Non-fluorinated Hybrid PEAK / Silicone Resin Coating

Abstract

The present invention relates to a coated cooking element (1) for cooking utensils or electric cooking appliances, comprising a metal substrate (2) starting from which, in this order, at least one surface (2a) is coated with at least the following layers: (3a) a porous hard auxiliary layer consisting of one or more polyetherarylketones (PEAK) and their mixtures, optionally a filler, optionally an additive of less than 3% by weight relative to the weight of the hard auxiliary layer, and optionally a colorant of less than 3% by weight relative to the weight of the hard auxiliary layer; (3b) one or more optional intermediate layers consisting of 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 finishing layer consisting of one or more silicone resins and optionally - one or more thermoplastic polymers, and / or - one or more fillers, and / or - one or more additives, and / or - flakes. It also relates to a method for manufacturing the same cooking utensils or cooking appliances containing the same.

Description

Technical Field

[0001] The field of the present invention is cooking utensils coated by coating on one of those surfaces, more precisely, cooking utensils coated with a silicone resin-based coating of these items.

Background Art

[0002] In the field of cooking utensils, fluoropolymer-based coatings, especially polytetrafluoroethylene (PTFE), are generally known for their anti-adhesion and heat resistance properties.

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

[0004] Patent Document 1 (International Publication No. 2020 / 144051) relates to a fluoropolymer-based coating, and by incorporating organic (SiC) and mineral (Al2O3) fillers into the primary and finish layers of the coating, the mechanical resistance to wear is improved.

[0005] The improvement in performance achieved regarding mechanical strength is satisfactory but still not optimal.

[0006] Fluoropolymer-based coatings are mainly intended for pots and frying pans, but in the field of molding (molds, cake pans, waffle makers, etc.) or small household appliances (rice cookers, fryer containers, electric crepe makers), there may be other applications due to their stampability.

[0007] The alternative to PTFE coating consists of the use of so-called "ceramic" coatings developed by the sol-gel process and the use of tetraethyl orthosilicate (Patent Document 2 (European Patent No. 2806776)). These coatings have specific properties of being hard and resistant to mechanical wear, but also exhibit brittle behavior and low non-adhesion compared to fluoropolymer-based coatings.

[0008] Furthermore, these coatings lack punch-out properties and are therefore not very suitable for molding and small household appliances.

[0009] In the field of molding (for the general public or industrial molding), the heat resistance constraints are low (up to 220 °C), enabling the use of other types of coatings such as silicone coatings, so fluoropolymer-based coatings are not very widespread.

[0010] Pure silicone resins are described as having anti-adhesion properties and being resistant to temperatures exceeding 220 - 230 °C. On the other hand, they are considered to adhere poorly to the substrate.

[0011] On the other hand, silicone polyester resins adhere to the substrate and are suitable for punch-out processing. Since they have anti-adhesion properties, they are very widely used in molding. However, they decompose at temperatures exceeding 230 °C. More specifically, cooking utensils are used in the temperature range of 50 - 250 °C, and in the case of articles with an induction bottom, it is not surprising to reach temperatures of 300 °C and even 350 °C. Therefore, their use is not compatible with the operating temperatures in the field of cooking utensils.

Prior Art Documents

Patent Documents

[0012]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0013] The present invention addresses the technical problem of improving the scratch resistance and chip resistance of silicone coatings through the production of an auxiliary layer in contact with a metal substrate based on a mixture of thermoplastic and / or thermally stable polymers having high thermomechanical properties.

[0014] To significantly improve the scratch resistance of silicone coatings, the inventors have shown that it is possible to produce a macroporous auxiliary layer having a formulation suitable for thermally fusible resins, which is sprayed by thermal spraying onto a metal substrate without preheating above 100°C and then one or more layers of a liquid silicone coating are directly applied by conventional air pressure spraying. The presence of reinforcing fillers (such as alumina, silicon carbide, etc.) is also possible in the auxiliary layer.

[0015] The production of this “composite material” in which silicone is strongly fixed in the matrix of the polymer auxiliary layer produces a final coating with significantly improved mechanical properties.

[0016] This coating has excellent adhesion performance due to the good bonding between the first PEEK-based layer and the coating layer.

[0017] The present invention enables the production of an overall layer of high thickness without causing cracking and crazing.

[0018] It has excellent scratch resistance and resistance to mechanical shock. The present invention enables obtaining excellent scratch resistance performance while maintaining a method with a single final curing, which is industrially and economically viable.

[0019] The scratch resistance and impact resistance are significantly improved, and the use of metal utensils does not cause significant damage.

[0020] Therefore, consumers own more durable items with coatings that more effectively prevent direct contact between food and the substrate (such as improved durability with anti-adhesion performance, improved stability when in contact with aluminum, improved aesthetics, etc.).

[0021] This method is inexpensive and robust, involving only one final curing at a temperature below 400 °C without preheating or drying at high temperatures.

[0022] Therefore, a coating that is more robust when facing mechanical stress also has improved durability from the perspectives of anti-adhesion, stain prevention, and corrosion resistance.

[0023] Patent Document 3 (European Patent No. 2319631) describes the development of a two-layer silicone resin-based coating combined with a 0.5 - 20% high-temperature thermoplastic material (base layer), which is mechanically strong, adheres to the substrate, and enables obtaining an anti-adhesive coating. The properties of the thermoplastic resin vary between the base layer (PEEK) and the finish layer (PPS), and it is mainly located in the substrate layer to ensure adhesion to the substrate. This patent does not describe a temperature indicator.

[0024] Patent Document 4 (U.S. Patent Application Publication No. 2022 / 0073785) proposes a two-layer silicone / thermoplastic coating structure much more concentrated in thermoplastic materials and does not explain the incorporation of a colored indicator based on a thermochromic pigment.

Means for Solving the Problems

[0025] The 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 on at least one surface (2a) by at least the following layers in this order, starting from the metal substrate (2). (3a) A porous hard auxiliary layer comprising one or more polyether aryl ketones (PEEK) and their mixtures, an optional filler, optionally an additive of less than 3% by weight based on the weight of the hard auxiliary layer, and optionally a colorant of less than 3% by weight based on the weight of the hard auxiliary layer. (3b) One or more optional intermediate layers comprising one or more colorants and optionally - one or more silicone resins, and / or - one or more thermoplastic polymers, and / or - one or more fillers, and / or - one or more additives comprising one or more intermediate layers. (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 comprising a finishing layer.

[0026] Another object of the present invention relates to a method for manufacturing a coated cooking element (1) according to the present invention, the following consecutive steps a) Supplying a metal support (2) having two opposite surfaces; b) Optionally, treating the surface (2a) of the support (2) to obtain a treated surface (2a) that promotes the adhesion of the hard auxiliary layer (3a) onto the support (2). c) By means of a thermal spray onto the inner surface (2a), there is produced on the inner surface (2a) an adhesive hard auxiliary layer (3a) of one or more polyether aryl ketones (PEAK) and their mixtures in powder or dispersion form, optionally a filler, optionally an additive of less than 3% by weight relative to the weight of the hard auxiliary layer (3a), and optionally a colorant(s) of less than 3% by weight relative to the weight of the hard auxiliary layer (3a). d) Optionally, a step of drying and / or curing. e) Optionally, a step of applying one or more layers (3ab) and / or one or more intermediate layers (3b). f) A step of applying a finishing layer (3c). g) A step of drying and / or curing. It includes.

[0027] Another object of the present invention relates to a cooking utensil (100) comprising a coated cooking element (1) according to the present invention.

[0028] 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) designed to heat the coated cooking element (1).

[0029] Definition The term "layer" should be understood in the context of the present invention as a continuous layer or a discontinuous layer. A continuous layer (also called a monolithic layer) is a single entity that forms a complete plane covering the surface onto which it is applied completely.

[0030] The term "discontinuous" shall mean a layer that does not have a uniform thickness over the entire surface on which it is deposited. The coverage may not be present at a particular location.

[0031] The terms "base layer", "primer layer", "adhesive layer" or "adhesive primer" shall mean all layers from the first layer directly applied to the support (which layer preferably adheres well to the support and contributes all its mechanical properties (hardness, scratch resistance) to the coating) to the last layer before the first decorative layer.

[0032] The term "finish layer" or "finish" shall mean a continuous transparent surface layer which protects the decorative layer from mechanical attack and allows complete visualization of the decorative layer while imparting anti - adhesion properties to the coating.

[0033] Preferably, the last finish layer is intended to come into contact with food.

[0034] The term "decoration" or "decorative layer" shall mean one or more continuous or discontinuous layers containing a pigment composition. The decoration can be in the form of one or more patterns having one or more colors. The decoration is clearly visible to the user with the naked eye and at the conventional distances of use of household articles.

[0035] The term "overlapping layer" shall mean a layer that is partially or fully superimposed. These layers may be in the form of a partially overlapping pattern, for example, in the form of concentric discs.

[0036] The term "adjacent layer" shall mean a layer that is not superimposed. These layers can be in the form of the same or different patterns that are not superimposed and are preferably uniformly distributed.

[0037] The term "reference temperature pigment composition" shall mean a composition containing pigments that can indicate, at a given temperature, that the optimum temperature for use by the user has been reached. This indication is made by comparing the color of the thermochromic pigment composition with the color of the reference temperature pigment composition. It is either the case that the optimum temperature for use is reached when the colors are the same or the case that the optimum temperature for use is reached when the colors are visually very different.

[0038] The "reference temperature pigment composition" can include pigments having the following. - At the optimal use temperature, 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 ambient temperature and does not change color with temperature, so * Or, at ambient temperature, this pigment has a color different from that of the thermochromic pigment composition that changes to the same color as the thermochromic pigment composition at the optimal use temperature, so - Regardless of whether this pigment changes color with temperature changes, a color very different from that of the thermochromic pigment composition at the optimal use temperature.

[0039] The optimal use temperature can be reached 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 scale supplied to the user together with the said article.

[0040] The reference temperature pigment composition is thermochromic or thermally stable.

[0041] The reference temperature pigment composition may be, for example, a reference cooking temperature pigment composition or for indicating the risk of overheating.

[0042] The present invention has at least one of the following advantages. - The coating according to the present invention has a thermochromic functionality with remarkable visibility, and the color change is contrastive over the targeted temperature range, centered around, for example, near the food cooking temperature for kitchen 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 for limiting occasional overheating that weakens the coating and for safety. - The thermochromic pigment composition has reversible thermochromic properties, i.e., when the temperature decreases, after the color change under the action of heat, the compound returns to its initial state and its initial color, and this color change cycle (reversibility) can be repeated infinitely. - The coating according to the present invention has significant thermal stability when the temperature rises and is stable up to about 450 °C.

[0043] The expression "thermochromic semiconductor" shall be taken to mean, in the context of the present invention, a mineral or organic compound having a reversible color change upon a rise in temperature. The gradual and reversible thermochromism of these semiconductor compounds is related to the decrease in the width of the bandgap of the semiconductor due to the expansion of the material. More specifically, the periodicity of the anion and cation lattice leads to the collection of energy levels into energy bands. The high-energy filled energy band is called the valence band, and the low-energy empty energy band is called the conduction band. There is a forbidden band called the bandgap between these two bands. The color of a semiconductor material can be caused by the presence of a charge transfer (interatomic photon absorption) corresponding to the passage of electrons from the valence band to the conduction band on a given atom, or generally from the orbit of an anion to the orbit of a cation.

[0044] In the field intended for the present invention, optimal conditions are obtained when the coating reaches a temperature suitable for food cooking, preferably 100 - 250 °C.

[0045] In the context of the present invention, the term "thermochromic pigment or pigment composition" should be understood to mean a pigment or pigment composition that changes color as a function of temperature within a given temperature range, and this change is reversible. This color change is visible to the user with the naked eye at conventional distances of use.

[0046] The term "thermally stable pigment" shall mean a pigment that does not exhibit a color change when exposed to a temperature increase within a given temperature range, or a pigment that exhibits a hue change so small that it is not visible to the user with the naked eye and not visible at conventional viewing distances when exposed to a temperature increase within a given temperature range.

[0047] The thermally stable pigment preferably 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.

[0048]

Number

[0049] L1 * , a1 * and b1 * characterize the L * a * b * values of the compound at ambient temperature. L2 * , a2 * and b2 * characterize the L * a * b * values of the compound at 200°C.

[0050] The expression "the colors are the same" shall mean that the user cannot distinguish them with the naked eye at conventional viewing distances.

[0051] The expression "cooking utensils" shall be understood in the context of the present invention as articles for cooking. For this purpose, they are intended to be subjected to heat treatment.

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

[0053] The expression "electric cooking appliance" should be understood in the context of the present invention as a heated object having its own heating system such as an electric crepe maker, an electric raclette appliance, an electric fondue appliance, an electric grill, an electric panini grill, an electric cooking appliance, a bread maker or an electric pressure cooking appliance.

[0054] The term "coating" shall mean all layers that adhere to a metal substrate and cover this substrate. The coating obtained according to the present invention is preferably solid. The term "solid" refers to the property of an adhesive material that is insoluble in water, common solvents, food components such as aqueous or fatty mixtures, even if the material can have a high hardness or a high flexibility like an elastomer.

[0055] The term "silicone resin-based coating" shall mean a coating that contains one or more silicone resins in one or more of its layers.

[0056] The term "equivalent diameter of the pores" shall mean the diameter of a sphere having the same volume as the pores in question.

[0057] The term "average equivalent diameter of the pores" shall mean the average of the equivalent diameters of the pores.

[0058] The term "median of the equivalent diameters of the pores" shall mean the median of the equivalent diameters of the pores. 50% of the pores have an equivalent diameter less than this diameter and 50% have a higher equivalent diameter.

[0059] In the present invention, % by weight is expressed as dry weight, i.e., without solvent.

Brief Description of the Drawings

[0060]

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DETAILED DESCRIPTION OF THE INVENTION

[0061] 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 face (2a) with at least the following layers in this order, starting from the metal substrate (2). (3a) A porous hard auxiliary layer consisting of one or more polyetherarylketones (PEEK) and mixtures thereof, optionally a filler, optionally an additive of less than 3% by weight relative to the weight of the hard auxiliary layer, and optionally a colorant of less than 3% by weight relative to the weight of the hard auxiliary layer. (3b) One or more optional, preferably two 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 comprising one or more intermediate layers, (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 forming a finishing layer.

[0062] Advantageously, layer (3a) and optional (3b) and (3c) form a coating (3) covering the metal substrate (2). This coating (3) has anti-adhesion properties and forms an anti-adhesion coating.

[0063] Advantageously, layer (3a) contacts the metal substrate (2) through one of its surfaces via its surface (2a).

[0064] Accordingly, 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.

[0065] The coating of the cooking element (1) according to the invention does not contain a fluorinated polymer, also called a fluoropolymer. In other words, said coating is either a fluorinated polymer or lacks a fluorinated polymer.

[0066] The coating of the cooking element (1) according to the invention does not contain any fluorinated polymer.

[0067] The coating of the cooking element (1) according to the invention is intended to come into contact with food.

[0068] Advantageously, the finishing layer (3c) contacts the food via one of its surfaces and thus forms the cooking surface (5).

[0069] Advantageously, one or more polyaryl ether ketones (PAEK) are 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 PEEK and mixtures thereof.

[0070] Preferably, the average thickness of the rigid auxiliary layer (3a) is greater than 5 μm, more preferably greater than 15 μm, and particularly preferably 20 to 50 μm. This average is, for example, the average of at least 10 measurements, preferably 15 measurements, of the thicknesses at 10 points and 15 points respectively at random positions.

[0071] Advantageously, the average equivalent diameter of the pores in the rigid auxiliary layer (3a) is greater than 5 μm.

[0072] The porosity data of the rigid auxiliary layer (3a), particularly the overall porosity, the average equivalent diameter of the pores, and the central equivalent diameter of the pores, are measured by X-ray microtomography using a synchrotron source.

[0073] Preferably, the average equivalent diameter of the pores in the rigid auxiliary layer (3a) is greater than 8 μm, more preferably greater than 10 μm.

[0074] Preferably, the central equivalent diameter of the pores in the rigid auxiliary layer (3a) is greater than 6 μm, more preferably greater than 7 μm, and even more preferably greater than 8 μm.

[0075] Preferably, more than 30%, more preferably more than 40%, and particularly preferably more than 50% of the pores in terms of number in the rigid auxiliary layer (3a) have an average equivalent diameter of 10 μm or more.

[0076] Preferably, more than 20%, more preferably more than 30% of the pores in terms of the number in the hard auxiliary layer (3a) have an average equivalent diameter of more than 10 μm and 20 μm or less.

[0077] Preferably, more than 60%, more preferably more than 70%, particularly preferably more than 80% of the pores in terms of the number in the hard auxiliary layer (3a) have an average equivalent diameter of 20 μm or less.

[0078] Preferably, more than 5%, more preferably more than 7%, particularly preferably more than 10% of the pores in terms of the number in the hard auxiliary layer (3a) have an average equivalent diameter of more than 20 μm and 30 μm or less.

[0079] Preferably, the pores in terms of the number in the hard auxiliary layer (3a) have an equivalent diameter of more than 30 μm, and preferably at least 1% of the pores in terms of the number in the hard auxiliary layer (3a) have an equivalent diameter of more than 30 μm.

[0080] Preferably, the hard auxiliary layer (3a) has a surface roughness Ra of 5 μm to 100 μm, more preferably 10 μm to 60 μm.

[0081] Preferably, the hard auxiliary layer (3a) has a developed surface area Sdr of 10% to 100%, preferably 30% to 80%.

[0082] Advantageously, the thickness of the layer (3c) is 0.05 μm to 100 μm, preferably 0.08 μm to 20 μm, particularly preferably 0.1 μm to 10 μm. In a particular embodiment of the invention, the thickness of the layer (3c) is 100 nm + / - 5 nm.

[0083] According to one embodiment, the thickness of the layer (3c) is 0.1 μm to 2 microns (2 μm), preferably 0.2 μm to 1.5 μm.

[0084] 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.

[0085] The coating of the cooking element (1) according to the invention may comprise one or more optional layers (3ab) and may be inserted between one or more layers (3a) and one or more layers (3b), or between one or more layers (3a) and one or more layers (3c), and consists of one or more silicone resins and, optionally, - one or more thermoplastic polymers, and / or - one or more fillers, and / or - one or more additives and is made up of.

[0086] Advantageously, the thickness of one or more layers (3ab), if present, is from 0.05 μm to 100 μm, preferably from 0.08 μm to 20 μm, particularly preferably from 0.1 μm to 10 μm.

[0087] Advantageously, the thickness of layer (3b) is from 1 μm to 100 μm, preferably from 2 μm to 30 μm, particularly preferably from 3 μm to 10 μm.

[0088] Metal substrate Advantageously, said metal substrate (2), also referred to as a support, is a substrate made of aluminum, stainless steel, cast iron or cast aluminum, iron, titanium or copper.

[0089] For the purposes of the present invention, aluminum is to be understood as a metal composed of 100% aluminum or an aluminum alloy.

[0090] Advantageously, the metal substrate (2) is a substrate made of aluminum, stainless steel or a multi-layer metal substrate. The metal substrate (2) may be a two-layer or three-layer substrate, and these multiple layers can be obtained, for example, by co-lamination, thermal diffusion under load (solid bonding), or impact bonding at high or low temperature.

[0091] Preferably, the metal substrate (2) comprises alternating layers of metal and / or metal alloy.

[0092] According to one embodiment, the metal substrate (2) is a substrate made of aluminum or a stainless steel alloy, or a multi-layer metal substrate whose surface (2a) is aluminum or a stainless steel alloy.

[0093] Preferably, the metal substrate (2) is an aluminum substrate.

[0094] Advantageously, the thickness of the metal substrate (2) is from 0.5 mm to 10 mm.

[0095] Advantageously, the surface (2a) of the metal substrate (2) has undergone a prior surface treatment to improve the adhesion of the coating to the substrate.

[0096] 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 peening, physical-chemical plasma, corona or laser treatment, chemical activation, or a combination of these different techniques.

[0097] Advantageously, the surface (2a) of the substrate on which the coating (3) according to the invention is applied can be treated to increase its specific surface area. In the case of an aluminum substrate, this treatment can be carried out by adding materials using techniques such as anodization (creation of a tubular alumina structure), chemical etching, sandblasting, brushing, shot peening, or thermal spraying (flame, plasma or arc spraying). Other metal substrates can also be polished, sandblasted, brushed, microbead blasted, or receive material addition using techniques such as thermal spraying (flame, plasma or arc spraying).

[0098] The metals that can be used as the base material of the present invention are preferably base materials made of aluminum, which may or may not be anodized and are optionally polished, brushed, sandblasted, shot-peened, or microbead-blasted; base materials made of aluminum alloys, which may or may not be anodized and are optionally polished, brushed, sandblasted, or microbead-blasted; base materials made of steel, which are optionally polished, brushed, sandblasted, shot-peened, or microbead-blasted; base materials made of stainless steel, which are optionally polished, brushed, sandblasted, or microbead-blasted; base materials made of cast steel, aluminum, or iron; and base materials made of copper, which are optionally hammered or polished.

[0099] Preferably, the base material can be selected from base materials including a layer of ferritic stainless steel / aluminum / austenitic stainless steel; base materials including a layer of stainless steel / aluminum / copper / aluminum / austenitic stainless steel; cast aluminum lined at the outer bottom of stainless steel; an aluminum or aluminum alloy calotte; a metal co-deposited layer base material, for example, a two-layer co-deposited layer base material including a stainless steel layer (for example, intended to form the inner surface of an article) and a layer of aluminum or aluminum alloy that is anodized or not (for example, intended to form the outer surface of an item).

[0100] Preferably, the arithmetic mean roughness Ra of the surface of the surface (2a) of the metal base material (2) is 1 μm or more.

[0101] The arithmetic mean roughness Ra is measured by a roughness meter in accordance with the standard ISO 4287. Ra represents the arithmetic mean of the deviations from the mean. The surface topography can be studied, in particular, using a profilometer equipped with a fine stylus having a diamond tip, or by an optical measuring instrument of the Altisurf® type which enables non-contact measurement by a confocal chromatic sensor. The study of this surface topography data makes it possible to define the arithmetic mean roughness Ra.

[0102] Silicone resin In the text of this specification, the expression "silicone resin" is used interchangeably to refer to silicone before or after its crosslinking. In the text of this specification, the expression "silicone" refers to organopolysiloxane materials. Crosslinking is a process that enables the conversion of silicone into an insoluble material, for example, by polyaddition, polycondensation, or dehydrogenation. Crosslinking is generally carried out on precursors that are oils or silicone resins, which crosslink to obtain a three-dimensional network of materials that are referred to herein as silicone resins.

[0103] This crosslinking can be carried out by thermal activation or by chemical activation using a catalyst such as platinum, for example.

[0104] Silicone resins can be obtained from precursors that are advantageously soluble in solvents or water or are emulsions, such as crosslinkable oils or resins. Crosslinkable oils or resins are selected in particular from silicone hydrides, silicone oil resins containing at least one vinyl group (-CH=CH2), silicone resins or silicone-polyester resins (copolymers) containing at least one alkoxy group, such as a methoxy or ethoxy group, and / or silicone resins or silicone-polyester resins (copolymers) containing at least one alkoxy group, in particular an ethoxy group or a hydroxy group and mixtures thereof. These precursors have the ability to crosslink to obtain a silicone resin characterized by its insoluble and substantially solid form.

[0105] Advantageously, these precursors are polymers or oligomers, in the form of silicone oils with various degrees of branching, or silicone resins with various degrees of pre-crosslinking, or silicone resin copolymers such as silicone-polyester, silicone-alkyd, silicone-polyurethane or silicone-epoxy resins, or in the form of a mixture of silicone oil, silicone resin and silicone resin copolymer. The silicone atoms can be substituted by alkyl (especially methyl) or aryl (especially phenyl) groups or mixtures thereof. The oil or resin preferably contains one or more (two or more) hydroxy or alkoxy (especially methoxy, ethoxy, butoxy) functional groups as substituents of the silicone atoms.

[0106] Advantageously, one or more silicone resins obtained after crosslinking of these precursors, i.e. after being crosslinked, are selected from the group consisting of methyl silicone resin and / or phenyl silicone resin and / or methyl-phenyl-silicone resin, methyl silicone-polyester resin (copolymer), phenyl silicone-polyester resin (copolymer), methyl-phenyl silicone-polyester resin (copolymer), silicone resin-alkyd resin (copolymer), modified silicone resin and mixtures thereof.

[0107] Advantageously, one or more silicone resins are selected from the group consisting of methyl silicone and / or phenyl silicone and / or methylphenyl-silicone resin, methyl silicone-polyester resin (copolymer), phenyl silicone-polyester resin (copolymer), methyl-phenyl silicone-polyester resin (copolymer), silicone-alkyd resin (copolymer), modified silicone resin and mixtures thereof.

[0108] The silicone resin can be obtained from precursors selected in particular from hydrogenated silicones, 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.

[0109] The single-layer (3) silicone resin can form a network consisting of a combination of four single organosiloxane units denoted as M, D, T, and Q, depending on the degree of substitution of silicon atoms by oxygen, as described in the table below, where R is an organic substituent as described below.

[0110]

Table 1

[0111] The organopolysiloxane material or polymer is obtained by crosslinking from a precursor that can be a monomer or a polymer, or by a method of 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 units, the crosslink density is higher. The distribution between the M, D, T, and Q units depends on the chemical structure of the precursor, in particular this M, D, T, Q distribution within the precursor.

[0112] 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, in particular methyl, or aryl, in particular phenyl, and different types of R can be present on the same macromolecule.

[0113] The organopolysiloxanes can be either linear or slightly branched (mainly D groups), or branched or highly branched (mainly T and Q groups). Linear or slightly branched organopolysiloxanes are generally 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 resins are in a substantially solid form, or, especially, in the form of a solution in a solvent or in the form of an aqueous emulsion, in liquid form, provided that they have a rather low molecular weight. They can be copolymerized with organopolysiloxanes that do not contain silicon, such as those selected in particular from polyester, acrylic, alkyd, polyurethane and epoxy resins.

[0114] When the crosslinking is by hydrolysis-condensation, it is carried out using hydroxy or alkoxy reactive functional groups present on the organopolysiloxane, in particular methoxy, ethoxy or butoxy.

[0115] When the crosslinking is by polyaddition (or hydrosilylation), it is carried out by reaction between a reactive vinyl functional group (-CH=CH2) present in one of the organopolysiloxanes and a reactive silyl-hydride functional group (Si-H) present on another organopolysiloxane mixed with the first one.

[0116] All 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 far as the molecular structure allows. Silicone oils containing at least one reactive functional group are called "reactive oils". The reactive functional groups can be at the ends (terminals) of the macromolecular chains or distributed along the chains.

[0117] The silicone-polyester resin has, in particular, a silicone / polyester mass ratio of, for example, 90 / 10, 80 / 20, 70 / 30, 60 / 40, 50 / 50, 40 / 50, 30 / 70, 20 / 80, 10 / 90, and is preferably from 80 / 20 to 50 / 50.

[0118] The linear PDMS silicone oils are either pure or pre-emulsified in water and are characterized by their molecular weight, which is mainly a direct increasing function of the viscosity of the pure oil. They are then characterized by the presence or absence of reactive functional groups, such as hydroxyl (silanol) on the silicon atom, their number, and their position on the molecular chain. For example, reactive oils having a viscosity of 50 to 20,000 mPa·s, particularly 300 to 5000 mPa·s, can be used, which have at least one reactive functional group, preferably at least two reactive functional groups, which can be located at the ends of the chain.

[0119] Examples of polymer precursors that react by polyaddition include polymethylhydrosiloxane, vinylmethylsiloxane, vinyl-terminated, particularly linear, polydimethylsiloxane (PDMS), vinyl-terminated diphenylsiloxane-dimethylsiloxane copolymer, hydride-terminated polydimethylsiloxane, hydride-terminated polyphenylmethylsiloxane, cyclic vinylmethylsiloxane, vinyl-MQ resin, trimethylsilyl-terminated polymethylhydrosiloxane, trimethylsiloxane-terminated copolymer of methylhydrosiloxane and dimethylsiloxane, MQ resin hydride, etc., and combinations thereof.

[0120] The polymeric precursors that react by hydrolysis-condensation can be silicone resins or silicone oils, such as, 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 copolymer of diphenylsiloxane-dimethylsiloxane, poly(2-acetoxyethylsilsesquioxane), organically modified alkoxysilanes and their oligomers, and all similar macromolecules thereof, and mixtures thereof can be mentioned.

[0121] The organopolysiloxane material or polymer can also be obtained by crosslinking one or more monomer precursors and mixtures of one or more polymer precursors as described above, and one or more oligomer precursors which can be linear, branched or cyclic. These oligomer precursors have a lower molecular weight than the polymer precursors. In order to promote the high crosslink density of the finally obtained organopolysiloxane polymer, polymers and / or oligomer precursors containing several reactive functional groups above 2, preferably far above 2, can be added to the mixture as "cocondensers".

[0122] Whether copolymerized with an organic polymer or not, the monomer and / or polymer precursor, especially the silicone resin, serves as a polymer binder to obtain a solid organopolysiloxane polymer combined with the thermoplastic resin of each layer.

[0123] The silicone oil type organopolysiloxane precursor can be regarded as an additive when added in a small amount (generally 0.1 - 5% dry) to the overall formulation of the layer, independently of the other components for the formation of the solid organopolysiloxane polymer.

[0124] Catalysts may be required for crosslinking. - In the case of crosslinking of organopolysiloxanes by hydrolysis - polycondensation, the formulation may contain metal catalysts such as platinum, tin, zinc, zirconium and cerium - based metal complexes, in particular platinum - cyclovinylmethyl - siloxane complexes, tin octoate, zinc octoate, zirconium octoate, cerium octoate and tin dibutyl laurate. - When crosslinking organopolysiloxanes by hydrosilylation, the addition of a catalyst may be required. This may be, for example, platinum or a suitable platinum - based catalyst such as the Karstedt catalyst or the Ashbys catalyst.

[0125] A crosslinking agent, for example, a crosslinking agent having an Si - H bond may be present.

[0126] According to one embodiment, the proportion of the silicone resin in the layer (3b) is 20% by weight or more based on the total weight of the layer (3b) respectively.

[0127] According to other embodiments, the proportion of the silicone resin in the layer (3b) is 40% by weight or more based on the total weight of the layer (3b) respectively.

[0128] According to one embodiment, the proportion of the silicone resin in the layer (3b) is 50% by weight or more based on the total weight of the layer (3b) respectively.

[0129] According to one embodiment, the proportion of the silicone resin in the layer (3c) is 20% by weight or more based on the total weight of the layer (3c) respectively.

[0130] According to other embodiments, the proportion of the silicone resin in the layer (3c) is 30% by weight or more based on the total weight of the layer (3c) respectively.

[0131] According to still other embodiments, the proportion of the silicone resin in the layer (3c) is 40% by weight or more based on the total weight of the layer (3c) respectively.

[0132] According to yet another embodiment, the proportion of the silicone resin in the layer (3c) is 50% by weight or more with respect to the total weight of the layer (3c), respectively.

[0133] According to yet another embodiment, the proportion of the silicone resin in the layer (3c) is 60% by weight or more with respect to the total weight of the layer (3c), respectively.

[0134] According to one embodiment, the proportion of the silicone resin in one or more layers (3ab) is 20% by weight or more with respect to the total weight of the layer (3ab), respectively. According to another embodiment, the proportion of the silicone resin in one or more layers (3ab) is 40% by weight or more with respect to the total weight of the layer (3ab), respectively. According to still another embodiment, the proportion of the silicone resin in one or more layers (3ab) is 50% by weight or more with respect to the total weight of each layer (3ab).

[0135] Thermoplastic polymer Advantageously, the one or more thermoplastic polymers are selected from the group consisting of polyethersulfone (PES), polyphenylene ether sulfone (PPSU), polyamideimide (PAI), polyimide (PI), poly(phenylene oxide) (PPO), poly(arylene sulfide) (PAS), polyetherimide (PEI), polybenzimidazole (PBI), liquid crystal polymer (LCP), polyphenylene sulfide (PPS), 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.

[0136] Heterocyclic thermoplastic polymer Examples of the heterocyclic thermoplastic polymer according to the present invention include polyetherimide (PEI), polyimide (PI), polyamideimide (PAI), and polybenzimidazole (PBI), or mixtures thereof.

[0137] PAEK Advantageously, one or more polyaryl ether ketones (PAEKs) are 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 PEEK.

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

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

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

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

[0142] 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 preferably greater than the proportion of the thermoplastic polymer in layer (3b).

[0143] 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).

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

[0145] The filler can not only provide color to the coating but also contribute to it.

[0146] The presence of a filler having excellent thermal conductivity can compensate for the low thermal conductivity of the PAEK polymer.

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

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

[0149] Advantageously, the metal is a transition metal and is at least one of the elements selected from B, Ni, Ti, Zr, or Hf.

[0150] Even more preferably, the one or more fillers are selected from the group consisting of the following. - Reinforcing filler: Hard organic or inorganic filler. The hard inorganic filler is preferably silicon carbide or alumina or zirconia, or graphite, or ceramic, or carbonate, or hydrated alumina, aluminum hydroxide, or particles of one or more metal oxides, graphite, graphene. - Other reinforcing fillers selected from metal oxides: Silica, mica, laminar fillers, montmorillonite, sepiolite, diopside, clays such as kaolinite and laponite, zinc oxide, quartz, and zirconium phosphate, alumina, zirconia, zinc oxide, copper oxide, and iron oxide. - Fillers selected from reinforcing fibers: Glass, 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, Zr, or Hf. For example, cubic boron nitride, diamond particles, metal particles. - Lamellar fillers that can provide lubricating properties, such as clay, graphene or graphite.

[0151] Preferred fillers in combination with organopolysiloxanes are - Reinforcing fillers: silica or carbonate with a filler content of at least 10 - 15 wt% and a maximum of 60 wt%, - Alumina, hydrated alumina, aluminum hydroxide, - silica with d50 < 0.1 μm and BET specific surface area > 30 m 2 / g, preferably 30 - 500 m 2 / g (precipitated or pyrolytic method), - 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.

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

[0153] Advantageously, the fillers present in the auxiliary layer (3a) are hard inorganic fillers, preferably particles of silicon carbide or alumina or zirconia or graphite, or carbon black, or ceramic, or particles of one or more metal oxides.

[0154] Certain inorganic hard fillers such as silicon carbide also have the advantage of being conductive fillers in addition to their mechanical reinforcement performance, and thus provide excellent thermal conductivity. The addition of this type of filler can improve cooking results by better heat diffusion from the metal substrate to the food in contact with the coating.

[0155] Advantageously, the average diameter d50 of the filler is 0.1 to 50 μm, more advantageously 5 to 15 μm.

[0156] Advantageously, the proportion of the filler in the layer is 0.5 to 30% by dry weight, preferably 5 to 20% with respect to the total weight of the layer after curing.

[0157] Advantageously, the proportion of the filler in the layer (3a) is more than 20% by weight, preferably more than 30% by weight with respect to the total weight of the layer.

[0158] Advantageously, the proportion of the filler in the layer (3c) is less than 10% by weight with respect to the total weight of the layer.

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

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

[0161] Additive Advantageously, the additive is selected from the group consisting of an antifoaming agent, a dispersant, a wetting agent, a thickener, a pH adjuster, and a reactive silicone oil.

[0162] The one or more antifoaming agents are preferably selected from the group consisting of mineral oil, diol, hydrocarbon, glyceride, oxirane, and emulsified fatty acid.

[0163] The one or more surfactants are preferably selected from the group consisting of glycol ether, ethoxylated alcohol excluding alkylphenol ethoxylate (APE), and gemini surfactant.

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

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

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

[0167] Advantageously, the proportion of the additive in layer (3a) is less than 1% by weight based on the total weight of said layer.

[0168] Advantageously, the proportion of the additive in layer (3c) is less than 20% by weight based on the total weight of said layer.

[0169] Advantageously, the proportion of the additive in one or more layers (3ab) is less than 20% by weight based on the total weight of said layer.

[0170] Colorant Advantageously, one or more colorants are selected from the group consisting of thermochromic pigments, thermostable pigments, flakes, preferably holographic flakes, and mixtures thereof.

[0171] Advantageously, the proportion of the colorant in layers (3b) and (3c) is 0.5 - 50% by dry weight based on the total weight of said layer after curing.

[0172] Advantageously, the proportion of the colorant in layer (3b) is in the range of 10% - 40% by weight based on the total weight of said layer.

[0173] Advantageously, the proportion of the colorant in layer (3c), if present, is less than 10% by weight based on the total weight of said layer.

[0174] Advantageously, the proportion of the colorant in layers (3b) and (3c) may be the same or different.

[0175] Advantageously, the nature of the colorant in layers (3b) and (3c) may be the same or different.

[0176] Thermochromic pigment Preferably, one or more thermochromic pigments are 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, where -x is equal to 0 or x is 0.001 to 0.999, -y is equal to 0 or y is 0.001 to 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.

[0177] It can be seen that A and M are different from each other in the following cases. -A is an alkali metal and can be selected from Li, Na, K, Rb, Cs. -M is an alkali metal and can be selected from Li, Na, K, Rb, Cs. -A is an alkaline earth metal and can be selected from Be, Mg, Ca, Sr, Ba. -M is an alkaline earth metal and can be selected from Be, Mg, Ca, Sr, Ba. -A is a transition metal and can be selected from Sc, TiCr, Mn, Fe, Co, Ni, Cu, Y, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Ta, W, Ir. -M is a transition metal and can be selected from Sc, TiCr, Mn, Fe, Co, Ni, Cu, Y, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Ta, W, Ir. -A is a poor metal and can be selected from Al, Zn, Ga, In, Sn. -M is a poor metal and can be selected from Al, Zn, Ga, In, Sn. -A is a semimetal and can be selected from B, Si, Ge, Sb. -M is a semimetal and can be selected from B, Si, Ge, Sb. -A is a lanthanide and can be selected from La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu. -M is a lanthanide and can be selected from La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu.

[0178] Preferably, A and M are different from each other and are B and / or Mg.

[0179] Preferably, the pigment (Bi 1-x A x )(V 1-y M y )O4 has a monoclinic scheelite crystal form at ambient temperature.

[0180] Preferably, x and y are 0, that is, the pigment (Bi 1-x A x )(V 1-y M y )O4 is bismuth vanadate (BiVO4). Advantageously, BiVO4 having a monoclinic scheelite structure at ambient temperature is used.

[0181] Bismuth vanadate is a yellow inorganic compound of the formula BiVO4 and is widely used because of its coloring properties and its lack of toxicity. It is registered in the Color Index International as Q.I. Pigment Yellow 184 and is sold in particular by Heubach (Vanadur®), BASF (Sicopal®), Ferro (Lysopac), or successively by Bruchsaler Farbenfabrik (Brufasol®).

[0182] Thermostable pigment Preferably, the one or more heat-stable pigments are selected from the group consisting of - Titanium rutile yellow pigments, - Yellow pigments derived from bismuth, for example, stabilized bismuth vanadate (Py 184 ) selected from - Red pigments, for example, perylene red (for example, PR149, PR178, and PR224), iron oxide selected from - Bismuth oxyhalide orange pigments (PO 85 ), - Bismuth vanadate orange pigments (PO 86 ), - Tin titanium zinc orange pigments (PO 82 ), - Cerium sulfide orange pigments (PO 75 , PO 78 ), - Chromium antimony titanium rutile orange-yellow pigments (PBr 24 ), - Zinc tin rutile orange-yellow pigments (Py 216 ), - Zinc tin sulfide niobium oxide orange-yellow pigments (Py 227 ), - Niobium tin double oxide orange-yellow pigments - Co3(PO4)2 - LiCoPO4 -CoAl2O4 -Cr2O3 -TiO2 -Black pigment PBk28 (copper chromite black spinel) -And mixtures thereof.

[0183] Decoration According to one embodiment, one or more layers (3b) are continuous and cover the entire layer (3a) (see Figure 1).

[0184] According to another embodiment, one or more layers (3b) do not cover the entire layer (3a) and form at least one decoration (see Figure 2).

[0185] Advantageously, one or more layers (3b) form a plurality of decorations, where one (i) contains one or more thermochromic pigments and the other (j) contains at least one reference temperature pigment composition (see Figure 3).

[0186] 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).

[0187] 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).

[0188] 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).

[0189] 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.

[0190] Advantageously, one or more flakes are particles selected from the group consisting of mica, aluminum, mica particles coated with titanium dioxide, or mixtures thereof.

[0191] Holographic flake Advantageously, one or more flakes are holographic flakes, i.e., a mixture of magnetisable and non-magnetisable particles.

[0192] The magnetisable particles may advantageously be particles containing at least one ferromagnetic metal. These magnetisable particles may be uniform, i.e., formed of the same material or composite material, i.e., these magnetisable particles have a core-shell structure in which the ferromagnetic metal is located within the core and / or shell of the particle. Examples of composite magnetisable particles include, in particular, mica flakes coated with iron oxide Fe2O3 or stainless steel fibers coated with a sol-gel material as protection against corrosion during the coating process, or flakes made of a plastic material and coated with iron oxide Fe2O3, or flakes having a core made of a ferromagnetic metal and a shell formed of a plastic material or a sol-gel material.

[0193] According to one embodiment, some of the magnetisable particles are oriented to form a three-dimensional decoration.

[0194] Advantageously, the mixture of magnetizable particles and non-magnetizable particles is present in an amount of 1 wt% to 5 wt%, preferably 2 wt% to 3 wt%, based on the weight of the layer.

[0195] Advantageously, the proportion of non-magnetizable particles in the mixture of magnetizable particles and non-magnetizable particles is 15 wt% to 40 wt% relative to the total weight of the mixture of magnetizable particles and non-magnetizable particles.

[0196] Advantageously, the magnetizable particles have a size D50 of 23 μm or less.

[0197] In the context of the present invention, the term "D50" shall mean the maximum size indicated by 50% of the particles by number.

[0198] Advantageously, the non-magnetizable particles have a size D90 that is 20% to 250% of the size D90 of the magnetizable particles.

[0199] In the context of the present invention, the term "D90" shall mean the maximum size indicated by 90% of the particles by number.

[0200] Advantageously, the magnetizable particles and / or the non-magnetizable particles are colored on the surface.

[0201] Advantageously, the non-magnetizable particles are formed of mica, aluminum, or mica coated with titanium dioxide.

[0202] Advantageously, the magnetizable particles are formed of iron, iron oxide, aluminum coated with iron, or mica coated with iron, where the iron is in the ferrite form.

[0203] Preferred embodiments 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 at least the following layers in this order, starting from the metal substrate (2). (3a) A porous hard auxiliary layer comprising one or more polyether aryl ketones (PEEK) and their mixtures, optionally a filler, optionally an additive of less than 3% by weight based on the weight of the hard auxiliary layer, and optionally a colorant(s) of less than 3% by weight based on the weight of the hard auxiliary layer. (3b) Optionally, one or more decorations containing one or more colorants. (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.

[0204] Typically, the average thickness of the hard auxiliary layer (3a) is 20 - 50 μm. This average is, for example, the average of at least 10 measurements, preferably 15 measurements, of the thickness at 10 points and 15 points respectively at random positions.

[0205] Preferably, the colorant of the one or more intermediate layers (3b) comprises pigments and / or flakes, advantageously holographic flakes.

[0206] Alternatively, the one or more intermediate layers (3b) consist of the following. · One or more colorants, especially pigments and / or flakes, advantageously holographic flakes, · One or more thermoplastic polymers preferably selected from polyamide imide (PAI), polyimide (PI), polyether imide (PEI), polybenzimidazole (PBI), polyether sulfone (PES), polyphenylene ether sulfone (PPSU), polyaryl ether ketone (PAEK), and their mixtures, · 0 - 10% filler, · 0 - 20% additive, · Optionally one or more silicone resins.

[0207] According to another alternative, the one or more intermediate layers (3b) consist of the following. · One or more colorants, in particular pigments and / or flakes, preferably holographic flakes, · 0 to 10% filler, · 0 to 20% additives, · One or more silicone resins, and · Optionally, one or more thermoplastic polymers preferably selected from polyamide-imide (PAI), polyimide (PI), polyether-imide (PEI), polybenzimidazole (PBI), polyether sulfone (PES), polyphenylene ether sulfone (PPSU), polyaryl ether ketone (PAEK), and mixtures thereof.

[0208] According to a particular alternative, the one or more intermediate layers (3b) do not contain a silicone resin.

[0209] According to another particular alternative, the one or more intermediate layers (3b) consist of the following. · One or more colorants, in particular pigments and / or flakes, preferably holographic flakes, · One or more thermoplastic polymers preferably selected from polyamide-imide (PAI), polyimide (PI), polyether-imide (PEI), polybenzimidazole (PBI), polyether sulfone (PES), polyphenylene ether sulfone (PPSU), polyaryl ether ketone (PAEK), and mixtures thereof, · 0 to 10% filler, · 0 to 20% additives, · One or more silicone resins.

[0210] According to a particular embodiment, the coating comprises two intermediate layers (3b), at least one of which is a decorative layer. Preferably, one or more of the layers (3b) form a plurality of decorations, one (i) of which contains one or more thermochromic pigments and the other (j) of which contains at least one reference temperature pigment composition.

[0211] Advantageously, the thickness of the layer (3b) is from 1 μm to 100 μm, preferably from 2 μm to 30 μm, particularly preferably from 3 μm to 10 μm.

[0212] Preferably, one or more intermediate layers (3b) cover only a part of the base layer (3a).

[0213] Alternatively, according to another embodiment, the coating does not have an intermediate layer (3b).

[0214] According to one embodiment, the finishing layer (3c) consists of one or more silicone resins and optionally one or more thermoplastic polymers.

[0215] According to another embodiment, the finishing layer (3c) consists of one or more silicone resins and one or more thermoplastic polymers.

[0216] Advantageously, the thickness of the layer (3c) is from 0.05 μm to 100 μm, preferably from 0.08 μm to 20 μm, particularly preferably from 0.1 μm to 10 μm. In a particular embodiment, the average thickness of the hard auxiliary layer (3a) is from 20 to 50 μm, the thickness of the layer (3b) is from 3 μm to 10 μm, and the thickness of the layer (3c) is between 0.1 μm and 10 μm. The average thickness of the hard auxiliary layer (3a) is, for example, the average of at least 10 measurements, preferably 15 measurements, of the thickness at random positions, such as 10 and 15 respectively.

[0217] Method The method also relates to a method for manufacturing the coated cooking element (1) according to the invention, comprising the following successive steps: a) Supplying a metal support (2) having two opposite faces; b) Optionally, treating the face (2a) of the support (2) to obtain a treated face (2a) that promotes the adhesion of the hard auxiliary layer (3a) onto the support (2). c) By means of a thermal spray onto the inner surface (2a), there is produced on the inner surface (2a) an adhesive hard auxiliary layer (3a) of a powder or dispersion of one or more polyether aryl ketones (PEAK) and their mixtures, optionally a filler, optionally an additive of less than 3% by weight relative to the weight of the hard auxiliary layer (3a), and optionally a colorant(s) of less than 3% by weight relative to the weight of the hard auxiliary layer (3a). d) Optionally, a step of drying and / or curing. e) Optionally, a step of applying one or more layers (3ab) and / or one or more intermediate layers (3b). f) A step of applying a finish layer (3c). g) A step of drying and / or curing. It includes.

[0218] Advantageously, the steps of the method according to the invention make it possible to coat a metal support (2) with a coating (3) formed by the layer (3a), optionally the layers (3ab) and (3b), and (3c).

[0219] Generally, the layers (3ab), (3b) and (3c) are wet during application. In the context of the present invention, a "wet layer" shall mean that the layer contains all or part of its solvent.

[0220] Preferably, all or part of the solvent of the wet layer is removed naturally or by a physical treatment, such as heat drying, air drying, or vacuum treatment.

[0221] Advantageously, the coating composition according to the invention can also contain at least one solvent. Advantageously, the solvent can be a protic solvent. Advantageously, the solvent can be non-toxic.

[0222] The solvent that can be used in the coating composition according to the present invention can advantageously contain at least one alcohol, and preferably can be selected from isopropanol, methanol, ethanol, and mixtures thereof.

[0223] The application of the coating is carried out in several layers. In this case, the deposition of at least one layer of the coating (3) according to the present invention on at least one of the two opposite surfaces of the support is repeated several times. Preferably, a drying step is carried out between the application of each layer, and then the curing of the coated support is carried out after the application of the last layer. The application of the coating (3) according to the method of the present invention to the support (2) makes it possible to obtain a layer of thermally stable coating.

[0224] The coating formulation to be coated 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.

[0225] Advantageously, the method for manufacturing the coated cooking element (1) according to the present invention includes one or more drying steps at 80 to 150 °C after the application of each layer. Drying can be carried out by convection or infrared rays.

[0226] The application of the coating according to the present invention can be carried out by the method according to the present invention on a shaped support or even on a locally flat area of a shaped support. A layer of thermally stable coating is obtained.

[0227] Advantageously, the manufacturing method of the coated cooking element (1) according to the present invention includes a step of shaping the metal support (2) before step c. Shaping is also called stamping.

[0228] If the shaping step precedes the application iii of the coating, the coating is preferably carried out by spraying.

[0229] If this shaping step follows the application vii of the coating, the coating is preferably produced by screen printing or by means of rollers.

[0230] The method according to the invention comprises a step g of curing / drying the element obtained in step f of the method. In the context of the present invention, "curing the coated substrate" shall mean a heat treatment that not only enables the densification of one or more coating layers applied to the substrate, but also enables the crosslinking of the organopolysiloxane (silicone resin) precursor.

[0231] In step g, curing is carried out. Generally, the curing temperature in step g is between 230 °C and 420 °C.

[0232] Advantageously, the method for manufacturing the coated cooking element (1) according to the invention comprises a single final curing step g for all the coating layers. This single curing step is carried out simultaneously for all the coating layers.

[0233] Thermal spraying, as its name indicates, consists of spraying a powder or a dispersion onto the surface.

[0234] Preferably, in step a), the metal support (2) is in the form of a disk.

[0235] Advantageously, the method according to the invention does not include a curing step other than the curing step of step g).

[0236] Preferably, the thermal spraying is a spray using a flame ("flame spray") or a low-temperature gas dynamics spray ("cold spray").

[0237] In the case of flame spraying, the spraying of the powder fraction associated with at least a partial melting of the non-fluorinated polymer material explains the discontinuities of the hard auxiliary layer (3a).

[0238] Preferably, the material intended to be sprayed is a powder material having a volume-based particle size distribution D50 of 5 μm to 60 μm, preferably 10 μm to 35 μm. Preferably, in the case of flame spraying, prior to step c) of manufacturing the hard auxiliary layer (3a), there is a step of preheating the support (2) at a low temperature. This preheating is carried out at a maximum temperature of 100°C.

[0239] Preferably, in the case of low-temperature spraying, prior to step c) of manufacturing the hard auxiliary layer (3a), there is a step of preheating the support (2) to 150 to 300°C.

[0240] Preferably, the curing step (g) is carried out in a furnace at a temperature of 230°C to 420°C.

[0241] The coating step (f) and the step (e) of applying one or more layers (3ab) can be carried out by electrostatic powder coating, solvent-phase or water-phase spraying, screen printing, roller or digital printing.

[0242] The step (e) of applying one or more intermediate layers (3b) can be carried out by pad printing, screen printing, or inkjet printing in flexography.

[0243] Article The present invention also relates to a cooking utensil (100) including a coated cooking element (1).

[0244] According to one embodiment, the cooking utensil (100) includes 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.

[0245] Advantageously, the cooking utensil (100) according to the present invention is selected from the group consisting of a saucepan, a frying pan, a pan or pot for fondue or raclette, a stew pot, a wok, a sauté pan, a crepe maker, a grill, a plancha grill, a cooking pot, a casserole, a container for a cooker or a bread-making machine, and a cooking mold.

[0246] The present invention also relates to an electric cooking appliance (200) comprising a coated cooking element (1) according to the invention and a heat source (210) designed to heat said coated cooking element (1).

[0247] Advantageously, the electric cooking appliance (200) is selected from the group consisting of an electric crepe maker, an electric raclette appliance, an electric fondue appliance, an electric grill, an electric panini grill, an electric cooking appliance, a bread maker, an electric pressure cooking appliance, a waffle maker, a rice cooker and a jam maker.

[0248] The cooking article according to the invention may in particular be a cooking article in which one of the two opposite faces of the substrate is an inner face, optionally concave, intended to be placed on the side of the food that is likely to be introduced onto or into said article, and the other face of the substrate is an outer face, optionally convex, intended to be placed facing the heat source.

[0249] By way of non-limiting example, cooking articles according to the invention include in particular cooking articles such as pans and pots, Chinese woks and sauté pans, stew pots and casseroles, crepe makers, baking pans and trays, barbecue plates and grills, and cooking bowls.

Examples

[0250] Examples and Results The objects, aspects, and advantages of the present invention will be better understood by reading the following description of specific embodiments of the present invention presented as non-limiting examples.

[0251] Of course, the present invention is in no way limited to the illustrative and diagrammatic embodiments given by way of example. Without departing from the scope of protection of the present invention, changes are possible, in particular from the point of view of the configuration of the various elements or by substitution of technical equivalents.

[0252] Raw material The raw materials of layer (3a) are described in detail below.

[0253] The raw materials of the intermediate layers (3b and 3b') and the finish layer (3c) are as follows.

[0254] - Silicone resin: · RS1: Ethoxy-functionalized silicone-polyester resin (80% silicone / 20% polyester) in a solvent phase, viscosity at 25 °C is about 2000 mPas, solids content = 75% · RS2: Ethoxy-functionalized silicone-polyester resin (50% silicone / 50% polyester) in a solvent phase, viscosity at 25 °C is about 2000 mPas, solids content = 75% · RS2: Ethoxy-functionalized silicone-polyester resin (30% silicone / 70% polyester) in a solvent phase, viscosity at 25 °C is about 2000 mPas, solids content = 75% · RS4: Methylphenyl-functionalized silicone-polyester resin in a solvent phase, viscosity at 25 °C is about 2000 mPas, solids content = 75% · RS5: Ethoxy-functionalized silicone-polyester resin (50% silicone / 50% polyester) in a solvent phase, viscosity at 25 °C is about 2000 mPas, solids content = 75% · RS6: Ethoxy-functionalized methylorganopolysiloxane resin in an aqueous emulsion, viscosity at 25 °C is about 1500 mPas, solids content = 52%

[0255] - Heterocyclic polymer resin: · Polyamide-imide resin (PAI) with 29% dry extract in N-butylpyrrolidone (NBP), Torlon from SOLVAY

[0256] - Other aromatic polymer resins: · Powder polyetheretherketone (PEEK), Vicote 703 from VICTREX, powder polymer with a d50 of 25 μm · Powder polyetheretherketone (PEEK), Vicote 704 from VICTREX, powder polymer with a d50 of 10 μm · Powder PEKK resin, KEPSTAN 7002 PT from Arkema, d50 of 20 μm · Powder PEKK resin, KEPSTAN 6002 PT from Arkema, d50 of 50 μm · Powder polyethersulfone (PES) resin, micronized grade from SOLVAY, polymer powder with d50 of 40 μm

[0257] - Alcohol solvent · Dipropylene glycol butyl ether (DPNB) · 2-Methoxy-1-methylethyl acetate (MPa) · Butyl glycol acetate (BGA) · Butyl acetate

[0258] - Surfactant and defoamer · Mineral oil: Tego Foamex K7 from Evonik · Aliphatic alcohol polyglycol ether: Genapol X080 from Clariant or Tergitole TMN-100X

[0259] - Reinforcing filler: · Pyrogenic silica: Levasil CC301 · Fumed silica post-treated with dimethyldichlorosilane: AEROSIL R972

[0260] - Pigment: · Mica: Iriodin 100 or Iriodin 300 and / or Magnaparl 5000 · Cr / Fe oxide: Sicoapal black K0098FK · Carbon black: Derussol F25 or Cabot Monarch 4750 · Perylene red Paliogen red (PR178) · Iron(III) oxide: H856 brick

[0261] - Acrylic resin: · Rohagit SD 15: 30% acrylic polymer solution in the aqueous phase

[0262] - Silicone oil: · Polyether-modified polysiloxane: TEGO GLIDE 100 · Polydimethylsiloxane oil: CT 601M

[0263] - Other additives: · AMP90: Solution of 2 - amino - 2 - methyl - 1 - propanol: 90% polymer in the aqueous phase, buffer · Metolat 368: Fatty acid ester, · Dolfynox 1030: Propoxylated polyglycol ether, wetting agent · Edaplan LA451: Anionic ester in ethanol / water, wetting agent · Tego Glide 407: Methylphenylpolysiloxane, fluidizing agent.

[0264] Operating principle of Jarmill (mechanical grinding) The ball mill involves putting the sample to be ground and the so - called grinding balls into a jar and rotating the jar around its axis at a constant speed. The rotation of the jar is generally carried out using a roller machine. This sample can be ground in a dry form or dispersed in a suitable solvent (e.g., in water or alcohol). The dispersion can also contain certain adjuvants (such as dispersants or antifoaming agents).

[0265] The median diameter of the grinding balls must be adapted to the size of the particles to be ground. The finer the particles, the smaller the diameter of the balls used. The total volume of the balls, including the voids between them, is about 50 - 60% of the internal volume of the jar. Balls of different sizes are advantageously distributed according to the following weight ratios with respect to the total weight of the balls: 25% small balls, 50% medium - sized balls, and 25% large balls. The minimum dimension of the balls is 2 - 10 mm. Stabilized alumina and zirconia are commonly used as the material of the balls.

[0266] Test Test for resistance to mechanical shock (ball impact) The impact resistance of the anti - adhesion coating evaluated by the Erichsen test according to the standard ISO 6272. This includes an impact test in which a 2 kg ball is dropped from a height of 50 cm. If necessary, an aluminum or stainless - steel plate is used for the test, and one of its sides is coated with the two - layer coating according to the invention. All plates are identical to each other (in terms of thickness and alloy properties) since a constant deformation is required in all tests.

[0267] This test includes applying an impact directly to the coating deposited on the coated surface of the plate (internal stamping test), and applying an impact to the opposite side of another plate from the coated surface (external stamping test).

[0268] After the impact, a visual inspection of the coated surface of the coating is carried out.

[0269] The impact resistance of the coating is evaluated according to the following established visual scale, on the one hand, after applying an impact directly to the coating (internal stamping test), and on the other hand, to the opposite side of the coated surface (external stamping test).

[0270] - A score of 0 is given if the following is observed. For the internal stamping test: Complete peeling of the coating over the entire deformed inner surface, revealed by the appearance of a "white" area (corresponding to a part of the metal surface without coating) in the form of a disk with a diameter of approximately 25 mm at the impact location. For the external stamping test: Also, a complete peeling of the coating over most of the area of the deformed inner surface, which is revealed by the appearance of a "white" area (corresponding to the part of the metal surface without coating) at the impact location, and this area is in the form of a disk having a diameter of at least 10 mm.

[0271] - A score of 1 is assigned when the following is observed. For the internal stamping test: There is a nearly complete peeling of the coating over most of the area of the deformed inner surface at the impact location, which is revealed by the appearance of a nearly "white" area (corresponding to the part of the metal surface without coating) at the impact location, and this area is in the form of a disk having a diameter on the order of 20 mm. For the external stamping test: There is a nearly complete peeling of the coating over a medium area of the deformed inner surface, which is revealed by the appearance of a "white" area without coating at the impact location, and it is in the form of a disk having a diameter on the order of 10 mm.

[0272] - A score of 2 is assigned when the following is observed. For the internal stamping test: At the impact location, there is a nearly complete peeling of the coating over a medium area of the coated inner surface, which is revealed by the appearance of a "white" area without coating at the impact location, and it is in the form of a disk with a diameter of 10 mm. For the external stamping test: At the impact location, a white area in the form of a disk with a diameter of less than 10 mm is observed, where large chips extend over the metal surface of the support with a relatively high chip density.

[0273] - A score of 3 is assigned when the following is observed. For the internal stamping test: At the impact location, a central area enabling the metallic appearance where large chips are observed. For the external stamping test: A white surface in the form of a disk with a diameter of less than 10 mm, where fine chips extending in the metal can be observed at a moderately high density at the impact position.

[0274] - A score of 4 is assigned when the following is observed. For the internal stamping test: At the position of the collision, a region in the form of a small-diameter disk where fine chips are observed and extend in the metal at a considerably low density. For the external stamping test: There are several depressions falling into the metal, which are at the location of the collision.

[0275] - A score of 5 is assigned when the following is observed. For the internal stamping test: At the position of the collision, a slight halo that is slightly brighter than the coating is observed. For the external stamping test: There is no change in the appearance of the coating.

[0276] The higher the score obtained, the higher the impact resistance of the coating.

[0277] SEM / EDXS property evaluation SEM is a highly versatile multifunctional instrument that can acquire images of the surface structure and morphology of materials with a resolution of several nm and a very large depth of field, and also provides quality (BSE) chemical information and quantitative chemical information (EDXS, lateral resolution of about 1 μm).

[0278] EDXS is a technique that analyzes the X-rays generated by the interaction between an electron beam and a sample to provide the elemental composition of the sample. The EDXS spectrum contains peaks corresponding to the characteristic radiation of specific elements. The quantitative chemical properties of the sample are estimated from the EDXS spectrum.

[0279] The SEM-EDXS analysis technique can combine topographic surface analysis by a scanning electron microscope (SEM) with chemical analysis using energy-dispersive X-ray spectroscopy (EDXS).

[0280] The principle of the SEM is based on the detection of secondary electrons. An electron beam (referred to as primary electrons) contacts the surface of the sample. Upon collision with the atoms present on the surface, the primary electrons can transfer energy to the electrons within the outer shells of these atoms. These electrons are then emitted and are called secondary electrons. The analysis of these electrons coming from the surface layer provides information regarding topography. When the primary electrons collide with the atoms, these atoms can enter an excited state. When returning to the stable state, they emit X-rays whose wavelength is specific to the nature of the atoms. Therefore, the analysis of these X-rays provides information regarding the chemical properties of the sample.

[0281] Physicochemical analysis by SEM-EDXS analysis of the surface also shows the macroporosity of this PEEK or PEEK / SiC auxiliary layer.

[0282] Accumulation of partially melted PEEK particles results in a layer with very high porosity.

[0283] The silicone coating applied by spraying can penetrate the macropores of the auxiliary layer, and after cross-linking of the silicone resin, this generates a composite material without the need for post-treatment (such as hot pressing).

[0284] Silicone optionally inter-penetrates with the macromolecular chains of PEEK in the presence of a silicon carbide filler and forms a high-density network with excellent mechanical properties by fixing the silicone within the porous PEEK or PEEK / SiC network (Figure 5).

[0285] Porosity evaluation test by X-ray microtomography analysis X-ray microtomography is a powerful non-destructive inspection technique that can generate magnified 3D images of a sample. Its operation is based on the same physical principles as medical scanners and can achieve better spatial resolution of less than 1 micrometer. This technique consists of acquiring a large number of radiographic images of the sample from multiple angles in order to digitally reconstruct a 3D map of the phases that make up the sample.

[0286] X-ray imaging consists of passing an X-ray beam through the sample and measuring the spatial distribution of the intensity of the beam emitted from the sample on a detector.

[0287] In X-ray microtomography, especially in X-ray tubes and synchrotrons, various X-ray sources can be used. These two types of sources have different characteristics and affect the acquisition of microtomography.

[0288] In our analysis, the source used was a synchrotron, which, unlike an X-ray tube, emits a parallel beam of X-rays. The magnification of the radiographic image is performed by the detector. This incorporates an optical system that can be adjusted to select pixels of the desired size. Therefore, it is not necessary to bring the sample and the source closer to each other to improve the acquisition resolution, overcoming the limitations of the size of the object and enabling access to a pixel size of less than 1 μm.

[0289] The X-rays used in X-ray imaging have sufficient energy to pass through most materials. They are only slightly absorbed by light elements and can pass through substances of large thickness. When the X-ray beam passes through a sample, it is affected by various physical mechanisms revealed by the decrease in its intensity until it exits the sample. This attenuation is proportional to the thickness of the passing phase and the attenuation coefficient. Therefore, each unit sensor of the detector measures the intensity that depends on the path of the substance through which the beam passes. These local intensity measurements are then digitized and converted to form a grayscale image called a radiograph or radiographic projection.

[0290] The radiographic system can also produce magnification of the projected image through the shape of the beam emitted by the X-ray source or via the detection system.

[0291] Low-density regions correspond to low grayscale (nearly black), and high-density regions correspond to high grayscale (nearly white). These contrasts in grayscale enable the differentiation of phases of different densities.

[0292] The distribution of grayscale in microtomography data can be visualized on a histogram. The grayscale histogram provides information, in particular, on the volume fractions of the various phases of the sample.

[0293] Scratch resistance test (scratch test) : Using a Rockwell diamond tip with a radius of 200 μm, the coating is gradually loaded while increasing the applied force from 0 to 20 Newtons. The traces of the damage are then observed by an optical microscope. The delamination value recorded for the coating corresponds to the force at which distinct cracks are observed up to the metal in the film. The parameters of the rate of increase of the load and the movement speed of the tip are kept constant in all tests.

[0294] For each sample, five scratches are made and the average of five peel values in metal is recorded.

[0295] Example 1: Porous PEEK auxiliary layer + silicone on aluminum Procedure: - Raw materials PEEK (polyetheretherketone) is manufactured and sold under the brand name VICTREX VICOTE PEEK® 703, having a diameter D50 of 25 μm, a glass transition temperature of 143 °C, and a melting temperature of 343 °C. - Equipment: Flame spray torch, Eutectic-Castodyn DS8000 equipped with a reference frame nozzle Eutectic-Castodyn module SSMA40 - The moving speed of the torch is 150 - 200 mm / s - Dual powder feeder, Sulzer Metco, and the flow rate of the powder mixture: 2 - 7 g / min - Thickness of the auxiliary layer: 10 - 50 μm - Injection gas: Compressed air - Fuel gas: Acetylene, varying from 10 to 16 l / min, and the acetylene pressure is varied from 0.5 bar to 1 bar - Fuel gas: Oxygen is varied from 10 to 20.0 l / min, and the oxygen pressure is varied from 3 to 5 bar - Temperature of the support during the application of the hard base: Above ambient temperature (on the order of 2 - 250 °C) - Application distance from the torch to the workpiece, 10 - 20 cm - Workpiece rotation speed, 400 - 800 rpm

[0296] The thermal spraying method by flame spraying or thermal spraying using flame spraying comprises the following steps: a) Supplying a metal support in the form of a disk, including two opposite surfaces; b) Shaping the support to give a shape of a carrot including a bottom and side walls extending from the bottom, thus defining a concave inner surface and a convex outer surface suitable for receiving food. c) Optionally, in order to obtain a treatment surface that promotes the adhesion of the hard base to the support, a step of treating the inner surface of the support; d) A step of manufacturing an adhesive hard base on the inner surface of the support; e) A step of manufacturing a coating on the hard base formed in step d); characterized by including In the step d) of manufacturing the hard base, a ceramic and / or polymer material in powder form is thermally sprayed onto the inner surface to form on the inner surface of the carrot, which is at least discontinuous, and the discontinuous portions are substantially uniformly distributed on the inner surface, in the form of a partially melted and crystallized surface dispersion layer, and the step b) of shaping the support is carried out before the step d) of manufacturing the hard base or after the step e) of manufacturing the ceramic coating.

[0297] The silicone coating composed of layers (3b), (3b') and (3c) is applied onto the macroporous auxiliary layer (3a) as described below.

[0298] Finally, the composite PEEK / silicone coating is cured at 250 °C for 45 minutes.

[0299] Example 2: Porous PEEK polymer auxiliary layer containing silicon carbide and silicone on aluminum Procedure: - Raw materials PEEK (polyetheretherketone) is manufactured and sold under the brand name of VICTREX VICOTE PEEK® 703, having a D50 diameter of 25 μm, a glass transition temperature of 143 °C, and a melting temperature of 343 °C. Silicon carbide (brand name SIKA ABR I F500), D50 diameter = 12.8 μm - Equipment: Flame spray torch, Eutectic-Castodyn DS8000 equipped with a reference frame nozzle Eutectic-Castodyn module SSMA40 - The moving speed of the torch is 150 - 200 mm / s - Dual powder feeder, Sulzer Metco, and powder mixture flow rate: 2 - 7 g / min - Thickness of the auxiliary layer: 10 - 50 μm - Injection gas: Compressed air - Fuel gas: Acetylene, vary from 10 to 16 l / min, and acetylene pressure varies from 0.5 bar to 1 bar - Fuel gas: Oxygen varies from 10 to 20.0 l / min, and oxygen pressure varies from 3 to 5 bar - Temperature of the support during the application of the hard base: Above ambient temperature (on the order of 2 - 250 °C) - Coating distance from the torch to the workpiece, 10 - 20 cm - Workpiece rotation speed, 400 - 800 rpm

[0300] The ratio of PEEK / SiC is 70 / 30.

[0301] Next, a silicone coating composed of layers (3b), (3b’) and (3c) is prepared and applied in the same manner as in Example 1.

[0302] Figure 7: The average size of the equivalent diameter of the pores in the hard auxiliary layer is 14.9 μm (measured by X-ray microtomography within 43 μm from the metal surface).

[0303] Example 3: Porous PEEK polymer auxiliary layer containing silicon carbide / cold spray method The cold spray method makes it possible to obtain thick and homogeneous solid deposits on the surface of the substrate to be coated. The principle of cold spray is the high speed of powder particles that physically deform upon collision with the substrate. A stream of pressurized gas (0.1 - 5 MPa) is heated (25°C - 1000°C) and then injected into a Laval type convergent-divergent tube. In this type of tube, called a nozzle, the gas is accelerated until it reaches supersonic speed. The powder is injected into the gas stream either upstream or downstream of the nozzle. The gas stream carries the powder particles at high speed towards the substrate. If their kinetic energy is sufficient, the particles deform upon impact, like the substrate. Under deformation, the particles adhere to the substrate by means of mechanical bonding and, depending on their properties, by chemical or metallurgical bonding. Subsequent particles are deposited on top of the previously mentioned layer and thus form a more or less thick deposit. The sprayed particles remain in a solid state.

[0304] Description of the spray device: The cold spray used is a CGT kinetics 3000 combined with a PF4000 powder dispenser. The pressure range is 1 - 3 MPa and the temperature range is 300 - 500°C. The gas used is nitrogen. The spray is carried out using a tungsten carbide "MOC24" nozzle with a diameter of less than 1 mm, mounted perpendicular to the sample and held at 80 mm from the substrate. Irradiation speed of 300 mm.s-1 in a 1 mm supply step.

[0305] An aluminum carrot with a thickness of 45 / 10 is degreased and then shot-peened or sandblasted before performing a surface treatment suitable for removing organic contaminants. The roughness has an Ra on the order of 5 μm and the surface state is as described above. This disk is preheated to a maximum temperature of 260°C and used to apply a mixture of PEEK and silicon carbide powders in a 70 / 30 mass ratio by the cold spray method (dynamic spray with cold gas).

[0306] PEEK (polyetheretherketone) is manufactured and sold under the brand name of VICOTE PEEK® 703 with a volume-based diameter D50 = 25 μm.

[0307] To obtain the discontinuous deposits of the above powders and deposit them to a thickness of this layer on the order of 50 μm, a thermal method by cold spray is used.

[0308] Next, a silicone coating consisting of layers (3b), (3b') and (3c) is prepared and applied in the same manner as in Example 1.

[0309] After single curing at 250 °C for 30 minutes, the coating has a slightly rough but crack-free surface.

[0310] Step of obtaining layers (3b), (3b’) and (3c): Intermediate layer (3b) Next, a continuous layer (3b) is deposited by spraying onto one of the layers (3a) of Examples 1, 2 and 3, and this continuous layer is selected from the layer compositions described below: layer 3b1, layer 3b2 and layer 3b3:

[0311]

Table 2

[0312]

Table 3

[0313]

Table 4

[0314] The aqueous composition of layer 3b is prepared according to the ball milling method. The ball mill is carried out in a jar as described above. This sample can be ground in a dry form or dispersed in a suitable solvent (e.g., in water or alcohol, or in a solvent). The dispersion can also contain certain adjuvants (such as dispersants or defoamers).

[0315] The thickness of this layer 3b is 10 μm to 20 μm, preferably 12 μm to 15 μm.

[0316] Intermediate layer (3b’) and finish layer (3c) The substrate on which the layer (3a) and the continuous layer (3b) are coated as described above is coated with a multilayer anti-adhesion coating composed of an intermediate layer 3b' (6 - 8 μm) dried at 100°C for 4 minutes and a finish layer 3c (14 - 18 μm). The assembly is finally heated to 250°C in 30 minutes to 1 hour, i.e., the method includes only one curing step after the deposition of various layers.

[0317] The composition of the intermediate layer 3b’ is deposited by spraying and is as described below. Layers 3b’1 and 3b’2:

[0318]

Table 5

[0319]

Table 6

[0320]

Table 7

[0321] The composition of the finish layer 3c is deposited by spraying and is as described below: Layers 3c1 - 3c10:

[0322]

Table 8

[0323]

Table 9

[0324]

Table 10

[0325]

Table 11

[0326]

Table 12

[0327]

Table 13

[0328]

Table 14

[0329]

Table 15

[0330]

Table 16

[0331]

Table 17

[0332] Comparative example: Silicone without PEEK auxiliary layer on aluminum In this comparative example, a polymer auxiliary layer is not applied to the sandblasted aluminum substrate. Instead, the same silicone layer as in Examples 1 and 2 is directly applied.

[0333] The methods of formulation, coating, and final curing are also not changed with respect to Example 1.

[0334] Test results and SEM / EDXS property evaluation Mechanical shock resistance test The results are described below.

[0335]

Table 18

[0336] Characteristic evaluation method of anti-adhesion coating: Egg test performance The method for evaluating the anti-adhesion coating properties is carried out based on the egg test conforming to Paragraph 3.3.2 of the standard AFNOR NF D 21-511 and is performed as follows. The sample is washed and the water remaining on the surface is wiped off. The inner surface of the container body is dried in advance. The cooking container is heated to a temperature of 140 - 170 °C on a gas range. An egg of size 60 / 65 is cracked and then poured into the center of the hot cooking container. Then wait until the egg solidifies (6 - 9 minutes). The egg is removed from the cooking container with the help of a spatula, and the coating is washed using a wet vegetable sponge. Through this action, the anti-adhesion properties of the cooking container are evaluated.

[0337] And the record is made as follows. Score 100: The egg is completely removed using a plastic spatula. Score 75: The egg is not completely removed, but the coating can be easily washed with a wet sponge. Score 50: The egg is not completely removed, but the coating can be washed with a wet sponge. Score 25: The eggs are not completely removed, and the coating is not washed with a damp sponge. Grade 0: The eggs are not removed, and the coating cannot be washed with a damp sponge.

[0338]

Table 19

[0339] According to the comparative example, similar results are obtained in the absence of the base layer (3a).

[0340] All of the silicone-polyester resin-based coatings according to the present invention exhibit good anti-adhesion properties while adhering to the metal.

Claims

1. 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 at least the following layers in this order, starting from the metal substrate (2): (3a) A porous hard auxiliary layer consisting of one or more polyether aryl ketones (PEAK) and their mixtures, optionally a filler, optionally an additive of less than 3% by weight based on the weight of the hard auxiliary layer, and optionally a colorant of less than 3% by weight based on the weight of the hard auxiliary layer; (3b) Optional one or more intermediate layers consisting of 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 finishing layer consisting of one or more silicone resins and optionally: - One or more thermoplastic polymers, and / or - One or more fillers, and / or - One or more additives, and / or - Flakes ;

2. The coated cooking element (1) according to claim 1, characterized in that the average equivalent diameter of the pores in the hard auxiliary layer (3a) is more than 5 μm.

3. The coated cooking element (1) according to claim 2, characterized in that the average equivalent diameter of the pores in the hard auxiliary layer (3a) is more than 8 μm, preferably more than 10 μm.

4. The coated cooking element (1) according to any one of claims 1 to 3, characterized in that the median equivalent diameter of the pores in the hard auxiliary layer (3a) is more than 6 μm, preferably more than 7 μm.

5. The coated cooking element (1) according to any one of claims 1 to 4, characterized by the presence of pores in the hard auxiliary layer (3a) having an equivalent diameter of more than 30 μm, preferably at least 1% of the number of pores in the hard auxiliary layer (3a) having an equivalent diameter of more than 30 μm.

6. The coated cooking element (1) according to any one of claims 1 to 5, characterized in that the average thickness of the hard auxiliary layer (3a) is more than 5 μm, preferably more than 15 μm.

7. The coated cooking element (1) according to any one of claims 1 to 6, characterized in that the one or more polyether aryl ketones correspond to more than 50% by weight, preferably more than 70% by weight, of the hard auxiliary layer (3a).

8. The coated cooking element (1) according to claim 7, characterized in that the one or more polyether aryl ketones correspond to more than 97% by weight of the hard auxiliary layer (3a), and the remainder is optionally filled up to 100% by additives.

9. The coated cooking element (1) according to any one of claims 1 to 8, characterized in that the filler corresponds to more than 20% by weight, preferably more than 30% by weight, of the hard auxiliary layer (3a).

10. The coated cooking element (1) according to any one of claims 1 to 9, characterized in that the hard auxiliary layer (3a) has a surface roughness Ra of 5 μm to 100 μm.

11. The coated cooking element (1) according to any one of claims 1 to 10, characterized in that the polyether aryl ketone of the hard auxiliary layer (3a) is PEEK.

12. The coated cooking element (1) according to any one of claims 1 to 11, characterized in that the at least one silicone resin is selected from the group consisting of methyl silicone and / or phenyl silicone and / or methyl-phenyl-silicone resin, methyl silicone-polyester resin (copolymer), phenyl silicone-polyester resin (copolymer), methyl-phenyl-silicone-polyester resin (copolymer), silicone-alkyd resin (copolymer), modified silicone resin, and mixtures thereof.

13. The coated cooking element (1) according to any one of claims 1 to 12, characterized in that the one or more fillers are selected from the group consisting of ceramic, and / or mineral, and / or metal, and / or hydrophobic silica, and / or diamond particle filler.

14. The one or more thermoplastic polymers are selected from the group consisting of polyethersulfone (PES), polyphenylene ether sulfone (PPSU), polyamideimide (PAI), polyimide (PI), poly(phenylene oxide) (PPO), poly(arylene sulfide) (PAS), polyetherimide (PEI), polybenzimidazole (PBI), liquid crystal polymer (LCP), polyphenylene sulfide (PPS), polyaryl ether ketone (PAEK) including polyether ketone (PEK), polyether ether ketone (PEEK), polyether ketone ketone (PEKK), polyether ether ketone ketone (PEEKK), and polyether ketone ether ketone ketone (PEKEKK), and mixtures thereof, the coated cooking element (1) according to any one of claims 1 to 13.

15. The one or more colorants are selected from the group consisting of thermochromic pigments, thermostable pigments, flakes, preferably holographic flakes, and mixtures thereof, the coated cooking element (1) according to any one of claims 1 to 14.

16. The one or more thermochromic pigments are 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, wherein -x is equal to 0 or x is 0.001 to 0.999, -y is equal to 0 or y is 0.001 to 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, The coated cooking element (1) according to claim 15.

17. The one or more thermostable pigments are -titanium rutile yellow pigment, - A yellow pigment derived from bismuth (e.g., stabilized bismuth vanadate (Py １８４ ), selected from), -red pigments (e.g., selected from perylene red, iron oxide), - Bismuth oxyhalide orange pigment (PO ８５ ) - Bismuth vanadate orange pigment (PO ８６ ) - Tin titanium zinc orange pigment (PO ８２ ) - Cerium sulfide orange pigment (PO ７５ , PO ７８ ), - Chromium Antimony Titanium Orange - Yellow Pigment (PBr ２４ ) - Zinc Tin Rutile Orange - Yellow Pigment (Py ２１６ ) - Zinc sulfide - tin niobium oxide orange - yellow pigment (Py ２２７ ) -niobium tin double oxide orange-yellow pigment -Co ３ (PO ４ ) ２ -LiCoPO ４ -CoAl ２ O ４ -Cr ２ O ３ -TiO ２ -black pigment PBk28 (copper chromite black spinel) -and mixtures thereof selected from the group consisting of, the coated cooking element (1) according to claim 15 or 16.

18. The one or more holographic flakes are a mixture of magnetizable particles and non-magnetizable particles, the coated cooking element (1) according to any one of claims 15 to 17.

19. The coated cooking element (1) according to any one of claims 1 to 18, characterized in that the metal substrate (2) is a substrate made of aluminum, stainless steel, cast iron or cast aluminum, iron, titanium, or copper.

20. The coated cooking element (1) according to any one of claims 1 to 19, characterized in that the proportion of the silicone resin in the layer (3c) is 20% by weight or more based on the total weight of the layer (3c).

21. The coated cooking element (1) according to any one of claims 1 to 20, characterized in that the 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%.

22. The coated cooking element (1) according to any one of claims 1 to 21, characterized in that the proportion of the filler in the layer (3a) is more than 20% by weight, preferably more than 30% by weight, based on the total weight of the layer.

23. The coated cooking element (1) according to any one of claims 1 to 22, characterized in that the proportion of the filler in the layer (3c) is less than 10% by weight based on the total weight of the layer.

24. A method for manufacturing the coated cooking element (1) according to any one of claims 1 to 23, comprising: a) supplying a metal support (2) having two opposite surfaces; b) optionally, treating the surface (2a) of the support (2) to obtain a treated surface (2a) that promotes the adhesion of the hard auxiliary layer (3a) onto the support (2); c) generating an adhesive hard auxiliary layer (3a) on the inner surface (2a) by thermal spraying onto the inner surface (2a) a powder or dispersion of one or more polyether aryl ketones (PEAK) and their mixtures, optionally a filler, optionally an additive of less than 3% by weight based on the weight of the hard auxiliary layer (3a), and optionally a colorant(s) of less than 3% by weight based on the weight of the hard auxiliary layer (3a); d) optionally, drying and / or curing; e) optionally, applying one or more layers (3ab) and / or one or more intermediate layers (3b); f) applying the finish layer (3c); g) drying and / or curing. A manufacturing method comprising the above steps.

25. A cooking utensil (100) comprising a coated cooking element (1) according to any one of claims 1 to 23.

26. A cooking utensil (100) according to claim 25, comprising a heating surface (6) intended to be brought into contact with an external heat source, the heating surface (6) being on the opposite side of a cooking surface (5) intended to be brought into contact with food during cooking.

27. A cooking utensil (100) according to claim 25 or 26, selected from the group consisting of a saucepan, a frying pan, a fondue or raclette pan or pot, a stew pot, a wok, a sauté pan, a crepe maker, a grill, a plancha grill, a cooking pot, a casserole, a container for a cooker or bread maker, a cooking mold.

28. An electric cooking appliance (200) comprising a coated cooking element (1) and a heat source (210) configured to heat the coated cooking element (1), the coated cooking element (1) being the coated cooking element (1) according to any one of claims 1 to 23.

29. An electric cooking appliance (200) according to claim 28, selected from the group consisting of an electric crepe maker, an electric raclette appliance, an electric fondue appliance, an electric grill, an electric plancha grill, an electric cooking appliance, a bread maker, an electric pressure cooking appliance, a waffle maker, a rice cooker and a jam maker.

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