Problems]

[0036] A first object of the present invention relates to a coated cooking element (1) for cooking utensils or electric cooking appliances, comprising a metal substrate (2) coated in this order from the metal substrate (2) with at least the following layers on at least one surface (2a): (3a) An adhesion auxiliary layer, wherein 20% to 100% by weight of the total weight of the auxiliary layer is one or more polymers (α) selected from the group consisting of polyaryl ether ketone (PAEK), and one or more polymers selected from the group consisting of polyetherimide (PEI), polyimide (PI), polyamideimide (PAI), and polybenzimidazole (PBI), and the PAEK:(PEI + PI + PAI + PBI) weight ratio is 1:1 to 15:1, the adhesion auxiliary layer; (3b) Optionally, one or more 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 - An intermediate layer composed of one or more additives; (3c) A finishing 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 - Flakes, a finishing layer.

[0037] Another object of the present invention relates to a method for manufacturing a coated cooking element (1) according to the present invention, characterized by the following steps: i. Supplying a metal substrate (2) comprising two opposite surfaces; ii. Optionally, treating the surface (2a) of the substrate (2) to obtain a treated surface (2a) that promotes the adhesion of an adhesion assisting layer (3a) to the substrate (2); iii. Depositing one or more continuous layers of the bonding assisting layer (3a) onto the surface (2a) of the substrate (2); iv. Optionally, drying and / or sintering at a temperature exceeding 400 °C; v. Optionally, applying a layer or layers (3ab) and / or an intermediate layer or layers (3b); vi. Applying a finishing layer (3c); vii. Drying at a temperature of 230 °C to 420 °C.

[0038] Another object of the present invention relates to a cooking utensil (100) comprising a coated cooking element (1) according to the present invention.

[0039] Another object of the present invention relates to an electric cooking appliance (200) comprising a coated cooking element (1) according to the present invention and a heat source (210) configured to heat the coated cooking element (1).

Brief Description of the Drawings

[0040]

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DETAILED DESCRIPTION OF THE INVENTION

[0041] Definition For the purposes of the present invention, the term "layer" should be understood to mean a continuous or discontinuous layer. A continuous layer (also called a monolithic layer) is a single entity that forms a solid block that completely covers the surface on which it is placed. A discontinuous layer (or non - monolithic layer) can contain a plurality of parts and is not a single entity.

[0042] The terms "base layer", "primary layer", "adhesive layer" or "adhesive primer" are understood to mean all layers of the first layer applied directly to the substrate (this layer preferably adheres well to the substrate and imparts all its mechanical properties, i.e., hardness, scratch resistance, to the coating).

[0043] The term "finish layer" or "finish" is understood to mean a continuous and transparent surface layer that protects the decorative layer from mechanical damage and imparts anti - adhesion properties to the coating while fully visualizing the decorative layer. Preferably, the last finish layer is intended to come into contact with food.

[0044] The term "decoration" or "decoration layer" is understood to mean one or more continuous or discontinuous layers containing a pigment composition. The decoration can be in the form of one or more patterns and one or more colors. The decoration is clearly visible to the user with the naked eye and at a conventional distance for household use.

[0045] The term "overlapping layer" is understood to mean layers that are partially or fully superimposed. These layers may be in the form of partially overlapping patterns, for example, in the form of concentric disks.

[0046] The term "adjacent layer" is understood to mean layers that are not superimposed. These layers can be in the form of the same or different non - superimposed patterns and are preferably uniformly distributed.

[0047] The term "reference temperature pigment composition" is understood to mean a composition containing a pigment that indicates to the user that the optimal use temperature has been reached at a given temperature. This indication is made by comparing the color of the thermochromic pigment composition and the color of the reference temperature pigment composition. It is either the case that the optimal use temperature is reached when the colors are the same, or the optimal use temperature is reached when the colors are visually very different.

[0048] The "reference temperature pigment composition" can contain a pigment having the following: - At the optimal temperature of use, it has the same color as the thermochromic pigment composition, * This pigment has the same color as the thermochromic pigment composition at the optimal use temperature at room temperature, and the color does not change with temperature. Therefore, * Or, this pigment has a color different from the color of the thermochromic pigment composition at room temperature and changes to the same color as the thermochromic pigment composition at the optimal use temperature. Therefore, - Regardless of whether this pigment changes color with temperature change, a color very different from the color of the thermochromic pigment composition at the optimal use temperature.

[0049] The optimal use temperature can be achieved when the color of the reference temperature pigment composition corresponds to the color shown in the user guide of the household item including the coating of the present invention, or the color shown on the color scale provided to the user together with the item.

[0050] The pigment composition at the reference temperature is thermochromic or thermally stable.

[0051] The reference temperature pigment composition can be, for example, a cooking reference temperature pigment composition or an indication of the risk of overheating.

[0052] The present invention has at least one of the following advantages: - The coating according to the present invention has a thermochromic functionality with clear visibility and has a contrasting color change over a targeted central temperature range, such as near the cooking temperature of food for cooking utensils. - The coating according to the present invention can provide good temperature control during food cooking, which is necessary not only for health and taste reasons but also to limit overheating that weakens the coating and for safety. - The thermochromic properties of the thermochromic pigment composition are reversible, meaning that after the color changes under the influence of heat, when the temperature decreases, the compound returns to its initial state and initial color, and this color change cycle (reversibility) can be repeated infinitely. - The coating according to the present invention has high thermal stability during temperature rise and is stable up to about 450°C.

[0053] For the purposes of the present invention, the expression "thermochromic semiconductor" should be understood to mean an inorganic or organic compound that exhibits a reversible color change in response to an increase in temperature. The gradual and reversible thermochromism of these semiconductor compounds is related to a decrease in the bandgap width of the semiconductor due to the expansion of the material. In fact, the periodicity of the anion and cation network leads to the gathering of energy levels into energy bands. The energy band filled with higher energy is called the valence band, and the empty energy band with lower energy is called the conduction band. There is a forbidden band called a gap between these two bands. The color of a semiconductor material can result from the presence of charge transfer corresponding to the passage of electrons from the valence band to the conduction band on the same atom, or generally, from the presence of charge transfer corresponding to the passage of electrons from the orbit of an anion to the orbit of a cation (interatomic photon absorption).

[0054] In the application fields envisioned for the present invention, the coating reaches optimal conditions when it reaches a temperature suitable for cooking food, preferably 100 to 250 °C.

[0055] For the purposes of the present invention, "thermochromic pigment or pigment composition" should be understood to mean a pigment or pigment composition that changes color as a function of temperature within a given temperature range, and this change is reversible. This color change is visible to the user with the naked eye and can be used at conventional distances.

[0056] The term "thermally stable pigment" is understood to mean a pigment that does not exhibit a color change when exposed to a temperature increase within a given temperature range, or exhibits a color change so low that it is not visible to the user with the naked eye and at conventional distances when exposed to a temperature increase within a given temperature range.

[0057] Preferably, the thermally stable pigment has a color difference ΔE * of less than 10 between 25 °C and 200 °C, and ΔE * is defined by the CIE1976 formula in the CIELAB color space.

[0058] [Number]

[0059] (L1 * , a1 * and b1 * characterize the L * a * b value of the compound at room temperature, and L2 * , a2 * and b2 * characterize the L * a * b value of the compound at 200 °C.)

[0060] The expression "the colors are the same" shall mean that the user cannot distinguish them with the naked eye and cannot distinguish them at the conventional use distance.

[0061] For the purposes of the present invention, the expression "cooking utensils" should be understood to mean an object intended for cooking. For this purpose, it is intended to be heat-treated.

[0062] The expression "an object intended to be heat-treated" should be understood, for the purposes of the present invention, to mean an object that is heated by an external heating system such as a frying pan, a pot, a sauté pan, a Chinese wok, a barbecue grill, etc., and can transfer the heat energy supplied by this external heating system to the material or food in contact with the object.

[0063] The expression "electric cooking appliances" should be understood, for the purposes of the present invention, to mean a heating object having its own heating system such as an electric crepe maker, an electric raclette maker, an electric fondue maker, an electric grill, a hot plate, an electric cooking appliance, a bread maker, and an electric pressure cooker.

[0064] "Silicone resin-based coating" is understood to mean a coating containing one or more silicone resins in one or more of its layers.

[0065] "Coating" is understood to mean all layers that cover and adhere to the metal substrate. The coating according to the present invention obtained is preferably solid. "Solid" is understood to mean the property of an adhesive material that is insoluble in water, in normal solvents, or in food components such as aqueous or fatty mixtures, and the material may be very hard or very flexible such as an elastomer.

[0066] In the present invention, % by weight is expressed as dry weight, i.e., without solvent.

[0067] A first object of the present invention relates to a coated cooking element (1) for cooking utensils or electric cooking appliances, comprising a metal substrate (2) coated with at least the following layers in this order from the metal substrate (2) on at least one surface (2a): (3a) An adhesion-promoting layer, wherein 20% to 100% by weight of the total weight of the auxiliary layer is one or more polymers (α) selected from the group consisting of polyaryl ether ketone (PAEK), and one or more polymers selected from the group consisting of polyetherimide (PEI), polyimide (PI), polyamideimide (PAI), and polybenzimidazole (PBI), and the PAEK:(PEI + PI + PAI + PBI) weight ratio is 1:1 to 15:1, the adhesion-promoting layer; (3b) Optionally, one or more 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, the intermediate layer; (3c) A finishing 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 - a finishing layer consisting of flakes.

[0068] Advantageously, layer (3a), optionally layer (3b) and layer (3c) form a coating (3) that coats the metal substrate (2). This coating (3) has anti-adhesion properties and forms an anti-adhesion coating.

[0069] Advantageously, layer (3a) contacts the metal substrate (2) through one of its surfaces via its surface (2a).

[0070] Thus, at least one coated surface (2a) of the metal substrate is a cooking surface. In other words, the coating of the cooking element (1) according to the invention is intended to come into contact with food.

[0071] The coating of the cooking element (1) according to the invention does not contain fluoropolymers. In other words, the said coating is a fluoropolymer or lacks fluoropolymers.

[0072] The coating of the cooking element (1) according to the invention is intended to come into contact with food.

[0073] Advantageously, the finishing layer (3c) contacts food through one of its surfaces and thus forms a cooking surface (5).

[0074] Advantageously, the thickness of layer (3b) is configured to be between 1 μm and 100 μm, preferably between 2 μm and 30 μm, particularly preferably between 3 μm and 10 μm.

[0075] Advantageously, the thickness of layer (3c) is configured to be between 0.05 μm and 100 μm, preferably between 0.08 μm and 20 μm, particularly preferably between 0.1 μm and 10 μm.

[0076] According to one embodiment, the thickness of layer (3c) is configured to be between 0.1 μm and 2 μm, preferably between 0.2 μm and 1.5 μm. In a particular embodiment of the invention, the thickness of layer (3c) is 100 nm + / - 5 nm.

[0077] According to another embodiment, the thickness of the layer (3c) is 10 μm to 100 μm, preferably 20 μm to 85 μm, particularly preferably 30 μm to 70 μm.

[0078] The coating of the cooking element (1) according to the invention may optionally include one or more layers (3a) sandwiched between the layer(s) (3a) and the layer(s) (3b), or between the layer(s) (3a) and the layer(s) (3c) 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.

[0079] Advantageously, the thickness of the layer (3ab) is configured to be between 0.05 μm and 100 μm, preferably between 0.08 μm and 20 μm, particularly preferably between 0.1 μm and 10 μm.

[0080] Adhesive auxiliary layer (3a) Advantageously, the adhesion assisting layer (3a) contains one or more polymers (β) selected from the group consisting of polyphenylene sulfide (PPS) and polyether sulfone (PES), and preferably, it is in an amount of at least 20% by weight, preferably at least 25% by weight, of the total weight of the auxiliary layer of one or more polymers selected from the group consisting of polyphenylene sulfide (PPS) and polyether sulfone (PES).

[0081] Advantageously, the adhesion assisting layer (3a) contains less than 40% by weight, preferably less than 30% by weight, preferably 5 - 25% by weight of the total weight of the filler assisting layer.

[0082] Advantageously, the adhesion assisting layer (3a) contains one or more acrylic resins. The acrylic resin is preferably selected from the group consisting of polymers derived from emulsion polymerization of various monomers and other acrylic monomers.

[0083] Advantageously, the adhesion assisting layer (3a) contains one or more colorants.

[0084] Advantageously, the colorant(s) in the adhesion assisting layer (3a) represent less than 30% by weight, preferably less than 20% by weight, of the total weight of the assisting layer.

[0085] Advantageously, the polyaryl ether ketone (PAEK) is selected from the group consisting of polyether ketone (PEK), polyether ether ketone (PEEK), polyether ketone ketone (PEKK), polyether ether ketone ketone (PEEKK), and polyether ketone ether ketone ketone (PEKEKK).

[0086] Advantageously, the polymer(s) (α) is selected from the group consisting of polyether ether ketone (PEEK) and polyamideimide (PAI).

[0087] Advantageously, when the polymer (α) occupies 20 - 40% of the assisting layer according to the present invention, the weight ratio of PAEK:(PEI + PI + PAI + PBI) is composed of 6:1 - 12:1.

[0088] Advantageously, when the polymer (α) represents 40 - 80% of the assisting layer according to the present invention, the weight ratio of PAEK:(PEI + PI + PAI + PBI) is composed of 12:1 - 15:1.

[0089] Advantageously, the polymer (α) represents 25 - 40% by weight, preferably 25 - 35% by weight, of the total weight of the assisting layer.

[0090] The weight ratio between the polymer (α) and the polymer (β) is advantageously composed of 2:5 - 2:3, preferably 1:2 - 1:3.

[0091] Advantageously, the polyaryl ether ketone (PAEK) is selected from the group consisting of polyether ketone (PEK), polyether ether ketone (PEEK), polyether ketone ketone (PEKK), polyether ether ketone ketone (PEEKK), and polyether ketone ether ketone ketone (PEKEKK), and particularly preferably is PEEK.

[0092] Advantageously, the polymer(s) (α) is selected from the group consisting of polyaryl ether ketone (PAEK) and polyamide imide (PAI) and mixtures thereof. In a particularly preferred embodiment, the moiety (α) is a mixture of PAEK and PAI polymers.

[0093] Advantageously, the polymer(s) (α) is selected from the group consisting of polyether ether ketone (PEEK) and polyamide imide (PAI), and mixtures thereof. In a particularly preferred embodiment, the moiety (α) is a mixture of PEEK and PAI polymers.

[0094] Advantageously, the polymer (β) is polyether sulfone (PES).

[0095] In a preferred embodiment of the present invention, the moieties (α) and (β) are a mixture consisting of PEEK, PAI and PES polymers.

[0096] Advantageously, the adhesion assisting layer (3a) can also contain one or more solvents, preferably polar aprotic solvents, preferably non-labeled solvents such as N-formylmorpholine (NFM), N-methylimidazole (NMI), N-butylpyrrolidone (NBP) and dimethyl sulfoxide (DMSO), or alcoholic solvents such as propylene glycol (PPG) and diethylene glycol.

[0097] Advantageously, the adhesion assisting layer (3a) may contain one or more surfactants.

[0098] Advantageously, the adhesion assisting layer (3a) may also contain one or more defoamers.

[0099] In a preferred embodiment of the present invention, the adhesion assisting layer (3a) is a mixture consisting of PEEK, PAI, PES, and optionally a filler, an acrylic resin, and a colorant.

[0100] Subsequently, the thickness of the auxiliary layer (3a) is preferably configured to be between 10 and 100 μm, preferably between 20 and 80 μm, and preferably between 30 and 60 μm.

[0101] Metal substrate Advantageously, the metal substrate (2) (also called the carrier) is a substrate made of aluminum, stainless steel, cast iron or cast aluminum, iron, titanium or copper.

[0102] For the purposes of the present invention, aluminum is understood to mean a metal composed of 100% aluminum or an aluminum alloy.

[0103] Advantageously, the metal substrate (2) is an aluminum substrate, a stainless steel substrate, or a multi-layer metal substrate. The metal substrate (2) may be a two-layer or three-layer substrate, and these multi-layers (plural possible) can be obtained, for example, by co-lamination, by solid bonding, or by impact bonding at high or low temperature.

[0104] Preferably, the metal substrate (2) includes alternating layers of metal and / or metal alloy.

[0105] According to one embodiment, the metal substrate (2) is an aluminum alloy substrate, a stainless steel substrate, or a multi-layer metal substrate having an aluminum alloy or stainless steel surface (2a).

[0106] Preferably, the metal substrate (2) is an aluminum substrate.

[0107] Advantageously, the thickness of the metal substrate (2) is configured to be between 0.5 mm and 10 mm.

[0108] Advantageously, the surface (2a) of the metal substrate (2) has been previously subjected to a surface treatment that enables improving the adhesion of the coating to the substrate.

[0109] According to one embodiment, the surface of the surface (2a) of the metal substrate (2) has undergone a surface treatment, and the surface treatment is chemical etching, brushing, hydration, sandblasting, shot blasting, physical and chemical treatment of the plasma or corona or laser type, chemical activation, or a combination of these different techniques.

[0110] Advantageously, the surface (2a) of the substrate to which the coating (3) according to the invention is applied can be treated so as to increase its specific surface area. In the case of an aluminum substrate, this treatment can be carried out by anodization (creation of a tubular alumina structure), by chemical etching, by sandblasting, by brushing, by shot blasting, or by adding material by techniques such as thermal spraying (flame, plasma or arc spraying). Other metal substrates can also be polished, sandblasted, brushed, microbead blasted, or can receive additional material by techniques such as thermal spraying (flame, plasma or arc spraying).

[0111] The metal substrates that can be used in the present invention are advantageously anodized or non-anodized aluminum substrates (optionally polished, brushed, sandblasted, shot blasted or microbead blasted), anodized or non-anodized aluminum alloy substrates (optionally polished, brushed, sandblasted or microbead blasted), stainless steel substrates (optionally polished, brushed, sandblasted or microbead blasted, steel substrates, optionally polished, brushed, sandblasted or microbead blasted), cast steel, aluminum or iron substrates, copper substrates (optionally hammered or polished).

[0112] Advantageously, the substrate can be selected from a substrate comprising a ferrite-based stainless steel / aluminum / austenitic stainless steel layer, a substrate comprising a stainless steel / aluminum / copper / aluminum / austenitic stainless steel layer, a cast aluminum backfilled with an outer stainless steel bottom, a shell made of aluminum or an aluminum alloy, a metal co-deposited substrate, for example, a two-layer co-deposited substrate comprising a stainless steel layer (e.g., intended to form the inner surface of the item) and an anodized or non-anodized layer of aluminum or an aluminum alloy intended to form the outer surface of the item.

[0113] Advantageously, the arithmetic mean roughness Ra of the surface of the face (2a) of the metallic substrate (2) is 1 μm or more.

[0114] The arithmetic mean roughness Ra is measured using a roughness meter in accordance with ISO 4287. Ra is the arithmetic mean of the deviations from the mean. The surface topography can be studied in particular using a profilometer equipped with a probe with a fine stylus having a diamond tip, or an optical measuring device such as Altisurf® which enables non-contact measurement using a confocal chromaticity sensor. This study of the surface topography makes it possible to define the mean arithmetic roughness Ra.

[0115] Silicone resin In the text of the description, the expression "silicone resin" is used synonymously to denote silicone before or after crosslinking. In the text of the description, the expression "silicone" denotes an organopolysiloxane material. Crosslinking is the step of converting 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 which is crosslinked to obtain a three-dimensional network forming the material called silicone resin in the description.

[0116] This crosslinking can be carried out by thermal activation or by chemical activation using a catalyst such as platinum, for example.

[0117] The silicone resin may preferably be obtained from a precursor soluble in a solvent or in an emulsion in water, for example a crosslinkable oil or resin, which is particularly selected from hydrogenated silicon, silicone oil resins containing at least one vinyl group (-CH=CH2), silicone resins or silicone-polyester resins (copolymers) containing at least one alkoxy group, such as methoxy or ethoxy, and / or silicones or silicone-polyester resins (copolymers) containing at least one alkoxy group (particularly selected from ethoxy, or hydroxy groups, and mixtures thereof). These precursors can be crosslinked to obtain a silicone resin characterized by its insolubility and substantially solid form.

[0118] Preferably, these precursors are polymers or oligomers in the form of silicone oils of variable degrees of branching, or in the form of pre-crosslinked silicone resins or copolymers of silicone resins such as silicone-polyester, silicone-alkyd, silicone-polyurethane or silicone-epoxy resins, or in the form of mixtures of silicone oils, silicone resins and copolymers of silicone resins. The silicon atoms can be substituted by alkyl (particularly methyl) or aryl (particularly phenyl) groups or mixtures thereof. The oil or resin preferably contains one or more (two or more) hydroxy or alkoxy functional groups (particularly methoxy, ethoxy, butoxy) as substituents of the silicon atoms.

[0119] Preferably, the silicone resin obtained after crosslinking of these precursors, i.e., after being crosslinked, is selected from the group consisting of methyl silicone resins and / or phenyl silicone resins and / or methylphenyl silicone resins, methyl silicone-polyester resins (copolymers), phenyl silicone-polyester resins (copolymers), methylphenyl silicone-polyester resins (copolymers), silicone-alkyd resins (copolymers), modified silicone resins and mixtures thereof.

[0120] Advantageously, the silicone resin is selected from the group consisting of methyl silicone resin and / or phenyl silicone resin and / or methylphenyl silicone resin, methyl silicone polyester resin (copolymer), phenyl silicone polyester resin (copolymer), methylphenyl silicone polyester resin (copolymer), silicone alkyd resin (copolymer), modified silicone resin, and mixtures thereof.

[0121] The silicone resin can be obtained from precursors selected in particular from hydrogenated silicon, silicone resins containing at least one vinyl group (-CH=CH2), silicone-polyester resins (copolymers) containing at least one methoxy group, and / or silicone-polyester resins (copolymers) containing at least one ethoxy group, and mixtures thereof.

[0122] The single layer (3) of silicone resin can form a network composed of a combination of four simple organosiloxane units denoted M, D, T, and Q, depending on the degree of substitution of silicon atoms by oxygen, as described in the following table, where R is an organic substituent described below.

[0123]

Table 1

[0124] The organopolysiloxane material or polymer can be obtained by crosslinking from a monomer or a precursor that can be a polymer, or by crosslinking from an intermediate that can be an oligomer. The organopolysiloxane polymer can also be obtained from a mixture of these different types of precursors. When the network contains more T and Q units than D, the crosslink density is higher. The distribution between M, D, T, and Q units depends on the chemical structure of the precursor, in particular this distribution M, D, T, Q within the precursor.

[0125] The polymer precursor is an organopolysiloxane. These macromolecules are formed from M, D, T, and / or Q units as described in the table, where R is independently an alkyl group, especially methyl, or aryl, especially phenyl, and different types of R can be present on the same macromolecule.

[0126] The organopolysiloxane can be either linear or slightly branched (most of the D groups), or branched or highly branched (most of the T and Q groups). Linear or slightly branched organopolysiloxanes are generally liquids, 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 resin is in a substantially solid form or, provided it has a fairly low molecular weight, in a liquid form, especially in the form of a solution in a solvent or an aqueous emulsion. They can be copolymerized with organopolymers or oligomers that do not contain silicon, especially those selected from polyester, acrylic, alkyd, polyurethane, and epoxy resins.

[0127] When the crosslinking is hydrolysis-condensation, it is carried out by reactive hydroxy or alkoxy functional groups present on the organopolysiloxane, especially methoxy, ethoxy, or butoxy.

[0128] When the crosslinking is addition polymerization (or hydrosilylation), it is carried out by the reaction between a vinyl-reactive functional group (-CH=CH2) present in one of the organopolysiloxanes and a hydrosilicon (Si-H) reactive functional group present in another organopolysiloxane mixed with the first one.

[0129] All of these reactive functional groups are present in at least one number on each organopolysiloxane and can be present in numbers of 2, 3, or more as long as the molecular structure permits. A silicone oil containing at least one reactive function is called a "reactive oil". The reactive functional groups can be at the ends (terminals) of the macromolecular chains or distributed along the chains.

[0130] The silicone polyester resin, in particular, has a silicone / polyester mass ratio, for example, 90 / 10, 80 / 20, 70 / 30, 60 / 40, 50 / 50, 40 / 50, 30 / 70, 20 / 80, 10 / 90, and is preferably between 80 / 20 and 50 / 50.

[0131] Pure or pre-emulsified linear PDMS silicone oils in water are characterized by a molecular weight that is a direct increasing function of the viscosity of the pure oil. They are then characterized by the presence or absence of reactive functional groups, for example, hydroxyl functional groups (silanols) on silicon atoms, their number, and their position on the molecular chain. For example, reactive oils having a viscosity composed between 50 and 20,000 MPa·s, particularly between 300 and 5,000 MPa·s, may be used, having at least one reactive functional group, preferably at least two reactive functional groups, which may be arranged at the ends of the chain.

[0132] Examples of polymer precursors that react by addition polymerization include polymethylhydrosiloxane, vinylmethylsiloxane, (particularly linear) vinyl-terminated polydimethylsiloxane (PDMS), vinyl-terminated diphenylsiloxane-dimethylsiloxane copolymer, hydride-terminated polydimethylsiloxane, hydride-terminated polyphenylmethylsiloxane, cyclic vinylmethylsiloxane, vinyl-MQ resin, trimethylsilyl-terminated polymethylhydrosiloxane, methylhydrosiloxane and trimethylsiloxane-terminated dimethylsiloxane copolymer, hydrogenated MQ resin, etc., as well as combinations thereof.

[0133] The polymeric precursors that react by hydrolysis-condensation can be silicone resins or silicone oils, for example, poly(methylsilsesquioxane), poly(propylsilsesquioxane), poly(phenylsilsesquioxane), polydimethylsiloxane (PDMS), trimethylsilyl-terminated polydimethylsiloxane (PDMS), hydroxyl-terminated polydimethylsiloxane (PDMS), silanol-terminated polydimethylsiloxane (PDMS), silanol-terminated polyphenylsiloxane (PDMS), silanol-terminated diphenylsiloxane-dimethylsiloxane copolymer, poly(2-acetoxyethylsilsesquioxane), organically modified alkoxysilanes and their oligomers, and all similar macromolecules thereof, and mixtures thereof can be included.

[0134] Organic polysiloxane materials or polymers can also be obtained by crosslinking one or more monomer precursors and mixtures of one or more polymeric precursors as described above, and one or more oligomeric precursors that can be linear, branched or cyclic. These oligomeric precursors have a lower molecular weight than the polymeric precursors. In order to promote the high crosslink density of the finally obtained organic polysiloxane polymer, polymers and / or oligomeric precursors containing several reactive functional groups greater than 2, preferably far greater than 2, can be added to the mixture as a co-binder.

[0135] Whether copolymerized with an organic polymer or not, monomers, oligomers and / or polymeric precursors, especially silicone resins, serve as polymer binders to obtain a solid organopolysiloxane polymer combined with the thermoplastic resin of each layer.

[0136] When silicone oil-type organic polysiloxane precursors are added in small amounts (usually 0.1 - 5% dry) to the overall formulation of the layer, independent of other components for the formation of the solid organopolysiloxane polymer, they can be regarded as additives.

[0137] Catalysts may be required for crosslinking. - In the case of crosslinking of organopolysiloxanes by hydrolysis - polycondensation, the formulation may include metal catalysts such as platinum, tin, zinc, zirconium, and cerium - based metal complexes, especially platinum - cyclovinylmethyl - siloxane complexes, tin ethylhexanoate, zinc ethylhexanoate, zirconium ethylhexanoate, cerium ethylhexanoate, and tin dibutyl laurate. - When crosslinking organopolysiloxanes by hydrosilylation, the addition of a catalyst may be necessary: this can be, for example, a suitable platinum - based catalyst such as a platinum or Karstedt catalyst or an Ashby catalyst.

[0138] A crosslinking agent, for example, a crosslinking agent having an Si - H bond, may be present.

[0139] According to one embodiment, the proportion of the silicone resin in the layer (3b) is 20% by weight or more, respectively, based on the total weight of the layer (3b).

[0140] According to other embodiments, the proportion of the silicone resin in the layer (3b) is 40% by weight or more, respectively, based on the total weight of the layer (3b).

[0141] According to still other embodiments, the proportion of the silicone resin in the layer (3b) is 50% by weight or more, respectively, based on the total weight of the layer (3b).

[0142] According to one embodiment, the proportion of the silicone resin in the layer (3c) is 20% by weight or more, respectively, based on the total weight of the layer (3c).

[0143] According to other embodiments, the proportion of the silicone resin in the layer (3c) is 40% by weight or more, respectively, based on the total weight of the layer (3c).

[0144] According to still other embodiments, the proportion of the silicone resin in the layer (3c) is 50% by weight or more, respectively, based on the total weight of the layer (3c).

[0145] According to one embodiment, the proportion of the silicone resin in the layer (3ab) is 20% by weight or more with respect to the total weight of the layer (3c), respectively.

[0146] According to another embodiment, the proportion of the silicone resin in the layer (3ab) is 40% by weight or more with respect to the total weight of the layer (3ab), respectively.

[0147] According to still another embodiment, the proportion of the silicone resin in the layer (3ab) is 50% by weight or more with respect to the total weight of the layer (3ab), respectively.

[0148] Thermoplastic polymer Advantageously, the thermoplastic polymer is selected from the group consisting of polyether sulfone (PES), polyphenylene ether sulfone (PPSU), polyamideimide (PAI), polyimide (PI), poly(phenylene oxide) (PPO), poly(arylene sulfide) (PAS), polyetherimide (PEI), and polybenzimidazole (PBI), liquid crystal polymer (LCP), polyphenylene sulfide (PPS), polyaryl ether ketone (PAEK) including polyether ketone (PEK), polyether ether ketone (PEEK), polyether ketone ketone (PEKK), polyether ether ketone ketone (PEEKK), polyether ketone ether ketone ketone (PEKEKK), and mixtures thereof.

[0149] Heterocyclic thermoplastic polymer Preferable examples of the heterocyclic thermoplastic polymer according to the present invention include polyetherimide (PEI), polyimide (PI), polyamideimide (PAI), and polybenzimidazole (PBI), or mixtures thereof.

[0150] PAEK Advantageously, the polyaryl ether ketone (PAEK) is selected from the group consisting of polyether ketone (PEK), polyether ether ketone (PEEK), polyether ketone ketone (PEKK), polyether ether ketone ketone (PEEKK) and polyether ketone ether ketone ketone (PEKEKK), and in a particularly preferred manner, it is PEEK.

[0151] Advantageously, the properties of the thermoplastic polymer(s) in layers (3b) and (3c) may be the same or different.

[0152] Advantageously, layer (3b) contains one or more thermoplastic polymers, preferably less than 30%, preferably less than 20% by weight ratio of said layer.

[0153] Advantageously, layer (3c) contains one or more thermoplastic polymers, preferably less than 50%, preferably less than 40% by weight ratio of said layer.

[0154] Advantageously, layer (3ab) contains one or more thermoplastic polymers, preferably less than 50%, preferably less than 40% by weight ratio of said layer.

[0155] According to one embodiment, layers (3b) and (3c) contain one or more thermoplastic polymers, and the proportion of the thermoplastic polymer in layer (3c) is preferentially greater than the proportion of the thermoplastic polymer in layer (3b).

[0156] According to another embodiment, layers (3b) and (3c) contain one or more thermoplastic polymers, and the proportion of the thermoplastic polymer in layer (3b) is greater than the proportion of the thermoplastic polymer in layer (3c).

[0157] Filler The filler for the purposes of the present invention makes it possible to provide mechanical reinforcement and can provide hydrophobic properties while improving the mechanical strength and thermal conductivity of the coating.

[0158] The filler does not have a single function of providing color to the coating, but can contribute to it.

[0159] The presence of a filler with excellent thermal conductivity makes it possible to compensate for the low thermal conductivity of the PAEK polymer.

[0160] Advantageously, the filler is selected from the group consisting of ceramic fillers (such as SiO2) and / or minerals and / or metal fillers (such as Al2O3, TiO2) and / or silica and / or diamond particles.

[0161] Preferably, the filler is selected from the group consisting of metal oxides, metal carbides, metal oxynitrides, metal nitrides, and mixtures thereof.

[0162] Advantageously, the metal is a transition metal, such as at least one of the elements selected from B, Ni, Ti, Zr, or Hf.

[0163] More preferably, the filler is selected from the following groups: - Reinforcing fillers: organic or inorganic hard fillers. The inorganic hard fillers are preferably silicon carbide or alumina or zirconia or graphite, or ceramics, or carbonates, or aluminum hydroxide hydrate, aluminum hydroxide or particles of one or more metal oxides, graphite, graphene; - Other reinforcing fillers selected from metal oxides: clays such as silica, mica, lamellar fillers, montmorillonite, sepiolite, diopside, kaolinite and laponite, zinc oxide, quartz, and zirconium phosphate, alumina, zirconia, zinc oxide, copper oxide, iron oxide; - Fillers selected from reinforcing fibers: glass or carbon or aramid fibers; - Conductive fillers containing transition metal carbides and / or transition metal nitrides, characterized in that the transition metal is at least one of the elements selected from B, Ni, Ti, Z, or Hf. For example, boron nitride, diamond particles, metal particles, - Lamellar fillers such as clay, graphene or graphite that can impart lubricating properties.

[0164] Preferred fillers in combination with organopolysiloxanes are as follows: - Reinforcing fillers: silica or carbonates, with a filler content of at least 10 - 15 wt% and at most 60 wt%; - Alumina, alumina hydrate, aluminum hydroxide, - Silica (precipitated or pyrogenic) with D50 < 0.1 μm and BET specific surface area > 30 m 2 / g, preferably 30 - 500 m 2 / g, - Or a mixture of quartz and silica, diatomaceous earth or ground quartz, titanium, mica, talc, kaolin, barium sulfate, slaked lime, zinc oxide, expanded vermiculite, unexpanded vermiculite, calcium carbonate, etc.

[0165] More preferably, the filler is selected from the group consisting of alumina, silicon carbide, tungsten carbide, boron nitride, quartz, and mixtures thereof.

[0166] Advantageously, the filler present in the auxiliary layer (3a) is an inorganic hard filler, preferably a metal oxide, metal carbide, metal nitride, preferably alumina, silicon carbide or pyrogenic silica.

[0167] Certain inorganic hard fillers such as silicon carbide also have the advantage of being a conductive filler in addition to their mechanical reinforcement performance, and thus provide excellent thermal conductivity.

[0168] By adding this type of filler, it becomes possible to improve the cooking result by better diffusion of heat from the metal substrate to the food in contact with the coating.

[0169] Advantageously, the average diameter D50 of the filler is composed of 0.1 - 50 μm, more advantageously 5 - 15 μm.

[0170] Advantageously, the proportion of the filler in the layer is composed of 0.5 to 30%, preferably 5 to 20% by dry weight based on the total weight of the layer after curing.

[0171] Advantageously, the proportion of the filler in layer (3a) is more than 20% by weight, preferably more than 30% by weight based on the total weight of the layer.

[0172] Advantageously, the proportion of the filler in layer (3c) is less than 10% by weight based on the total weight of the layer.

[0173] Advantageously, the proportion of the filler in layer(s) (3ab) is less than 10% by weight based on the total weight of the layer.

[0174] Advantageously, the proportions of the filler in layers (3a), (3ab), (3b) and (3c) may be the same or different.

[0175] Advantageously, the properties of the filler in layers (3a), (3ab), (3b) and (3c) may be the same or different.

[0176] Additive Advantageously, the additive is selected from the group consisting of an antifoaming agent, a dispersant, a wetting agent, a thickening agent, a pH adjuster, and a reactive silicone oil.

[0177] The antifoaming agent is preferably selected preferentially from the group consisting of mineral oil, diol, hydrocarbon, glyceride, oxirane and emulsified fatty acid.

[0178] The surfactant is preferably selected from the group consisting of glycol ether, ethoxylated alcohol excluding alkylphenol ethoxylate (APE), and gemini-type surfactant.

[0179] The dispersant is preferably selected from the group consisting of anionic dispersants such as fatty acid derivatives.

[0180] The tackifier is preferably selected from the group consisting of acrylic or polyurethane copolymers, cellulose, and pyrogenic silica.

[0181] The pH adjuster is preferably selected from the group consisting of ammonia, amines (such as triethylamine and triethanolamine), hydroxides (such as sodium hydroxide and potassium hydroxide), and carbonates.

[0182] Advantageously, the proportion of the additive in layer (3a) is less than 1% by weight based on the total weight of the layer.

[0183] Advantageously, the proportion of the additive in layer (3c) is less than 20% by weight based on the total weight of the layer.

[0184] Advantageously, the proportion of the additive in layer (3ab) is less than 20% by weight based on the total weight of the layer.

[0185] Colorant Advantageously, the colorant is selected from the group consisting of thermochromic pigments, heat-stable pigments, flakes, preferably holographic flakes, and mixtures thereof.

[0186] Advantageously, the proportion of the colorant in layers (3b) and (3c) is 0.5 to 50% by dry weight based on the total weight of the layer after curing.

[0187] Advantageously, the proportion of the colorant in layer (3b) is in the range of 10 to 40% by weight based on the total weight of the layer.

[0188] Advantageously, the proportion of the colorant in layer (3c), if present, is less than 10% by weight based on the total weight of the layer.

[0189] Advantageously, the proportions of the colorant in layers (3b) and (3c) may be the same or different.

[0190] Advantageously, the nature of the colorant in layers (3b) and (3c) may be the same or different.

[0191] Thermochromic pigment Preferably, the thermochromic pigment(s) is selected from the group consisting of 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; -x is equal to 0, or x is composed between 0.001 and 0.999; -y is equal to 0, or is composed 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.

[0192] When A and M are different from each other: -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 can be selected from Sc, TiCr, Mn, Fe, Co, Ni, Cu, Y, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Ta, W, and 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, and Ir; -A is a poor metal and can be selected from Al, An, Ga, In, Sn; -M is a poor metal and can be selected from Al, Zn, Ga, In and 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, 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, and Lu; -M is a lanthanide and can be selected from La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu.

[0193] Preferably, different A and M from each other are B and / or Mg.

[0194] [[ID=I7]] Preferably, the pigment (Bi 1-x A x )(V 1-y M y )O4 has a monoclinic scheelite crystallographic form at room temperature.

[0195] Preferably, x and y are equal to 0, that is, the pigment (Bi 1-x A x )(V 1-y M y )O4 is bismuth vanadate (BiVO4). Advantageously, BiVO4 with a monoclinic scheelite crystal structure is used at room temperature.

[0196] Bismuth vanadate is a yellow inorganic compound of the formula BiVO4 that is widely used because of its coloring properties and the absence of its toxicity. It is recorded in the Color Index International database as Q.I. Pigment Yellow 184 and is sold, among others, by Heubach (Vanadur®), BASF (Sicopal®), FERRO (Lysopac) or Bruchsaler Farbenfabrik (Brufasol®).

[0197] Thermal stability pigment Preferably, the heat-stable pigments are selected from the group consisting of: - Rutile titanium type yellow pigments - Yellow pigments derived from bismuth, for example, yellow pigments selected from stabilized bismuth vanadate (Py 184 ) - Red pigments, for example, perylene red (e.g., PR149, PR178 and PR224), iron oxide - Bismuth oxyhalide type orange pigments (PO 85 ) - Orange pigments of bismuth vanadate (PO 86 ) - Orange pigments of zinc tin titanium (PO 82 ) - Orange pigments of cerium sulfide (PO 75 ; PO 78 ) - Rutile type antimony titanium chromium orange-yellow pigments (PBr 24 ) - Rutile type tin and zinc orange-yellow pigments (Py 216 ) - Orange-yellow pigments of niobium oxide tin zinc (Py 227 ) - Orange-yellow pigments of composite oxides of tin and niobium - Co3(PO4)2 - LiCoPO4 - CoAl2O4 - Cr2O3 - TiO2 - Black pigment PBk28 (copper chromite black spinel); - And mixtures thereof.

[0198] Decoration According to one embodiment, the layer(s) (3b) is continuous and covers the entire layer (3a) (see Figure 1).

[0199] According to another embodiment, the layer(s) (3b) does not cover the entire layer (3a) and forms at least one decoration (see Figure 2).

[0200] Advantageously, the layer(s) (3b) includes (contains) several decorations, where on the one hand (i) it includes one or more thermochromic pigments, and on the other hand (j) it includes at least one reference temperature pigment composition (see Figure 3).

[0201] 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 are distributed alternately with respect to each other (see Figure 4A).

[0202] According to another embodiment, the two decorations (i) and (j) are partially overlapping. For example, each decoration is represented by different geometric patterns that are uniformly distributed over the entire surface and are partially overlapping (see Figure 4B).

[0203] Preferably, the two decorations (i) and (j) overlap 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).

[0204] 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. Mica or silica flakes coated with titanium dioxide. The flakes that can be used in the context of the present invention can be processed to give specific color effects.

[0205] Advantageously, the flakes are particles selected from the group consisting of mica, aluminum, particles of mica coated with titanium dioxide, or mixtures thereof.

[0206] Holographic flake Advantageously, the flakes are holographic flakes, i.e., a mixture of magnetizable particles and non-magnetizable particles.

[0207] The magnetizable particles may advantageously be particles containing at least one ferromagnetic metal. These magnetizable particles may have a uniform nature, i.e., be composed of the same material, or a composite nature, which means that these magnetizable particles have a core-shell structure in which the ferromagnetic metal is located within 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, flakes made of a plastic material coated with iron oxide Fe2O3, or flakes having a core of ferromagnetic metal and a shell formed of a plastic material or a sol-gel material, as protection against corrosion during the coating process.

[0208] According to one embodiment, some of the magnetizable particles are oriented to form a three-dimensional decoration.

[0209] Advantageously, the mixture of magnetizable particles and non-magnetizable particles is present in an amount of 1% to 5% by weight, preferably 2% to 3% by weight, of the weight of the layer.

[0210] Advantageously, the proportion of non-magnetizable particles in the mixture of magnetizable particles and non-magnetizable particles is constituted by 15% to 40% by weight relative to the total weight of the mixture of magnetizable particles and non-magnetizable particles.

[0211] Advantageously, the magnetizable particles have a size D50 of 23 μm or less.

[0212] For the purposes of the present invention, the term "D50" is understood to mean the maximum dimension indicated by 50% of the particles by number.

[0213] Advantageously, the non-magnetizable particles have a size D90 that is between 20% and 250% of the size D90 of the magnetizable particles.

[0214] For the purposes of the present invention, the term "D90" is understood to mean the maximum dimension indicated by 90% of the particles by number.

[0215] Advantageously, the magnetizable particles and / or the non-magnetizable particles are colored on the surface.

[0216] Advantageously, the non-magnetizable particles are constituted by mica, aluminum, or mica coated with titanium dioxide Advantageously, the magnetizable particles are constituted by iron, iron oxide, iron-coated aluminum, or iron-coated mica, and the iron is in the form of ferrite.

[0217] Preferred embodiment Advantageously, the present invention relates to a coated cooking element (1) for cooking utensils or electric cooking appliances, comprising a metal substrate (2) coated on at least one surface (2a) with the following layers stacked in this order from the metal substrate (2): (3a) A secondary adhesive layer comprising: one or more polymers (α) selected from the group consisting of polyaryl ether ketone (PAEK), accounting for 20 wt% to 100 wt% of the total weight of the secondary adhesive layer; and one or more polymers selected from the group consisting of polyetherimide (PEI), polyimide (PI), polyamideimide (PAI), and polybenzimidazole (PBI), with the weight ratio of PAEK:(PEI + PI + PAI + PBI) being 1:1 to 15:1; (3b) Optionally, one or more 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; (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 - flakes.

[0218] The thickness of the secondary adhesive layer (3a) is preferably configured to be between 30 and 60 μm.

[0219] Preferably, the colorant in the intermediate layer(s) (3b) includes pigment and / or flakes, preferably holographic.

[0220] According to a variant, the intermediate layer(s) (3b) comprises · one or more colorants, especially pigment and / or flakes, preferably holographic; · one or more thermoplastic polymers preferably selected from polyamideimide (PAI), polyimide (PI), polyetherimide (PEI), polybenzimidazole (PBI), polyether sulfone (PES), polyphenylene ether sulfone (PPSU), polyaryl ether ketone (PAEK), and mixtures thereof; · 0 to 10% filler; · 0 to 20% additive; · Optionally, it consists of one or more silicone resins.

[0221] According to another modification, the intermediate layer(s) (3b) is / are · One or more colorants, in particular pigments and / or flakes, preferably holographic; · 0 to 10% filler; · 0 to 20% additive; · One or more silicone resins; and · Optionally, one or more thermoplastic polymers preferably selected from polyamide-imide (PAI), polyimide (PI), polyetherimide (PEI), polybenzimidazole (PBI), polyethersulfone (PES), polyphenylene ether sulfone (PPSU), polyaryl ether ketone (PAEK), and mixtures thereof.

[0222] According to a specific modification, the intermediate layer(s) (3b) does not contain a silicone resin.

[0223] According to another specific modification, the intermediate layer(s) (3b) is / are · One or more colorants, in particular pigments and / or flakes, preferably holographic; · One or more thermoplastic polymers preferably selected from polyamide-imide (PAI), polyimide (PI), polyetherimide (PEI), polybenzimidazole (PBI), polyethersulfone (PES), polyphenylene ether sulfone (PPSU), polyaryl ether ketone (PAEK), and mixtures thereof; · 0 to 10% filler; · 0 to 20% additive; · One or more silicone resins.

[0224] According to certain embodiments, the coating includes two intermediate layers (3b), at least one of which is decorative. Advantageously, the layer(s) (3b) consists of several decorations, one (i) of which contains one or more thermochromic pigments and the other (j) contains at least one reference temperature pigment composition.

[0225] Typically, the thickness of the intermediate layer(s) (3b) is configured to be between 3 μm and 10 μm.

[0226] Preferably, when present, the intermediate layer(s) (3b) only partially covers the base layer (3a).

[0227] Alternatively, according to another embodiment, the coating does not have an intermediate layer (3b). In this case, the layer (3c) is applied to the layer (3a) or the last layer (3ab).

[0228] According to one embodiment, the finishing layer (3c) is composed of one or more silicone resins and optionally one or more thermoplastic polymers.

[0229] According to another embodiment, the finishing layer (3c) is composed of one or more silicone resins and one or more thermoplastic polymers.

[0230] Typically, the thickness of the layer (3c) is configured to be between 0.1 μm and 10 μm.

[0231] In certain embodiments, the average thickness of the adhesion assisting layer (3a) is configured to be between 30 and 60 μm, the thickness of the layer (3b) is configured to be between 3 μm and 10 μm, and the thickness of the layer (3c) is configured to be between 0.1 μm and 10 μm.

[0232] The average thickness of the adhesion assisting layer (3a) is, for example, the average of at least 10 measurements, preferably 15 measurements, of the thickness at 10, respectively 15, random positions.

[0233] Method The present invention also relates to a method for manufacturing a coated cooking element (1) according to the invention, comprising the following successive steps: i. Supplying a metal substrate (2) comprising two opposite faces; ii. Optionally, treating the face (2a) of the substrate (2) to obtain a treated face (2a) that promotes the adhesion of an adhesion-promoting layer (3a) to the substrate (2); iii. Depositing one or more successive layers of the bonding auxiliary layer (3a) onto the face (2a) of the substrate (2); iv. Optionally, drying and / or sintering at a temperature above 400 °C; v. Optionally, applying layers (3ab) and / or intermediate layers (3b); vi. Applying a finishing layer (3c); vii. Curing at a temperature between 230 °C and 420 °C.

[0234] Advantageously, the steps of the method according to the invention make it possible to coat the metal substrate (2) with a coating (3) formed by the layer (3a), optionally the layer (3ab), and also (3b), and (3c). Generally, these layers are wet during their application. For the purposes of the present invention, a "wet layer" is understood to mean that the layer contains all or part of its solvent.

[0235] Preferably, all or part of the solvent of the wet layer is removed naturally or by physical treatment, such as heat drying, air drying, or vacuum treatment.

[0236] Advantageously, the coating composition according to the invention may also contain at least one solvent. Advantageously, the solvent may be protic. Advantageously, the solvent may be non-toxic.

[0237] The solvent that can be used in the coating composition according to the present invention may advantageously contain at least one alcohol, and preferably may be selected from isopropanol, methanol, ethanol, and mixtures thereof.

[0238] The coating is applied to several layers. In this case, the deposition of at least one layer of the coating (3) according to the present invention on at least one of the two opposite surfaces of the substrate is repeated several times. Preferably, a drying step is carried out between the application of each layer, and the coated substrate is cured after the application of the last layer. The application of the coating (3) to the substrate (2) by the method according to the present invention makes it possible to obtain a thermally stable coating layer.

[0239] The applied coating formulation is generally in an aqueous form, and the polymer in the polymer phase is in the form of a suspension. Other non-aqueous solvents may also be suitable.

[0240] Advantageously, the method for manufacturing the coated cooking element (1) according to the present invention includes one or more drying steps between 80 and 150 °C after the application of each layer. Drying can be carried out by convection or infrared rays.

[0241] The coating according to the present invention can be applied by the method according to the present invention on a flat substrate, or on a shaped substrate, or on a locally flat area of a shaped substrate. A thermally stable coating layer is obtained. Generally, this coating layer is wet.

[0242] Advantageously, the method for manufacturing the coated cooking element (1) according to the present invention includes a step of shaping the metal substrate (2) before step iii, after step vi, or after the curing step vii. Shaping is also called stamping.

[0243] If the shaping step precedes the step iii of applying the coating, the coating is preferably carried out by spraying.

[0244] If this shaping step follows step vii of applying the coating, the coating is preferably applied by screen printing or roller printing.

[0245] The method according to the invention comprises step vii of curing the elements obtained in step vi of the method. For the purposes of the present invention, curing the coated substrate not only enables densification of the coating layer applied to the substrate, but is understood to mean a heat treatment that enables crosslinking of the organopolysiloxane precursor (silicone resin).

[0246] Curing is carried out in step vii. Generally, the curing temperature in step viii is composed of 230 °C to 420 °C.

[0247] Advantageously, the method for manufacturing the coated cooking element (1) according to the invention comprises a single final curing step vii among all the coating layers. This single curing step is carried out simultaneously for all the applied layers.

[0248] Advantageously, the method for manufacturing the coated cooking element (1) according to the invention comprises a step of shaping the substrate (2) before or after step iii. Shaping is also called stamping.

[0249] Preferably, the metal substrate (2) in step i) is in the form of a disk, preferably a flat disk, and its shaping is carried out after the application of the coating.

[0250] Advantageously, the method according to the invention does not include drying and / or curing steps other than the step of step (vii).

[0251] The application steps (iii) and (vii) and the application step (v) of layer (3ab) can be carried out by electrostatic powder coating, by spraying in a solvent or aqueous phase, by screen printing, by roller printing, or by digital printing.

[0252] The step (v) of applying the intermediate layer(s) (3b) can be carried out by pad printing, screen printing, inkjet printing, or flexographic printing.

[0253] Article The present invention also relates to a cooking utensil (100) comprising a coated cooking element (1).

[0254] According to one embodiment, the cooking utensil (100) has a heating surface (6) intended to be brought into contact with an external heat source, and the heating surface (6) is on the opposite side of a cooking surface (5) intended to be brought into contact with food during cooking.

[0255] Advantageously, the cooking utensil (100) according to the present invention is selected from the group consisting of a saucepan, a frying pan, a skillet, a fondue pot, a raclette, a Dutch oven, a wok, a sauté pan, a crepe maker, a grill, a griddle, a marmite, a cocotte, an electric cooker or an insert for a bread maker, or a food mold.

[0256] The present invention also relates to an electric cooking appliance (200) having a coated cooking element (1) according to the present invention and a heat source (210) configured to heat the coated cooking element (1).

[0257] Advantageously, the electric cooking appliance (200) is selected from the group consisting of an electric crepe maker, an electric raclette, an electric fondue, an electric grill, a hot plate, an electric cooker, a bread maker, an electric pressure cooker, a waffle maker, a rice cooker, and a jam maker.

[0258] The cooking utensil according to the present invention can in particular be a cooking utensil in which one of the two opposite surfaces of the substrate is, optionally, a concave inner surface, intended to be the surface on which food is introduced into or onto the article, and the other surface of the substrate is, optionally, a convex outer surface, intended to be arranged facing the heat source.

[0259] Non-limiting examples of cooking utensils according to the present invention include, in particular, saucepans and frying pans, wok pans and sauté pans, Dutch ovens and marmites, crepe makers, baking molds and sheets, barbecue grills and griddles, food cooking bowls, and other cooking utensils.

[0260] (Example) The objects, aspects, and advantages of the present invention will be better understood from the following description of specific embodiments of the present invention presented as non-limiting examples with reference to the accompanying drawings.

[0261] Of course, the present invention is in no way limited to the illustrative description and the illustrated embodiments. Modifications are possible while remaining within the scope of protection of the present invention, particularly from the perspective of the configuration of various elements or by substitution of technical equivalents.

[0262] Examples of embodiments: Raw materials of layer (3a): - Heterocyclic polymer resin: · Polyamide-imide resin (PAI) with a solid content of 29% in N-butylpyrrolidone (NBP), · Resin in powder form: Polyamic acid having a 90% dry extract in N-methylpyrrolidone (NMP / water), reference from Solvay, TORLON AI10LS grade, · Resin in solvent: 9% polybenzimidazole (PBI) in dimethylacetamide (DMAc).

[0263] - Other aromatic polymer resins: · Polyetheretherketone (PEEK) resin powder, Vicote 704 made by VICTREX, polymer powder having a d50 of 10 μm, · PEKK resin powder, KEPSTAN 7002PT made by ARKEMA having a d50 of 20 μm, · PEKK resin powder, KEPSTAN 6002PT made by ARKEMA having a d50 of 50 μm; · Polyethersulfone (PES) powder resin, micronized grade from SOLVAY, polymer powder with a d50 of 40 μm.

[0264] - Fluoropolymer resin (pre-dispersed 20% in PPG using UltraTurrax, 20,000 rpm): · 3M's PTFE powder / DYNEON: TF9207Z, · 3M's FEP powder / DYNEON: 6233PZ.

[0265] - Unlabeled polar aprotic solvents (i.e., non-toxic as defined in the present invention): · N-Formylmorpholine (NFM), · N-Methylimidazole (NMI), · N-Butylpyrrolidone (NBP).

[0266] - Alcohol solvents · Propylene glycol: PPG, · Diethylene glycol: butyl diglycol.

[0267] - Surfactants and defoamers; · Tego foamex K7 from Evonik, · Genapol X089 from Clariant.

[0268] - Reinforcing fillers: · Alumina, CAHP-F240 grade (particle size d50: 50 μm); · Silicon carbide, grades SIKA 400, SIKA 320, · Fired silica, · MICA MILL200 / 325.

[0269] - Pigments: · Black 100, · Blue CM13, · Red brick perylene (wear indicator) · Titanium · Talc · Graphite.

[0270] - Acrylic resin: · Modarez PW336: 30% acrylic polymer solution in aqueous phase, · Rohagit SD 15: 30% acrylic polymer solution in aqueous phase.

[0271] Raw materials for the intermediate layers (3b and 3b') and the finish layer (3c): - Silicone resin · RS1: Ethoxy-functionalized polyester silicone resin (80% silicone / 20% polyester) in solvent phase, viscosity at 25°C is about 2000 mPas, solid content = 75%; · RS2: Ethoxy-functionalized polyester silicone resin (50% silicone / 50% polyester) in solvent phase, viscosity at 25°C is about 2000 mPas, solid content = 75%; · RS3: Ethoxy-functionalized polyester silicone resin (30% silicone / 70% polyester) in solvent phase, viscosity at 25°C is about 2000 mPas, solid content = 75%; · RS4: Methylphenyl-functionalized polyester silicone resin in solvent phase, viscosity at 25°C is about 2000 mPas, solid content = 75%; · RS5: Methoxy-functionalized polyester silicone resin (50% silicone / 50% polyester) in solvent phase, viscosity at 25°C is about 2000 mPas, solid content = 75%; · RS6: Ethoxy-functionalized methyl organic polysiloxane resin in aqueous emulsion, viscosity at 25°C is about 1500 mPas, solid content = 52%; - Heterocyclic polymer resin: · Polyamide-imide resin (PAI) with 29% solid content in N-butylpyrrolidone (NBP), Solvay's Torlon.

[0272] - Other aromatic polymer resins: · Polyetheretherketone (PEEK) resin powder, Vicote 703 made by VICTREX, polymer powder with d50 of 25μm, · Polyetheretherketone (PEEK) resin powder, Vicote 704 made by VICTREX, polymer powder with a d50 of 10 μm, · PEKK, KEPSTAN 7002PT resin powder made by ARKEMA, 20 μm d50); · PEKK, Arkema's KEPSTAN 6002PT resin powder with a d50 of 50 μm; · Polyethersulfone (PES) powder resin, micronized grade made by SOLVAY, polymer powder with a d50 of 40 μm.

[0273] - Alcohol solvent; · Dipropylene glycol n-butyl ether (DPNB); · 2-Methoxy-1-methylethyl acetate (MPA); · Butyl glycol acetate (BGA); · Butyl acetate

[0274] - Surfactant and defoamer; · Mineral oil: Evonik's Tego formex K7, · Fatty alcohol polyglycol ether: Gnapol X080 of Clariant or Tefgitole TMN-100X,

[0275] - Reinforcing filler, · Pyrogenic silica: Levasil CC301, · Post-treated dimethyldichlorosilane fumed silica: AEROSIL R972,

[0276] - Pigment · Mica: Iriodin 100 or Iriodin 300 and / or Magnaparl 5000, · Cr / Fe oxide: Sicopal black K0098FK, · Carbon black: Derussol F25 or Cabot Monarch4750, · Perylene red: Parogen red (PR178) · Iron(III) oxide: Brick H856,

[0277] - Acrylic resin: · Rohagit SD 15: 30% acrylic polymer solution in the aqueous phase

[0278] - Silicone oil · Polyether-modified polysiloxane: TEGO GLIDE 100, · Polydimethylsiloxane oil: CT601M.

[0279] - Other additives · AMP90: Solution of 2-amino-2-methyl-1-propanol: 90% polymer in the aqueous phase, buffer, · Metolat368: Fatty acid ester, · Dolfynox 1030: Propoxylated polyglycol ether, wetting agent, · Edaplan LA451: Anionic ester in ethanol / water, wetting agent, · Tego Glide407: Methylphenylpolysiloxane, flow agent.

[0280] Operating principle of Jarmill (mechanical grinding) The ball mill consists of putting the sample to be ground and the so-called mill balls into a bottle and rotating the bottle around its axis at a constant speed. The jar is usually rotated using a roller machine. The sample may be dried and ground, or may be dispersed in a suitable solvent (e.g., water or alcohol). The dispersion may also contain specific adjuvants (such as dispersants or defoamers).

[0281] The average diameter of the milling balls must be adapted to the size of the particles to be ground. The finer the particles, the smaller the diameter of the balls to be used. The total volume of the balls, including the voids between them, is present at about 50 - 60% of the internal volume of the bottle. Balls of different sizes are advantageously distributed according to the following weight ratios in relation to the total weight of the balls: 25% small balls, 50% medium-sized balls, and 25% large balls. The size of the smallest balls is 2 - 10 mm. As materials for the balls, alumina and stabilized zirconia are commonly used.

[0282] Examples of embodiments of cooking utensils according to the present invention: On an aluminum disk (30 cm in diameter) of a shape previously degreased and sandblasted to obtain a roughness of 4 - 7 μm (Ra), a continuous layer 3a selected from the base layer compositions (3a1 - 3a4) is deposited by spraying as described below.

[0283] Layer 3a: Layer 3a1: An aqueous semi-finish composition SF1 based on a heterocyclic polymer having an amine and an unlabeled polar aprotic solvent is prepared.

[0284] An aqueous semi-finish composition SF1 containing the following compounds is prepared, and their respective amounts are shown below:

[0285] [Table 2]

[0286] The implementation of PAI includes a step that passes through the aqueous phase via the production of polyamide-amic acid salt. This step is carried out at room temperature in the presence of an amine using a ball mill of the Discontimill (registered trademark) brand.

[0287] The properties of the aqueous composition SF1 thus obtained are as follows. - Theoretical dry extract: 9.5% - Dry extract measured in the composition: 9.3%

[0288] The preparation of the semi-finished composition SF2 is carried out in a ball mill for 20 minutes to obtain a pulverized paste called SF2 below.

[0289]

Table 3

[0290] Composition of the auxiliary layer 3a1 The last step is carried out with a Rayneri-type disperser to obtain the following adhesion auxiliary layer:

[0291]

Table 4

[0292] The properties of the obtained auxiliary layer 3a1 are as follows: - The final mass ratio of the polymer resin mixture is as follows: PEEK / PAI / PES / filler / acrylic resin / pigment: 19 / 3 / 23 / 30 / 5 / 20 - Theoretical dry extract: 41.1% - Viscosity measured with an AFNOR CA6 cup: 45 seconds

[0293] The thickness of layer 3a1 is configured between 50 μm and 100 μm, preferably between 40 μm and 60 μm.

[0294] Layer 3a2: The preparation of the semi-finished composition SF3 is carried out in a ball mill for 20 minutes to obtain a pulverized paste called SF3 below.

[0295]

Table 5

[0296] Composition of the auxiliary layer 3a2 The last step is carried out with a Rayneri-type disperser to obtain the following adhesion auxiliary layer.

[0297]

Table 6

[0298] The properties of the obtained auxiliary layer 3a2 are as follows. - The final mass ratio of the polymer resin mixture is as follows: PEEK / PAI / PES / filler / acrylic resin / pigment: 17 / 3 / 25 / 30 / 5 / 20 - Theoretically dry extract: 42.4% - Viscosity measured with an AFNOR CA6 cup: 55 seconds

[0299] The thickness of this layer SCD4 of Example 4 is composed of 50 μm to 100 μm, preferably 40 μm to 60 μm.

[0300] Layer 3a3: The preparation of the semi-finished composition SF4 is carried out in a ball mill for 20 minutes to obtain a pulverized paste called SF4 below.

[0301]

Table 7

[0302] Composition of the auxiliary layer 3a3 The final step is carried out with a Rayneri-type disperser to obtain the following hard auxiliary layer.

[0303]

Table 8

[0304] The properties of the obtained auxiliary layer 3a3 are as follows: - The final mass ratio of the polymer resin mixture is as follows: PEEK / PAI / PES / : 75 / 5 / 20 - Theoretically dry extract: 38.5% - Viscosity measured with an AFNOR CA6 cup: 1 minute 40 seconds

[0305] The thickness of this layer SCD6 of Example 6 is composed of 50 μm to 100 μm, preferably 40 μm to 60 μm.

[0306] Layer 3a4: The preparation of the semi-finished composition SF5 is carried out for 20 minutes in a ball mill to obtain a pulverized paste called SF5 below.

[0307]

Table 9

[0308] The formulation of the auxiliary layer 3a4 is carried out with a Rayneri-type disperser to obtain the following hard auxiliary layer.

[0309]

Table 10

[0310] The properties of the obtained auxiliary layer 3a4 are as follows: - The final mass ratio of the polymer resin mixture is as follows: PEEK / PAI / filler / acrylic resin / pigment: 42 / 3 / 30 / 5 / 20 - Theoretical dry extract: 41.0% - Viscosity measured with an AFNOR CA6 cup: 55 seconds

[0311] The thickness of this layer SCD9 of Comparative Example 3 is composed of 50 μm to 100 μm, preferably 40 μm to 60 μm.

[0312] Intermediate layer (3b) Next, a continuous layer (3b) selected from the layer compositions described below is deposited by spraying it onto one of the layer(s) (3a): layer 3b1, layer 3b2, and layer 3b3.

[0313]

Table 11

[0314]

Table 12

[0315]

Table 13

[0316] The aqueous composition of layer 3b is prepared according to the ball milling method. The ball mill is carried out in a bottle as described above. The sample may be dried and pulverized, or may be dispersed in a suitable solvent (e.g., water, alcohol or solvent). The dispersion may also contain certain adjuvants (such as dispersants or defoamers).

[0317] The thickness of this layer 3b is composed between 10 μm and 20 μm, preferably between 12 μm and 15 μm.

[0318] Intermediate layer (3b') and finish layer (3c) The substrate to which the base layer (3a) and the continuous layer (3b) are applied as described above is coated with a multi-layer non-stick coating composed of an intermediate layer 3b' (6 - 8 μm) and a finish layer 3c (14 - 18 μm) dried at 100 °C for 4 minutes. The whole is finally heated at 250 °C for 1 hour, that is, the process includes only one curing step after the deposition of various layers.

[0319] The composition of the intermediate layer 3b' is deposited by spraying and is as described below: layer 3b'1 and layer 3b'2:

[0320]

Table 14

[0321]

Table 15

[0322]

Table 16

[0323] The composition of the finishing layer (3c) is deposited by spraying and is described below: Layers 3c1 to 3c10:

[0324]

Table 17

[0325]

Table 18

[0326]

Table 19

[0327]

Table 20

[0328]

Table 21

[0329]

Table 22

[0330]

Table 23

[0331]

Table 24

[0332]

Table 25

[0333]

Table 26

[0334] Characteristic evaluation method of anti-burning coating: Egg performance test The method for evaluating the properties of the anti - adhesion coating is carried out using an egg test conforming to AFNOR NF D21 - 511 paragraph 3.3.2 and is implemented as follows.

[0335] Wash the sample and wipe the remaining water from the surface.

[0336] Pre - dry the inner surface of the container body.

[0337] The cooking container is heated to a temperature of 140 - 170 °C on a gas stove.

[0338] Break an egg with a 60 / 65 caliber, pour it into the center of the hot cooking container, and coagulate the egg (6 - 9 minutes). Take the egg out of the cooking container with a spatula, wash the coating with a wet plant - based sponge, evaluate the anti - adhesion properties of the cooking container by this action, and then record: Grade 100: The egg can be completely removed with a plastic spatula. Grade 75: The egg is not completely removed, but the coating can be easily washed with a wet sponge. Grade 50: The egg is not completely removed, but the coating can be washed with a wet sponge. Grade 25: The egg is not completely removed, and the coating cannot be washed with a wet sponge. Grade 0: The egg is not removed, and the coating cannot be washed with a wet sponge.

[0339]

Table 27

[0340] All coatings according to the invention based on silicone polyester resins have good non-stick properties while adhering to metals.

Claims

1. A coated cooking element (1) for cooking utensils or electric cooking appliances, comprising a metal substrate (2) coated in this order from said metal substrate (2) with at least the following layers on at least one surface (2a), said layers being (3a) an adhesion-promoting layer, wherein 20% to 100% by weight of the total weight of the auxiliary layer is one or more polymers (α) selected from the group consisting of polyaryl ether ketone (PAEK), and one or more polymers selected from the group consisting of polyetherimide (PEI), polyimide (PI), polyamideimide (PAI) and polybenzimidazole (PBI), and the weight ratio of PAEK:(PEI + PI + PAI + PBI) is 1:1 to 15:1, an adhesion-promoting layer; (3b) Optionally, one or more 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, an intermediate layer consisting of (3c) a finishing 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 - flakes, a finishing layer, the coated cooking element (1).

2. The coated cooking element (1) according to claim 1, wherein the adhesion-promoting layer (3a) comprises one or more polymers (β) selected from the group consisting of polyphenylene sulfide (PPS) and polyethersulfone (PES).

3. The coated cooking element (1) according to claim 2, wherein the adhesion-promoting layer (3a) comprises one or more polymers (β) selected from the group consisting of polyphenylene sulfide (PPS) and polyethersulfone (PES) in an amount of at least 20% by weight, preferably at least 25% by weight, of the total weight of the auxiliary layer.

4. The coated cooking element (1) according to any one of claims 1 to 3, wherein the adhesion-promoting layer (3a) occupies less than 40% by weight, preferably less than 30% by weight, preferably 5 to 25% by weight of the total weight of the filler auxiliary layer.

5. The filler of the adhesion auxiliary layer (3a) is selected from the group consisting of metal oxides, metal carbides, and metal nitrides, and is preferably alumina, silicon carbide, or pyrogenic silica, for the coated cooking element (1) according to claim 2.

6. The adhesion auxiliary layer (3a) contains one or more acrylic resins, for the coated cooking element (1) according to any one of claims 1 to 5.

7. The adhesion auxiliary layer (3a) contains one or more colorants, for the coated cooking element (1) according to any one of claims 1 to 6.

8. The polyaryletherketone (PAEK) is selected from the group consisting of polyetherketone (PEK), polyetheretherketone (PEEK), polyetherketoneketone (PEKK), polyetheretherketoneketone (PEEKK), and polyetherketoneetherketoneketone (PEKEKK), for the coated cooking element (1) according to any one of claims 1 to 7.

9. The polymer is selected from the group consisting of polyetheretherketone (PEEK) and polyamideimide (PAI), for the coated cooking element (1) according to any one of claims 1 to 8.

10. The colorant is selected from the group consisting of thermochromic pigments, thermally stable pigments, flakes, preferably holographic flakes, and mixtures thereof, for the coated cooking element (1) according to any one of claims 1 to 9.

11. The thermochromic pigment is Bi ２ O ３ 、Fe ２ O ３ 、V ２ O ５ 、WO 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 selected from the group consisting of - x is equal to 0, or x is composed between 0.001 and 0.999; - y is equal to 0, or is composed 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, for the coated cooking element (1) according to claim 10.

12. The thermally stable pigment is - rutile type yellow pigment, - A yellow pigment derived from bismuth, for example, a stabilized bismuth vanadate (Py １８４ ) and a yellow pigment selected therefrom, - a red pigment, for example, perylene red (e.g., PR １４９ , PR １７８ and PR ２２４ ), iron oxide, selected from; - Orange pigment of the oxyhalide bismuth type (PO ８５ ) - Orange pigment of bismuth vanadate (PO ８６ ); - Orange pigment of zinc tin titanium (PO ８２ ); - Orange pigment of cerium sulfide (PO ７５ ; PO78); - Rutile - type antimony titanium chromium orange - yellow pigment (PBr ２４ ) - Rutile type orange-yellow pigments of tin and zinc (Py ２１６ ) ; - Orange-yellow pigment of niobium oxide tin zinc sulfide (Py ２２７ ) ; - orange yellow pigment of a composite oxide of tin and niobium. -Co ３ (PO ４ ) ２ , -LiCoPO ４ ; -CoAl ２ O ４ ; -Cr ２ O ３ ; -TiO ２ ; - black pigment PBk28 (copper chromite black spinel); - and mixtures thereof, and is selected from the group consisting of, for the coated cooking element (1) according to claim 10 or 11.

13. The coated cooking element (1) according to any one of claims 10 to 12, wherein the holographic flakes are a mixture of magnetizable particles and non-magnetizable particles.

14. The coated cooking element (1) according to any one of claims 1 to 13, wherein the metal substrate (2) is a substrate made of aluminum, stainless steel, cast iron or cast aluminum, iron, titanium or copper.

15. The coated cooking element (1) according to any one of claims 1 to 14, wherein the finishing layer (3c) contains one or more thermoplastic polymers, and the proportion of the thermoplastic polymer in the layer (3c) is less than 50%, preferably less than 40%.

16. The coated cooking element (1) according to any one of claims 1 to 15, wherein the thickness of the layer (3a) is 10 μm to 100 μm, preferably 20 μm to 80 μm, more preferably 30 μm to 60 μm.

17. A method for manufacturing the coated cooking element (1) according to any one of claims 1 to 16, comprising the following steps: i. Supplying a metal substrate (2) including two opposite surfaces; ii. Optionally, treating the surface (2a) of the substrate (2) to obtain a treated surface (2a) that promotes the adhesion of the adhesion assisting layer (3a) to the substrate (2); iii. Depositing one or more continuous layers of the bonding assisting layer (3a) on the surface (2a) of the substrate (2); iv. Optionally, drying and / or sintering at a temperature exceeding 400°C; v. Optionally, applying layer(s) (3ab) and / or intermediate layer(s) (3b); vi. Applying a finishing layer (3c); vii. Drying at a temperature of 230°C to 420°C.

18. The method according to claim 17, wherein the sintering temperature is from 400°C to 440°C.

19. A cooking utensil (100) comprising the coated cooking element (1) according to any one of claims 1 to 16.

20. The cooking utensil (100) according to claim 19, having a heating surface (6) intended to be brought into contact with an external heat source, and the heating surface (6) is on the opposite side of a cooking surface (5) intended to be brought into contact with food during cooking.

21. The cooking utensil (100) according to claim 19 or 20, selected from the group consisting of a source pan, a frying pan, a skillet, a fondue pot or a raclette pan, a Dutch oven, a wok, a sauté pan, a crepe maker, a grill, a griddle, a marmite, a cocotte, an electric cooker or an insert for a bread maker, or a food mold.

22. An electric cooking appliance (200) having a coated cooking element (1) according to any one of claims 1 to 16 and a heat source (210) configured to heat the coated cooking element (1).

23. The electric cooking appliance (200) according to claim 22, selected from the group consisting of an electric crepe maker, an electric raclette, an electric fondue, an electric grill, a hot plate, an electric cooker, a bread maker, an electric pressure cooker, a waffle maker, a rice cooker, and a jam maker.

Images