Universal varnish

Abstract

The invention relates to the use of a varnish comprising: (a) at least one organopolysiloxane bearing reactive vinyl functions (-CH=CH2) and (b) at least one other organopolysiloxane bearing reactive silyl hydride functions (Si-H), for rendering anti-adhesive, or improving the anti-adhesiveness of, a coating (3) applied to the surface (2a) of the support (2) of a heating element (1) for a household article.

Description

[0001] Universal varnish

[0002] The invention applies to the field of non-stick coatings for heated household items, in particular for kitchenware and electrical cooking appliances. The general field of the invention is that of polymer varnishes capable of giving supports, possibly at least partly made of polymers or ceramics, a slippery character, for easy implementation by the user.

[0003] More specifically, the invention relates to silicone compositions useful in particular for producing varnishes applicable to coatings already present on supports, in order to confer non-stick properties to this coating.

[0004] The Applicant proposes a universal varnish for making non-stick or improving the non-stick properties of a coating applied to the support of a heating element for a household item. The varnish according to the invention makes it possible to provide non-stick properties to the coating to which it is applied, regardless of the chemical nature of this coating, organic or mineral, and regardless of the support to which the coating is applied.

[0005] This varnish has the advantage of being compatible with food contact and stable at food cooking temperatures.

[0006] DEFINITIONS

[0007] The term "layer" is understood to mean, within the meaning of the present invention, a continuous or discontinuous layer. A continuous layer (or also called a monolithic layer) is a single whole forming a total flat area completely covering the surface on which it is placed. A discontinuous layer (or non-monolithic layer) may comprise several parts, thus not being a single whole.

[0008] The term "base coat", "primer coat", "bonding coat" or "bonding primer" means all the layers from the first layer applied directly to the support (it is preferable that this layer adheres well to the support and provides all its mechanical properties to the coating: hardness, scratch resistance) to the last layer before the first intermediate or decorative layer or the finishing layer if the coating does not include an intermediate layer. The first layer of the coating is a primer coat. The term "intermediate layer" means the layers inserted between the primary layer(s) and the finishing layer(s). The intermediate layer(s) may be "decorations" or "decorative layers". The intermediate layer(s) is / are not intended to be in contact with food.

[0009] The term "finish coat" or "finish" means one or more continuous surface layers applied after the intermediate layer(s) if the coating comprises one or more intermediate layer(s) or after the primary layer(s). The last layer of the coating is a finishing layer. Usually, at least the last finishing layer, or even all finishing layers, is / are transparent to allow visibility of the underlying layers, in particular when the underlying layers are decorative layers. The finishing layer(s) protect the underlying layers from mechanical attack and give the coating its non-stick properties. Preferably, in the case of a cookware or electrical cooking appliance, the last finishing layer is intended to be in contact with food.

[0010] The term "decor" or "decorative layer" means one or more continuous or discontinuous layers comprising a pigment composition. The decor may be in the form of one or more patterns, or one or more colors. A decor is clearly visible to the user with the naked eye and at a normal distance from the household item.

[0011] Overlapping layers are defined as partially or completely superimposed layers. These layers may appear in the form of partially overlapping patterns, for example, concentric discs.

[0012] "Adjacent layers" are defined as non-overlapping layers. These layers may be in the form of identical or different non-overlapping patterns, preferably uniformly distributed.

[0013] The term "temperature reference pigment composition" means a composition comprising a pigment which, at a given temperature, indicates to the user that the optimum operating temperature has been reached. This indication is made by comparing the colours of the thermochromic pigment composition and the temperature reference pigment composition. Either the optimum operating temperature is reached when the colours are identical, or the optimum operating temperature is reached when the colours are visually very different.

[0014] The “temperature reference pigment composition” may include a pigment which has:

[0015] - the same color as the thermochromic pigment composition, at the optimal operating temperature,

[0016] * either because this pigment has the same color at room temperature as the thermochromic pigment composition at the optimum temperature of use, and does not change color with temperature,

[0017] * either because this pigment has a different color at room temperature from that of the thermochromic pigment composition which evolves to the same color as the thermochromic pigment composition at the optimal temperature of use,

[0018] - a color very different from that of the thermochromic pigment composition at the optimum temperature of use, whether or not this pigment changes color with the change in temperature.

[0019] The optimum operating temperature can be achieved when the color of the temperature reference pigment composition corresponds to a color indicated in the user guide for the household article comprising the coating of the invention or to a color indicated on a color scale provided to the user with said article.

[0020] The temperature reference pigment composition is thermochromic or thermostable.

[0021] The temperature reference pigment composition may be, for example, a cooking temperature reference pigment composition or an indication of the risk of overheating.

[0022] The expression "thermochromic semiconductor" is understood to mean, within the meaning of the present invention, a mineral or organic compound which exhibits a reversible change in color upon increasing temperature. The progressive and reversible thermochromic nature of these semiconductor compounds is linked to the reduction in the width of the forbidden band of the semiconductor due to the expansion of the material. Indeed, the periodicity of the network of anions and cations leads to the gathering of energy levels into energy bands. The filled energy band with the highest energy is called the valence band and the empty energy band with the lowest energy is called the conduction band. Between these two bands, there is a forbidden band called the gap.The color of a semiconductor material can come from the presence of a charge transfer which corresponds to the passage of an electron either from a valence band to a conduction band on the same atom, or commonly from the orbital of an anion to the orbital of a cation (interatomic photonic absorption).

[0023] In the fields of application envisaged for the present invention, the optimal conditions are reached when the coating reaches a temperature suitable for cooking food, preferably between 100 and 250°C.

[0024] For the purposes of the present invention, the term "thermochromic pigment or pigment composition" means a pigment or pigment composition which changes color depending on the temperature in a given temperature range, this change being reversible. This color change is visible to the user with the naked eye and at a conventional operating distance.

[0025] The term "thermostable pigment" means a pigment which does not exhibit a change in color when subjected to an increase in temperature within a given temperature range or which exhibits a change in shade when subjected to an increase in temperature within a given temperature range so low that it is not visible to the user with the naked eye and at a conventional operating distance.

[0026] Preferably, the thermostable pigments have a color difference AE* between 25°C and 200°C of less than 10, AE* being defined by the CIE1976 formula in the CIELAB color space:

[0027] L, ai* and b characterizing the L*a*b values ​​of said compound at room temperature L?*, a?* and b?* characterizing the L*a*b values ​​of said compound at 200°C.

[0028] By "the colors are identical" we mean indistinguishable by the user with the naked eye and at a normal viewing distance.

[0029] The expression "cooking article" is understood to mean, within the meaning of the present invention, an object intended for cooking and to be heated by an external heating system such as frying pans, saucepans, sauté pans, woks, barbecue grills. A cooking article is capable of transmitting the heat energy provided by this external heating system to a material or food in contact with said object.

[0030] The expression "electric cooking appliance" is understood to mean, within the meaning of the present invention, a heating object having its own heating system, such as an electric crepe maker, an electric raclette appliance, an electric fondue appliance, an electric grill, an electric griddle, an electric cooker, a bread maker, or an electric pressure cooking appliance.

[0031] The term "coating" means all the layers adhering to the substrate and covering this substrate. The coating according to the invention obtained is advantageously solid, "solid" means the characteristic of a cohesive material insoluble in water, in usual solvents, in food components such as aqueous or fatty mixtures, even if the material may have great hardness or great flexibility such as an elastomer.

[0032] In the present invention, the % by weight are expressed in dry weight, i.e. without solvent.

[0033] SUMMARY OF THE INVENTION

[0034] A first object of the invention concerns the use of a varnish comprising:

[0035] (a) at least one organopolysiloxane carrying reactive vinyl functions (-CH=CH2) and

[0036] (b) at least one other organopolysiloxane carrying reactive silyl hydride (Si-H) functions to make non-stick or improve the non-stick of a coating (3) applied to the face (2a) of the support (2) of a heating element (1) for a household article.

[0037] Another object of the invention relates to a simple and economical method for varnishing different supports coated with a coating. The application of the varnish is carried out on the coating and not on the support of the coating.

[0038] Another subject of the invention relates to a method for obtaining a heating element (1) for a household article comprising a coated and varnished support (2) comprising the following steps: a) providing a support (2) having at least one face to be coated (2a); b) applying to this at least one face to be coated (2a) of said support a coating (3); c) applying to said coating (3) a varnish according to the invention. Another subject of the invention relates to a heating element (1) for a coated and varnished household article capable of being obtained according to the method of the invention.

[0039] Another subject of the invention relates to a method for manufacturing a household article comprising a heating element (1) for a household article comprising a coated and varnished support (2) characterized by the following steps: a) a step of providing a support (2) in the form of a substantially flat support comprising two opposite faces or a support (2) of convex or hollow shape defining a concave inner face (21) and a convex outer face (22); a') where appropriate, when a support (2) in the form of a substantially flat support is provided during step (a), a step of shaping said substrate to give it the shape of a support (2) of convex or hollow shape defining a concave inner face (21) and a convex outer face (22), said step (a') being carried out either before step (a), or before step (b) of applying the coating (3), or after step (b) and before step (c) of applying the varnish or after step (c);b) application of the coating (3); c) application to said coating (3) of a varnish according to the invention.;

[0040] Another subject of the invention relates to a household article comprising a heating element (1) coated and varnished according to the invention or capable of being obtained according to the method of the invention.

[0041] Surprisingly, the Applicant has developed a varnish which can provide a slippery or non-stick character to any type of coating and which can be implemented in an in-line industrial process. This new use of a varnish based on an elastomer silicone composition results in the following qualities:

[0042] 1. facilitated implementation;

[0043] 2. very good resistance to soiling and, advantageously

[0044] 3. good spreading of the varnish composition on a coating layer;

[0045] 4. adhesion to the coating;

[0046] 5. absence of coloring of the varnish but shine;

[0047] 6. sufficient mechanical strength of the surface layer of varnish;

[0048] 7. easily applicable on various types of supports;

[0049] 8. and economical. Advantageously, this varnish composition according to the invention has sufficient stability for use deferred from its manufacture for a storage period compatible with marketing criteria.

[0050] FIGURES

[0051] [Fig. U • diagram of heating element according to the invention with layer (3b) is continuous and covers the entire layer (3a)

[0052] [Fis.2]: diagram of heating element according to the invention with layer (3b) not covering the entire layer (3a) and forming a decoration

[0053] [Fig.3] 'heating element diagram according to the invention with layer (3b) consisting of two decorations (i) and (j)

[0054] [Fis.4] ' pattern distribution diagram. 4A = adjacent non-overlapping patterns. 4B = partially overlapping patterns. 4C = overlapping patterns.

[0055] [Fis.5] ' diagram of a culinary article according to the invention

[0056] [Fis.6]: diagram of an electrical cooking appliance according to the invention

[0057] DETAILED DESCRIPTION

[0058] A first object of the invention concerns the use of a varnish comprising:

[0059] (a) at least one organopolysiloxane carrying reactive vinyl functions (-CH=CH2) and

[0060] (b) at least one other organopolysiloxane carrying reactive silyl hydride (Si-H) functions to make non-stick or improve the non-stick of a coating applied to the support (2) of a heating element (1) for a household article.

[0061] Advantageously, the at least one organopolysiloxane carrying reactive vinyl functions (-CH=CH2) (a) and the at least one other organopolysiloxane carrying reactive silyl hydride functions (Si-H) (b) are silicone oils.

[0062] VARNISH

[0063] Advantageously, the varnish according to the invention further comprises: one or more thermoplastic polymers, and / or one or more additive(s), and / or one or more coloring agents. Advantageously, the varnish according to the invention consists of:

[0064] (a) at least one organopolysiloxane carrying reactive vinyl functions (-CH=CH2) and (b) at least one other organopolysiloxane carrying reactive silyl hydride functions (Si-H), and optionally: a metal catalyst, one or more thermoplastic polymers, and / or one or more additive(s), and / or one or more coloring agents.

[0065] The at least one organopolysiloxane carrying reactive vinyl functions (-CH=CH2) and the at least one other organopolysiloxane carrying reactive silyl hydride functions (Si-H) are precursors which react to obtain a silicone elastomer.

[0066] This silicone elastomer forms a network which can be made up of a combination of 4 simple organosiloxane units called M, D, T and Q depending on the degree of substitution by oxygen of the silicon atom, as described in the following table, where R is an organic substituent described below.

[0067] Table 1

[0068] The precursors of the elastomer are organopolysiloxanes. These macromolecules are formed of 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, different natures of R can be present on the same macromolecule. Organopolysiloxanes can be either linear or weakly branched (majority of D groups). Linear or weakly branched organopolysiloxanes are generally liquid, more or less viscous at room temperature, and are called silicone oils.

[0069] The organopolysiloxanes carrying reactive functions of the varnish according to the invention are precursors which react by a crosslinking which is a polyaddition (or hydrosilylation). This crosslinking is carried out by reaction between the reactive vinyl functions (-CH=CH2) present on one of the organopolysiloxanes and the reactive silyl hydride functions (Si-H) present on the other organopolysiloxane mixed with the first.

[0070] This crosslinking can be done by thermal activation or chemical activation. Preferably, this crosslinking is done in the presence of a catalyst.

[0071] Advantageously, the catalyst is metallic, for example platinum or a suitable platinum-based catalyst such as the Karstedt catalyst or the Ashbys catalyst.

[0072] Preferably, this reaction takes place in the presence of a metal catalyst, for example platinum or a suitable platinum-based catalyst such as the Karstedt catalyst or the Ashbys catalyst.

[0073] Advantageously, the varnish according to the invention further comprises a metal catalyst, for example platinum or a suitable platinum-based catalyst such as the Karstedt catalyst or the Ashbys catalyst.

[0074] Advantageously, the organopolysiloxanes carrying reactive functions of the varnish according to the invention are silicone oils.

[0075] Reactive functions are present on each organopolysiloxane in the number of at least one and can be present in the number of 2, 3, or more ... as much as the molecular structure allows. Silicone oils containing at least one reactive function are called "reactive oils". The reactive functions can be found either at the end of the macromolecular chain (termination), or distributed over the chain.

[0076] COATING

[0077] The coating (3) is of a nature suitable for heating elements for household items. A person skilled in the art will know how to choose the appropriate coating depending on the household item and its use(s).

[0078] Advantageously, the coating (3) comprises one or more layers. Conventionally, the coating (3) comprises in this order from the substrate (2) one or more primer layer(s) (3a), optionally one or more intermediate layer(s) (3b) and one or more finishing layer(s) (3c).

[0079] The varnish according to the invention can be the last finishing layer.

[0080] Advantageously, the coating (3) does not comprise fluorocarbon resin, also called fluorinated polymer or fluoropolymer. In other words, said coating (3) is free of fluorocarbon resin. Thus, the coating (3) does not comprise or emit perfluoroalkyl and polyfluoroalkyl compounds.

[0081] When the coating (3) comprises several layers, they may be identical or different in nature of the components, in percentage by weight of the components, in thickness, etc.

[0082] The coating (3) may comprise: one or more additive(s), and / or one or more coloring agent(s), and / or one or more filler(s).

[0083] The coating (3) may be organic, inorganic or hybrid in nature.

[0084] The coating (3) may be of a ceramic nature, for example of the sol-gel type, polymeric, for example based on thermoplastic polymers, based on silicone resin or based on enamel.

[0085] THERMOPLASTIC POLYMERS

[0086] Advantageously, the thermoplastic polymer(s) is / are chosen from the group consisting of aromatic thermoplastic polymer(s) such as polyaryletherketone(s) (PAEK), poly(arylethersulfones) (PAES), poly(arylene sulfides) (PAS) or poly(phenylene oxide) (PPO), liquid crystal polymers, heterocyclic thermoplastic polymers and mixtures thereof. PAEK

[0087] Advantageously, the polyaryletherketone(s) (PAEK) is (are) chosen from the group consisting of: polyetherketones (PEK), polyetheretherketone (PEEK), polyetherketoneketones (PEKK), polyetheretherketoneketones (PEEKK) and polyetherketoneetherketoneketones (PEKEKK), particularly preferably is (are) PEEK.

[0088] Other aromatic thermoplastic polymers

[0089] As aromatic thermoplastic polymer(s), examples suitable according to the invention are poly(phenylene oxide) (PPO), poly(arylethersulfone) polymer (PAES), and in particular polyethersulfone (PES), polyphenylene ether sulfone (PPSU), poly(arylene sulfides) (PAS) and in particular polyphenylene sulfide (PPS), liquid crystal polymers and mixtures thereof.

[0090] Heterocyclic thermoplastic polymers

[0091] Examples of heterocyclic thermoplastic polymers suitable according to the invention are polyetherimides (PEI), polyimides (PI), polyamideimides (PAI) and polybenzymidazole (PBI), or mixtures thereof.

[0092] Advantageously, the thermoplastic polymer(s) is / are chosen 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), polybenzymidazole (PBI), liquid crystal polymers (LCP), polyphenylene sulfide (PPS), polyarylether 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.

[0093] Alternatively, the PAEK is implemented as a suspension and the PAEK particles in the PAEK suspensions have a particle size with a d50 of about 10 pm to 15 pm.

[0094] Advantageously, the varnish according to the invention comprises one or more thermoplastic polymer(s), preferably in a proportion by weight of said layer of less than 15%, particularly preferably less than 10%. ADDITIVES

[0095] Advantageously, said additives are chosen from the group consisting of anti-foam agents, dispersing agents, wetting agents, thickeners, pH adjusters, reactive silicone oils.

[0096] Said anti-foaming agent(s) are preferably chosen from the group consisting of mineral oils, diols, hydrocarbons, glycerides, oxyrane, emulsified fatty acids.

[0097] The surfactant(s) is (are) preferably chosen from the group consisting of glycol ether, ethoxylated alcohol excluding alkyl phenol ethoxylates (APE), gemini surfactants.

[0098] The dispersing agent(s) is (are) preferably chosen from the group consisting of anionic dispersants such as fatty acid derivatives.

[0099] The said thickener(s) is (are) preferably chosen from the group consisting of acrylic-based or polyurethane-based copolymer, cellulose, fumed silica.

[0100] The said pH adjuster(s) is (are) preferably chosen from the group consisting of Bronsted bases: ammonia, amines (triethylamine, triethanolamine, etc.), hydroxides (soda, potash, etc.), carbonates.

[0101] Advantageously, the proportion of additives in the varnish according to the invention is less than 20% by weight relative to the total weight of said layer.

[0102] COLOURING AGENTS

[0103] Advantageously, the coloring agent(s) is / are chosen from the group consisting of thermochromic pigments, thermostable pigments, glitter, preferably hologram glitter, and mixtures thereof.

[0104] Advantageously, the proportion of coloring agents in the varnish according to the invention, when present, is less than 10% by weight relative to the total weight of said layer. Advantageously, the varnish according to the invention is transparent. In this case, if it comprises coloring agents, these coloring agents are glitter.

[0105] Thermochromic pigments

[0106] Preferably, the thermochromic pigment(s) is / are selected from the group consisting of Bi2O3, Fe2O3, V2O5, WO3, CeO2, ln2O3, Yi,84Cao,i6Tii,84Vo,i60i,84, Agi, (Bii- X HAS X ) (Vi- y My)04 with

[0107] - x is equal to 0 or x is between 0.001 and 0.999,

[0108] - y is equal to 0 or y is between 0.001 and 0.999,

[0109] - A and M are chosen from the group consisting of nitrogen, phosphorus, an alkali metal, an alkaline earth metal, a transition metal, a poor metal, a metalloid or a lanthanide,

[0110] - A and M are different from each other.

[0111] Knowing that A and M are different from each other, when:

[0112] - A is an alkali metal, it can be chosen from Li, Na, K, Rb, Cs,

[0113] - M is an alkali metal, it can be chosen from Li, Na, K, Rb, Cs,

[0114] - A is an alkaline earth metal, it can be chosen from Be, Mg, Ca, Sr, Ba,

[0115] - M is an alkaline earth metal, it can be chosen from Be, Mg, Ca, Sr, Ba,

[0116] - A is a transition metal, it can be chosen from Sc, Ti Cr, Mn, Fe, Co, Ni, Cu, Y, Zr,

[0117] Nb, Mo, Ru, Rh, Pd, Ag, Ta, W, Ir,

[0118] - M is a transition metal, it can be chosen from Sc, Ti Cr, Mn, Fe, Co, Ni, Cu, Y, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Ta, W, Ir,

[0119] - A is a poor metal, it can be chosen from Al, Zn, Ga, In, Sn,

[0120] - M is a poor metal, it can be chosen from Al, Zn, Ga, In, Sn,

[0121] - A is a metalloid, it can be chosen from B, Si, Ge, Sb,

[0122] - M is a metalloid, it can be chosen from B, Si, Ge, Sb,

[0123] - A is a lanthanide, it can be chosen from La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho,

[0124] Er, Tm, Yb, Lu,

[0125] - M is a lanthanide, it can be chosen from La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu.

[0126] Preferably, A and M different from each other are B and / or Mg.

[0127] Preferably, the pigment (Bii. x HAS x )(Vi.yMy)O4 has a monoclinic scheelite crystallographic form at room temperature. Preferably, x and y are 0, i.e., the pigment (Bii. x HAS x )(Vi. y M y )O4 is Bismuth Vanadate (B1VO4). Advantageously, a B1VO4 with a monoclinic scheelite crystallographic structure at room temperature is used.

[0128] Bismuth Vanadate is a yellow inorganic compound with the formula B1VO4, widely used for its color properties and lack of toxicity. Registered in the Colour Index International database as QI Pigment Yellow 184, it is marketed by Heubach (Vanadur®), BASF (Sicopal®), FERRO (Lysopac) and Bruchsaler Farbenfabrik (Brufasol®).

[0129] Thermostable pigments

[0130] Preferably, the thermostable pigment(s) is / are chosen from the group consisting of:

[0131] - Yellow titanium rutile type pigment,

[0132] - Yellow pigment derived from bismuth, for example selected from stabilized bismuth vanadates (Py^)

[0133] - Red pigment, for example selected from perylene red (for example PR149, PR178 and PR224), iron oxide,

[0134] - Orange pigment of bismuth oxyhalides type (POss),

[0135] - Bismuth vanadate orange pigment (POSÔ)

[0136] - Zinc tin titanium orange pigment (POs?)

[0137] - Cerium sulfide orange pigment (PO75; PO?s)

[0138] - Orange-yellow pigment of the antimony titanium chrome rutile type (PBr?4)

[0139] - Orange-yellow pigment of the rutile type of tin and zinc (Pyz-iô)

[0140] - Orange-yellow pigment of niobium oxide tin zinc sulfide (Py???)

[0141] - Orange-yellow pigment of double oxides of tin and niobium

[0142] - Co3(P04)?

[0143] - L1C0PO4

[0144] - CoAl?Û4

[0145] - Cr?O3

[0146] - TiO?

[0147] - Black pigment PBk28 (Copper chromite black spinel)

[0148] - and their mixtures. Decorations

[0149] According to one embodiment, the layer(s) (3b) is (are) continuous and covers the entire layer (3a) (see Figure 1).

[0150] According to another embodiment, the layer(s) (3b) do(es) not cover the entire layer (3a) and form(s) at least one decoration (see Figure 2).

[0151] Advantageously, the layer(s) (3 b) compose several decorations, one (i) comprising one or more thermochromic pigment(s) and the other (j) comprising at least one temperature reference pigment composition (see Figure 3).

[0152] According to one embodiment, each of the two decorations (i) and (j) is presented in the form of adjacent non-overlapping patterns. For example, each decoration is represented by different geometric patterns distributed uniformly over the entire surface and alternating with respect to each other (see Figure 4A).

[0153] According to another embodiment, the two decorations (i) and (j) are partially overlapping. For example, each decoration is represented by different geometric patterns distributed uniformly over the entire surface and partially overlapping (see Figure 4B).

[0154] Preferably, the two decorations (i) and (j) are overlapping, either because one of the two decorations is a continuous layer and the other decoration covers it in the form of patterns, or because the two decorations (i) and (j) are in the form of overlapping patterns (see Figure 4C).

[0155] Sequins

[0156] The flakes usable in the context of the present invention may be independently chosen from mica flakes, coated or not, silica flakes, coated or not, aluminum flakes, coated or not, iron oxide flakes, coated or not. Mica or silica flakes coated with titanium dioxide. The flakes usable in the context of the present invention may be treated to give a particular color effect.

[0157] Advantageously, the glitter(s) is / are particles chosen from the group consisting of particles of mica, aluminum, mica coated with titanium dioxide or mixtures thereof. Hologram glitter

[0158] Advantageously, the glitter(s) is / are hologram glitter, i.e. a mixture of magnetizable particles and non-magnetizable particles.

[0159] The magnetizable particles may advantageously be particles comprising at least one ferromagnetic metal. These magnetizable particles may be of a homogeneous nature, i.e. made of the same material, or of a composite nature, i.e. these magnetizable particles have a core-shell structure, in which the ferromagnetic metal is found in the core and / or in the shell of said particles. Examples of composite magnetizable particles include mica flakes coated with iron oxide Fe2O3 or stainless steel fibers coated with a sol-gel material, as protection against corrosion during the steps of implementing the coating, or else plastic flakes coated with iron oxide Fe2O3, or flakes whose core is made of ferromagnetic metal and the shell is formed of a plastic material or a sol-gel material.

[0160] According to one embodiment, a portion of said magnetizable particles is oriented so as to form a three-dimensional decoration.

[0161] Advantageously, the mixture of magnetizable particles and non-magnetizable particles represents between 1% and 5% by weight of the weight of the layer, preferably between 2% and 3% by weight.

[0162] Advantageously, the percentage of non-magnetizable particles in the mixture of magnetizable particles and non-magnetizable particles is between 15% and 40% by weight relative to the total weight of the mixture of magnetizable particles and non-magnetizable particles.

[0163] Advantageously, the magnetizable particles have a dimension D50 less than or equal to 23 pm.

[0164] The term “D50” means, within the meaning of the present invention, the maximum dimension presented by 50% of the particles by number.

[0165] Advantageously, the non-magnetizable particles have a dimension D90 of between 20% and 250% of the dimension D90 of the magnetizable particles. The term "D90" is understood to mean, within the meaning of the present invention, the maximum dimension that 90% of the particles have in number.

[0166] Advantageously, the magnetizable particles and / or the non-magnetizable particles are colored on the surface.

[0167] Advantageously, the non-magnetizable particles are made of mica, aluminum, or mica coated with titanium dioxide.

[0168] Advantageously, the magnetizable particles consist of iron, iron oxide, iron-coated aluminum, or iron-coated mica, the iron being in ferritic form.

[0169] CHARGES

[0170] The fillers within the meaning of the invention provide mechanical reinforcement and can also provide hydrophobic properties, while improving the mechanical resistance and thermal conductivity of the coating.

[0171] Fillers are not only intended to add color to the coating, but can also contribute to it.

[0172] Advantageously, the filler(s) is / are chosen from the group consisting of ceramic fillers (SiO?, etc.) and / or mineral and / or metallic fillers (AI2O3, TiO?, etc.) and / or silicas and / or diamond particles.

[0173] Preferably, the filler(s) is / are chosen from the group consisting of metal oxides, metal carbides, metal oxynitrides, metal nitrides, and mixtures thereof.

[0174] Advantageously, said metal is a transition metal, such as at least one of the elements chosen from B, Ni, Ti, Zr or Hf.

[0175] More preferably, the charge(s) is / are chosen from the group consisting of:

[0176] - fillers for reinforcement: organic or inorganic hard fillers; the inorganic hard fillers are preferably particles of silicon carbide or alumina or zirconia or graphite, or ceramics, or carbonate, or hydrated alumina, aluminum trihydroxide or one or more metal oxide(s), graphite, graphene;

[0177] - other fillers for reinforcement chosen from metal oxides: silica, micas, lamellar fillers, clays such as montmorillonite, sepiolite, gypsite, kaolinite and laponite, zinc dioxide, quartz, and zirconium phosphate, alumina, zirconia, zinc oxide, copper oxide, iron oxide;

[0178] - fillers chosen from reinforcing fibers: glass fiber, carbon fiber, or aramid fiber;

[0179] - conductive fillers comprising a transition metal carbide and / or a transition metal nitride: characterized in that the transition metal is at least one of the elements chosen from B, Ni, Ti, Zr or Hf, for example: cubic boron nitride, diamond particles, metallic particles;

[0180] - lamellar fillers that can provide lubricating properties, such as clays, graphene or graphite.

[0181] More preferably, the filler(s) is / are chosen from the group consisting of alumina, silicon carbide, tungsten carbide, boron nitride, quartz, and mixtures thereof.

[0182] Some hard inorganic fillers such as silicon carbide, in addition to their mechanical reinforcement performance, also have the advantage of being conductive fillers and therefore provide excellent thermal conductivity.

[0183] The addition of this type of filler improves the culinary rendering with better diffusion of heat from the metal substrate to the food in contact with the coating.

[0184] Advantageously, the average diameter d50 of the charges is between 0.1 and 50 pm, advantageously still between 5 and 15 pm.

[0185] Advantageously, the proportion of fillers in a layer of the coating (3), when it comprises them, is between 0.5 and 30% by dry weight relative to the total weight of said layer after cooking, preferably between 5 and 20%.

[0186] SUPPORT

[0187] The support (2) is of a nature suitable for heating elements for household items. A person skilled in the art will know how to choose the appropriate support depending on the household item and its use(s).

[0188] For example, the support (2) is made of terracotta, glass, ceramic, pottery or a metal substrate.

[0189] When the support (2) is a metal substrate, it is advantageously a substrate made of aluminum, stainless steel, cast iron or aluminum, iron, titanium or copper.

[0190] For the purposes of the present invention, aluminum means a metal consisting of 100% aluminum or an aluminum alloy.

[0191] Advantageously, the support (2) when it is a metal substrate is an aluminum substrate, a stainless steel substrate or a multi-layer metal substrate. The metal substrate (2) can be a two-layer or three-layer substrate, these multi-layers being able to be obtained for example by co-lamination, by hot diffusion under load (solid state bonding) or by hot or cold impact bonding.

[0192] Preferably, the metal substrate comprises alternating layers of metal and / or metal alloy.

[0193] According to one embodiment, the support (2) when it is a metal substrate is a substrate made of aluminum alloy, stainless steel or a multi-layer metal substrate whose face (2a) is made of aluminum alloy or stainless steel.

[0194] Preferably, the support (2) when it is a metal substrate is an aluminum substrate.

[0195] Advantageously, the thickness of the support (2) is between 0.5 mm and 10 mm.

[0196] Advantageously, the face (2a) of the support (2) has previously undergone a surface treatment making it possible to improve the adhesion of the coating to said substrate.

[0197] According to one embodiment, the support (2) when it is a metal substrate has undergone a surface treatment, said surface treatment being a chemical attack, brushing, hydration, sandblasting, shot blasting, a physicochemical treatment of the plasma or corona or laser type, a chemical activation or a combination of these different techniques.

[0198] Advantageously, the face of the substrate (2a) on which the coating (3) according to the invention will be applied can be treated so as to increase its specific surface area; for an aluminum substrate, this treatment can be done by anodization (creation of a tubular alumina structure), by chemical attack, by sandblasting, by brushing, by shot blasting or by adding material by means of a technology such as thermal projection (flame, plasma or arc spray). Other metal substrates can also be polished, sandblasted, brushed, micro-blasted or receive an addition of material by means of a technology such as thermal projection (flame, plasma or arc spray).

[0199] As metallic substrates which can be used in the present invention, mention may advantageously be made of anodized or non-anodized aluminum substrates, optionally polished, brushed, sandblasted, shot-blasted or micro-blasted, anodized or non-anodized aluminum alloy substrates, optionally polished, brushed, sandblasted or micro-blasted, steel substrates, optionally polished, brushed, sandblasted, shot-blasted or micro-blasted, stainless steel substrates, optionally polished, brushed, sandblasted or micro-blasted, cast steel, aluminum or iron substrates, and copper substrates, optionally hammered or polished.

[0200] Advantageously, the support (2) when it is a metal substrate can be chosen from substrates comprising ferritic stainless steel / aluminum / austenitic stainless steel layers, substrates comprising stainless steel / aluminum / copper / aluminum / austenitic stainless steel layers, cast aluminum, aluminum or aluminum alloy caps lined with an outer stainless steel base, metal co-laminated substrates, for example two-layer co-laminated substrates comprising a stainless steel layer (for example intended to constitute the inner face of the article) and a layer of aluminum or aluminum alloy, anodized or not (for example intended to constitute the outer face of the article).

[0201] Advantageously, the average arithmetic roughness Ra of the surface of the face (2a) of the support (2) when it is a metal substrate is greater than or equal to 1 μm. The average arithmetic roughness Ra is measured using a roughness meter according to the ISO 4287 standard. Ra represents the arithmetic mean of the deviations from the mean. The surface topography can be studied in particular with a profilometer with a probe equipped with a fine stylus equipped with a diamond tip, or with an optical metrology device such as Altisurf®, in which a chromatic confocal sensor allows a contactless measurement. The study of this surface topography makes it possible to define the average arithmetic roughness Ra.

[0202] PROCESS

[0203] The invention also relates to a varnishing method. Preferably, this method essentially consists of:

[0204] - to coat the coating of a support using the varnish composition as defined above,

[0205] - to evaporate the solvent, and

[0206] - to crosslink the varnish layer, possibly by thermally activating the crosslinking.

[0207] According to an advantageous arrangement of the invention, the composition of the varnish is applied to the coated support at a deposition rate of less than or equal to 5 g / m 2 , preferably between 0.1 and 2.5 g / m 2 , even more preferably between 0.2 and 2 g / m 2 .

[0208] The invention also relates to a method for obtaining a heating element (1) for a household article comprising a coated and varnished support (2) comprising the following steps: a) Providing a support (2) having at least one face to be coated (2a) b) Applying a coating (3) to said support on this at least one face to be coated (2a) c) Applying a varnish according to the invention to said coating (3).

[0209] The invention also relates to a method for manufacturing a household article comprising a heating element (1) for a household article comprising a coated and varnished support (2) characterized by the following steps: a) a step of providing a support (2) in the form of a substantially flat support comprising two opposite faces or a support (2) of convex or hollow shape defining a concave inner face (21) and a convex outer face (22); a') where appropriate, when a support (2) in the form of a substantially flat support is provided during step (a), a step of shaping said substrate to give it the shape of a support (2) of convex or hollow shape defining a concave inner face (21) and a convex outer face (22), said step (a') being carried out either before step (a), or before step (b) of applying the coating (3), or after step (b) and before step (c) of applying the varnish or after step (c);b) Application of the coating (3); c) Application to said coating (3) of a varnish according to the invention.;

[0210] Optionally, the method according to the invention comprises a step of treating the face (2a) of the support (2), to obtain a treated face (2a) promoting the adhesion of the coating (3) to the support (2), between step a) and step b).

[0211] Optionally, the method according to the invention comprises a drying step between 50°C and 150°C after application of each of the layers of the coating (3).

[0212] Optionally, the method according to the invention comprises a cooking step between step b) and step c), advantageously at a temperature between 250°C and 420°C.

[0213] Optionally, the method according to the invention comprises a cooking step after step c), advantageously at a temperature between 250°C and 420°C.

[0214] Advantageously, during step b), the layer(s) of the coating (3) is / are applied by pad printing, electrostatic powdering, spraying, screen printing, roller application or digital printing, preferably by spraying. Advantageously, the spraying is carried out in solvent or aqueous phase.

[0215] Advantageously, during step c), the varnish is applied by electrostatic powdering, spraying, screen printing, spray gun, doctor blade, coating cylinder, brush, roller application or digital printing, preferably by spraying.

[0216] Advantageously, the method according to the invention comprises a step of crosslinking c') of the varnish subsequent to or simultaneously with step c).

[0217] According to a variant, the crosslinking of the liquid silicone varnish composition applied to the coated support can generally be activated by heat treatment, at a temperature between 50 and 400°C, preferably between 50 and 300°C, obviously taking into account the maximum resistance of the support to heat.

[0218] Advantageously, the crosslinking (c') of the varnish is carried out at a temperature of 300°C for a period of 10 min.

[0219] Advantageously, the higher the crosslinking temperature, the shorter the crosslinking time.

[0220] According to one embodiment, the crosslinking step c') does not require heat treatment, in particular because the support is hot at the time of application of the varnish.

[0221] The varnish after its application according to the invention leads after spreading and hardening (drying / crosslinking) to a thin, protective, hard, smooth, shiny and transparent surface layer of varnish on a surface, preferably a surface coated with an organic or mineral polymer (e.g. ceramic).

[0222] For the purposes of the invention, the layer of varnish has, for example, a substantially homogeneous thickness less than or equal to 10 μm, preferably less than 5 μm.

[0223] The thickness of the varnish applied in step c) is advantageously between 0.1 pm and 10 pm, preferably between 0.5 pm and 5 pm, even more preferably between 1 and 2 pm.

[0224] According to a variant, it is possible to plan several coats of varnish.

[0225] The viscosity of the non-crosslinked liquid varnish as applied to the substrate is adjustable by dilution with solvents depending on the application processes used.

[0226] Said liquid varnish may comprise a solvent, preferably an aliphatic solvent. Advantageously, the aliphatic solvent is chosen from the group consisting of aliphatic hydrocarbons, linear or cyclic, whose carbon number is between 5 and 10, and mixtures thereof.

[0227] The varnish may thus comprise a solvent present at a content greater than or equal to 40%, preferably greater than or equal to 50%, particularly preferably greater than or equal to 60% by weight relative to the weight of the liquid varnish composition. Surprisingly, a varnish comprising a very high solvent content makes it possible to obtain varnish films which, after crosslinking, have a very thin thickness while being homogeneous and which are capable of making non-stick or improving the non-stick of a coating (3) applied to the face (2a) of the support (2) of a heating element (1) for a household article.

[0228] Particularly advantageously, the solvent content of the varnish is greater than or equal to 70% or 80% by weight relative to the weight of the liquid varnish composition.

[0229] Particularly advantageously, the solvent content of the varnish ranges from 70% to 90% or from 80% to 90% by weight relative to the weight of the liquid varnish composition.

[0230] For reasons of preservation, the varnish composition is advantageously presented in the form of at least a two-component system, the mixture of which is capable of crosslinking rapidly when hot by polyaddition. The ingredients are then distributed in the different parts according to the rules of the person skilled in the art; in particular the catalyst, if present, is separated from the component which comprises the organopolysiloxanes.

[0231] ARTICLE

[0232] The invention also relates to a household article comprising a heating element (1) coated and varnished according to the invention or capable of being obtained according to the method of the invention.

[0233] According to one embodiment, this household item is a cooking item or an electrical cooking appliance and the varnish according to the invention forms a cooking surface (5).

[0234] In this case, the varnish according to the invention is advantageously transparent.

[0235] In this case, the coloring agent of the varnish according to the invention is advantageously glitter.

[0236] Advantageously, the culinary article (100) according to the invention is chosen from the group consisting of saucepan, frying pan, skillets or caquelons for fondue or raclette, stewpot, wok, sauté pan, crepe maker, grill, griddle, pot, casserole dish, cooker or bread machine bowl, cooking mold, molds and plates for pastry, barbecue plates and grills, preparation bowls. According to one embodiment, the culinary article (100) comprises a heating face (6) intended to be placed in contact with an external heating source, the heating face (6) being opposite the cooking surface (5) intended to be placed in contact with the food during cooking.

[0237] According to embodiments, the layer (3c) is intended to be placed in contact with a heating source.

[0238] The culinary article according to the present invention may in particular be a culinary article of which one of the two opposite faces of the substrate is an inner face, possibly concave, intended to be arranged on the side of food likely to be introduced into or onto said article, and of which the other face of the substrate is an outer face, possibly convex, intended to be arranged towards a heat source.

[0239] Advantageously, the electric cooking appliance (200) is chosen from the group consisting of electric crepe maker, electric raclette appliance, electric fondue appliance, electric grill, electric griddle, electric cooker, bread maker, electric pressure cooking appliance, waffle makers, rice cookers and jam makers.

[0240] The electrical cooking appliance (200) comprises a coated cooking element (1) according to the invention and a heating source (210) configured to heat said coated cooking element (1).

[0241] According to one embodiment, the household item according to the invention is a small heating household appliance.

[0242] It may be an iron and the coated heating element is the soleplate of the iron or a hair care article and the coated heating element is one of the heating plates of said article.

[0243] EXAMPLES

[0244] The aims, aspects and advantages of the present invention will be better understood from the description given below of a particular embodiment of the invention presented by way of non-limiting example. Of course, the invention is in no way limited to the embodiment described and illustrated which has been given only by way of example. Modifications remain possible, in particular from the point of view of the constitution of the various elements or by substitution of technical equivalents, without departing from the scope of protection of the invention.

[0245] Examples of making culinary articles

[0246] The coating is carried out flat on aluminum discs, by screen printing or by spraying.

[0247] The coating is carried out as follows:

[0248] - each layer (3a), where applicable (3b), is coated by screen printing;

[0249] - the varnish layer (3c) is spray-coated.

[0250] After applying the layer (3c), the assembly is placed in an oven at 300°C for 30 to 45 minutes in order to dry and then crosslink the layer (3c), then the discs are left to cool.

[0251] 1. Examples and counter-example of coating (3) with a layer (3a) and, where appropriate, a layer (3b) based on PEAK as well as a layer of varnish (3c)

[0252] Raw materials

[0253] Aromatic Polymers PolyArylEtherKetone

[0254] Aqueous dispersion of PEEK (Poly ether ether ketone) supplied by the company VICTREX under the name VICOTE Coatings F804 “Vicote F804”: particle size d50 = 10 pm; dry extract between 35.5 and 39%; pH between 9.6 and 11.9; viscosity of approximately 11 sec DIN Cup n°6.

[0255] Aromatic thermoplastic polymers

[0256] PolyEtherSulfone (PES) powder resin, micronized grade VERADEL 3100 UFP from SOLVAY, polymer powder with a d50 < 40 pm.

[0257] Heterocyclic thermoplastic polymers

[0258] Polyamide imide (PAI) powder resin: TORLON AI10LS from Solvay, powder containing 90% dry extract in N-methylpyrrolidone (NMP / Water). TJ

[0259] Silicone resins

[0260] - RS1: Methyl ethoxy functionalized organopolysiloxane resin in aqueous emulsion, Viscosity at 25 °C Approx. Approx. 1500 mPas, Solids content = 52%

[0261] - PDMS_1: Polydimethylsiloxane (PDMS) resin in aqueous emulsion PDMS functionalized, Solid content 62%

[0262] Co-Solvent

[0263] - High boiling point alcohol: MPG (monopropylene glycol)

[0264] - Low boiling point alcohol: IPA (isopropanol)

[0265] Additives

[0266] - Base for adjusting the pH and solubilizing certain additives: for example AMP90 or other such as ammonia solution, triethanolamine, etc.

[0267] - Antifoam: Moussex 7114HL from Synthon

[0268] Other additives

[0269] Acrylic resin:

[0270] - Rohagit SD 15: 30% acrylic polymer solution in aqueous phase or Synthomer

[0271] - Modarez FA365 from Synthron (anionic acrylic resin), or other type and / or grade

[0272] Reinforcement charges

[0273] - Aerosil R972 (Evonik): Post-treated dimethyl dichlorosilane silica fume, specific surface area (BET) = 90 to 130 m 2 / g

[0274] - Alumina: CAHPF 240 d50 = 45-50 pm from Alteo at 100%

[0275] - Graphene: Graphen from Carbon Waters, graphene in dispersed form

[0276] - Silica: Levasil CC301, surface-modified colloidal silica in the form of an aqueous dispersion of nanoparticles with a dry extract of 30%

[0277] Pigments

[0278] - parylene red

[0279] - thermochromic pigments: bismuth oxide or commercial pigments based on mixed bismuth and vanadium oxide

[0280] - carbon black:

[0281] Sicopal® black K 0098 FK (Sun Chemical)

[0282] Derussol VDP 641: Water-based black pigment concentrate The aluminum discs are an annealed 4006 alloy, 3.4 mm thick and 340 mm in diameter. They have been brushed (roughness Ra approximately 2 pm).

[0283] In Examples 1.1 to 1.4 below, the baking of layers (3a) and (3b) before the application of the top coat (3c) is carried out in an oven between 250 and 380°C for 30 to 45 minutes, then the discs are left to cool.

[0284] Example 1.1

[0285] The coating comprises a layer (3a) obtained by screen printing coating with a thickness of 30 μm to 40 μm and a layer (3c) obtained by spray coating with a thickness of 1 to 2 μm.

[0286] Layer (3a):

[0287] The PEAK ratio is such that the PEEK resin is 100%.

[0288] Table 2 gives the composition of the wet formula for layer (3a).

[0289] Table 2

[0290] Viscosity is 12000 to 13000 cP, measured on Brookfield at 10 rpm, spindle #4.

[0291] The pH is between 9.0 and 10.5. Layer (3c):

[0292] Layer (3c) is obtained after crosslinking the following composition expressed in relative part in dry mass: an organopolysiloxane carrying reactive vinyl functions (-CH=CH2): 100 parts, another organopolysiloxane carrying reactive silyl hydride functions (Si-H): 8 parts, and a metal catalyst: 6 parts.

[0293] This dry composition above is mixed with a solvent to obtain a dry extract of the order of 10 to 20% by mass.

[0294] 1.2

[0295] The coating comprises a layer (3a) identical to the layer (3a) according to example 1.1, a layer (3c) identical to the layer (3c) according to example 1.1, as well as an intermediate layer (3b) representing a decoration deposited by pad printing in interlayers with an architecture according to figure 3.

[0296] Layer 3b (j) is a thermochromic decoration and layer 3b (i) is a thermostable decoration.

[0297] 1.3

[0298] The coating comprises: a layer (3a) identical to the layer (3a) according to example 1.1 except for its thickness of between 10 pm and 20 pm, a layer (3c) identical to the layer (3c) according to example 1.1, and an intermediate layer (3b1) whose composition is shown in the table below. The layer (3b1) is obtained by screen printing coating and has a thickness of 10 pm to 20 pm.

[0299] Layer (3b1):

[0300] The PEAK / heterocyclic polymer ratio is such that PEEK / PAI = 70 / 30 by weight.

[0301] The sum of thermoplastic polymers (PEEK + PAI) in the solid phase after curing in the coating is 76.4% by weight. The filler content (pigment + reinforcing fillers) in the cured coating is 23.1% by weight.

[0302] Table 3

[0303] Example 1.4

[0304] The coating comprises: a layer (3a) identical to the layer (3a) according to example 1.3, a layer (3c) identical to the layer (3c) according to example 1.1, and an intermediate layer (3b2) whose composition is shown in the table below. The layer (3b2) is obtained by screen printing coating and has a thickness of 10 μm to 20 μm.

[0305] Layer (3b2):

[0306] The PEAK / aromatic polymer ratio is such that PEEK / PES = 90 / 10 by weight.

[0307] The sum of thermoplastics (PEEK + PES) in solid phase after curing in the coating is 75.5% by weight.

[0308] The filler content (pigment + reinforcing fillers) in the baked coating is 24% by weight.

[0309] Table 4

[0310] PEEK dispersion: F804 68.1%

[0311] Counterexample

[0312] The coating is made in 2 identical layers by screen printing coating.

[0313] A liquid coating based on an aqueous PEEK dispersion from VICTREX, PEEK dispersion: F804, is applied by spraying. An initial sintering step at 380°C of this layer for 30 minutes is followed by cooling to room temperature.

[0314] The thickness of this first layer is between 10 pm and 20 pm.

[0315] Once the surface of this coating has cooled to room temperature, the same aqueous PEEK dispersion is spray-applied to the first layer. A second sintering step at 380°C of this layer for 30 minutes is followed by cooling to room temperature.

[0316] The coating has a very rough surface to the touch and a thickness of between 40 pm and 60 pm.

[0317] 2. Examples of coating (3) with one layer (3a) and two layers (3ba and 3bb) based on PES, as well as a layer of varnish (3c)

[0318] Raw materials:

[0319] PES Resin or PolyEtherSulfone (PES) powder resin, micronized grade from SUMITOMO, polymer powder with a d50 between 11 and 15 pm.

[0320] Solvents: o propionamide

[0321] Reinforcing fillers: o Alumina, o Silicon Carbide o Pyrogenic silica, o Colloidal silica o Colloidal alumina o Mica

[0322] Thickener: o 50% acrylic polymer solution in water o hydrogenated castor oil

[0323] Silicone resins: o Methyl-phenyl silicone resin, in flakes o Methyl silicone resin, in flakes

[0324] Solvent Alcohol o di propylene glycol butyl ether (DPNB), o MPG propylene glycol

[0325] Surfactant: o Fatty alcohol polyglycol ether

[0326] Anti-foam agent o Mineral oil

[0327] Pigments: o Mica or glitter o Carbon black:

[0328] Silicone oil: o A: non-reactive o B: reactive

[0329] Other additives: o buffering agent o anionic ester in ethanol / water, wetting agent, o aqueous dispersion of polydimethylsiloxane gum, surface tension agent

[0330] On a flat aluminum disc (30 cm in diameter), previously degreased and sandblasted to obtain a roughness of 4 to 7 pm (Ra), a continuous layer 3a is deposited, chosen from the base layer compositions (3a1 and 3a2) as described below: Layers 3a:

[0331] Layer 3a1:

[0332] Table 5

[0333] Layer 3a2:

[0334] Table 6

[0335] The thickness of this base layer 3a of the example is between 5 pm and 15 pm.

[0336] The substrate, on which the continuous base layer 3a as described above is applied, is coated with a multi-layer coating composed of a first intermediate layer 3ba (5-15|jm) which is dried at 80°C and a second intermediate layer 3bb (5-15|jm). The whole is finally heated to 300°C for about 10 min, i.e. the process comprises only one baking step, after the deposition of the different layers. 3ba layers:

[0337] The compositions of the 3ba intermediate layers deposited by screen printing are as described below (3ba1 layer and 3ba2 layer). 3ba1 layer:

[0338] Table 7

[0339] Layer 3ba2:

[0340] Table 8

[0341] The compositions of the 3bb intermediate layers deposited by screen printing are as described below (layers 3bb1 to 3bb3): Layers (3bb)

[0342] Layer 3bb1:

[0343] Table 9

[0344] Layer 3bb2:

[0345] Table 10 _

[0346] Layer 3bb3:

[0347] Table 11 Layer (3c):

[0348] Layer (3c) is identical to layer (3c) according to example 1.1.

[0349] Examples 2.1 to 2.3 correspond to the following arrangement of layers (3):

[0350] Table 12 3. Examples of coating (3) with a layer (3a) and a layer (3b) based on silicone resins, as well as a layer of varnish (3c)

[0351] A coating (example 3.1) is obtained as follows on a flat aluminum disc 3.4 mm thick and 340 mm in diameter, made of an annealed 4006 alloy and whose surface has been prepared by sandblasting.

[0352] Layer (3a):

[0353] Table 13

[0354] Layer (3b):

[0355] Table 14

[0356] Layer (3a) has a thickness of 17 μm. It is then tunnel dried up to 80°C for 5 min.

[0357] Layer (3b) has a thickness of 13 μm. It is then tunnel dried at 80°C for 5 min.

[0358] Layer (3c):

[0359] Layer (3c) is identical to layer (3c) according to example 1.1.

[0360] 4. Tests

[0361] Method for assessing drawability:

[0362] A stamping test, called the Swift test, is carried out with a Zwick BPU 400 stamping machine.

[0363] Experimental conditions: cutting of discs with a diameter of 64 mm, 33 mm punch (Limiting Drawing Ratio = 1.9), stamping die: 40 mm

[0364] The drawability of a coating on a given substrate is translated into a binary notation:

[0365] - OK: good drawability = the adhesion of the coating to the substrate after deformation by drawing is good

[0366] - Not OK: poor drawability = the adhesion of the coating to the substrate after deformation by drawing is not good.

[0367] Stamping deformation was performed in two ways; adhesion assessment is evaluated differently depending on the deformation method. These methods are estimated to give comparable results. Laboratory-scale method:

[0368] The coated aluminum substrate is deformed over a small area (a disc of approximately 10 cm in diameter is required) by a press using the "Erichsen" or "Godet" method: "Erichsen": the press deforms the surface with a conical and rounded punch to a depth of approximately 1 to 2 cm, with the coating on the outside. This deformation method also subjects the coating to stretching. If, after deformation, the coating appears very cracked or flaking / detached from the substrate, its resistance to stamping deformation is poor. To amplify the differences, a grid pattern can be made beforehand (according to ISO 2409) on the area where the punch is applied and then observed to see if many tiles have detached (with or without the application of adhesive tape).

[0369] "Godet": the press deforms the substrate with a cylindrical punch (rounded edge), with coating inside: this more closely simulates the deformation of the substrate during pan stamping, even though in the tests carried out, a 0% stretch on the skirt (the cylindrical edge) was carried out. The result is poor when we visually observe any detachment, wrinkling, ... of the coating after deformation.

[0370] Non-stick properties:

[0371] Method for evaluating non-stick coating properties: EGG PERFORMANCE TEST

[0372] The method for evaluating the properties of the non-stick coating is carried out using the egg test described in the AFNOR NF D 21-511 standard, paragraph 3.3.2, and implemented as follows:

[0373] The sample is cleaned, then any water remaining on the surface is wiped off.

[0374] The inner surface of the container body is dried and then oiled.

[0375] The oiled cooking container is heated on a gas stove to a temperature between 140 and 170°C.

[0376] Crack a 60 / 65 caliber egg and pour it into the center of the hot cooking container and wait for the egg to coagulate (6 to 9 minutes); remove the egg from the cooking container using a spatula, clean the coating using a damp vegetable sponge and evaluate the non-stick properties of the cooking container through this action, then record them:

[0377] Score of 100: the egg can be removed completely with a plastic spatula; Score of 75: the egg cannot be removed completely but the coating is easily cleaned with a damp sponge,

[0378] Score 25: The egg does not come off completely and the coating is not cleaned by a damp sponge, Score 0: The egg does not come off and the coating cannot be cleaned by a damp sponge.

[0379] Results The results of the drawability and non-stick performance tests are summarized below:

[0380] Table 15

[0381] The coatings according to the invention comprising a layer of varnish (3c) make it possible to obtain satisfactory hold (adhesion) of the coating when new and after three aging cycles in boiling water and oil, good resistance to corrosion and good anti-adhesion performance.

Claims

CLAIMS 1. Use of a varnish comprising: (a) at least one organopolysiloxane carrying reactive vinyl functions (-CH=CH2) and (b) at least one other organopolysiloxane carrying reactive silyl hydride (Si-H) functions to make non-stick or improve the non-stick nature of a coating (3) applied to the face (2a) of the support (2) of a heating element (1) for a household item.

2. Use according to claim 1, characterized in that the at least one organopolysiloxane carrying reactive vinyl functions (-CH=CH2) (a) and the at least one other organopolysiloxane carrying reactive silyl hydride functions (Si-H) (b) are silicone oils.

3. Use according to any one of the preceding claims, characterized in that the varnish comprises a catalyst.

4. Use according to claim 3 characterized in that the catalyst is platinum or a platinum-based catalyst such as the Karstedt catalyst or the Ashbys catalyst.

5. Use according to any one of the preceding claims, characterized in that the varnish further comprises: - one or more thermoplastic polymers, and / or - one or more additive(s), and / or - one or more coloring agents.

6. Use according to any one of the preceding claims, characterized in that the support is a support made of terracotta, glass, ceramic, pottery or a metal support.

7. Method for obtaining a heating element (1) for a household article comprising a coated and varnished support (2) comprising the following steps: a) providing a support (2) having at least one face to be coated (2a); b) applying to this at least one face to be coated (2a) of said support a coating (3); c) applying to said coating (3) a varnish as described in any one of claims 1 to 6.

8. Method according to claim 7 characterized in that the varnish is applied during step c) by electrostatic powdering, spraying, screen printing, spray gun, doctor blade, coating cylinder, brush, roller application or digital printing, preferably by spraying.

9. Method according to claim 7 or claim 8 comprising an additional step c') of crosslinking the composition applied in step c), preferably at a temperature of 300°C for a duration of 10 min.

10. Method according to any one of claims 7 to 9, characterized in that the thickness of the varnish applied in step c) is between 0.1 pm and 10 pm, preferably between 0.5 pm and 5 pm, even more preferably between 1 and 2 pm.

11. Heating element (1) for coated and varnished household article obtainable according to any one of claims 7 to 10.

12. Method for manufacturing a household article comprising a heating element (1) for a household article comprising a coated and varnished support (2) characterized by the following steps: a) a step of providing a support (2) in the form of a substantially flat support comprising two opposite faces or a support (2) of convex or hollow shape defining a concave inner face (21) and a convex outer face (22); a') where appropriate, when a support (2) in the form of a substantially flat support is provided during step (a), a step of shaping said substrate to give it the shape of a support (2) of convex or hollow shape defining a concave inner face (21) and a convex outer face (22), said step (a') being carried out either before step (a), or before step (b) of applying the coating (3), or after step (b) and before step (c) of applying the varnish or after step (c); b) Application of the coating (3);c) Application to said coating (3) of a varnish according to the invention as described in any one of claims 1 to 6.; 13. Household article comprising a heating element (1) coated and varnished according to claim 11 or obtainable according to claim 12.

14. Household article according to claim 13, characterized in that it is a culinary article or an electrical cooking appliance and in that the varnish forms a cooking surface (5).

15. Household article according to any one of claims 13 and 14, characterized in that it is a culinary article (100) chosen from the group consisting of saucepan, frying pan, skillets or caquelons for fondue or raclette, stewpot, wok, sauté pan, crepe pan, grill, plancha, pot, casserole dish, cooker or bread machine bowl, culinary mold, molds and plates for pastry, barbecue plates and grills, preparation bowls.

16. Household article according to any one of claims 13 and 14, characterized in that it is an electric cooking appliance (200) chosen from the group consisting of electric crepe maker, electric raclette appliance, electric fondue appliance, electric grill, electric griddle, electric cooker, bread machine, electric pressure cooking appliance, waffle makers, rice cookers and jam makers.

17. Household article according to claim 13, characterized in that it is a small heating household appliance.

18. Household article according to claim 17, characterized in that it is an iron and the varnish coats the soleplate of the iron or a hair care article and the varnish coats one of the heating plates of said article.

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