Universal varnish

Abstract

The present invention relates to the 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 thiol functions (-SH) 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 item.

Description

Title of the invention: Universal varnish

[0001] The invention applies in the field of non-stick coatings for heated household articles, in particular for kitchen articles 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.

[0002] 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.

[0003] The Applicant proposes a universal varnish for making non-stick or improving the non-stick performance 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, whatever the chemical nature of this coating, organic or mineral, and whatever the support to which the coating is applied.

[0004] This varnish has the advantage of being compatible with food contact and stable at food cooking temperatures. DEFINITIONS

[0005] 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.

[0006] 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. The first layer of the coating is a primer layer.

[0007] 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.

[0008] The term "finishing layer" or "finish" means a continuous surface layer 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, if not all finishing layers, is / are transparent to allow visibility of the underlying layers, particularly when the underlying layers are decorative layers. The finishing layer(s) protects the underlying layers from mechanical attack and gives 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.

[0009] 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, of one or more colors. A decor is clearly visible to the user with the naked eye and at a conventional distance from the household item.

[0010] "Overlapping layers" means partially or completely superimposed layers. These layers may be in the form of partially overlapping patterns, for example concentric discs.

[0011] “Adjacent layers” means non-overlapping layers. These layers may be in the form of identical or different non-overlapping patterns, preferably uniformly distributed.

[0012] The term "temperature reference pigment composition" means a composition comprising a pigment which, at a given temperature, makes it possible to indicate to the user that the optimum usage 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 usage temperature is reached when the colours are identical, or the optimum usage temperature is reached when the colours are visually very different.

[0013] The “temperature reference pigment composition” may comprise a pigment which has:

[0014] - the same color as the thermochromic pigment composition at the temperature optimal use,

[0015] * either because this pigment has the same color at room temperature as the thermochromic pigment composition at the optimum operating temperature and does not change color with temperature,

[0016] * either because this pigment has a different color at room temperature of that of the thermochromic pigment composition which evolves to the same color as the thermochromic pigment composition at the optimal use temperature,

[0017] - a color very different from that of the thermochromic pigment composition at the optimal temperature of use, whether this pigment changes color or not with the evolution of the temperature.

[0018] The optimum use 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.

[0019] The temperature reference pigment composition is thermochromic or thermostable.

[0020] The temperature reference pigment composition may be, for example, a cooking temperature reference pigment composition or an indication of the risk of overheating.

[0021] 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).

[0022] 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.

[0023] By "thermochromic pigment or pigmentary composition", it is meant, within the meaning of the present invention, a pigment or a pigmentary composition which changes color depending on the temperature in a given temperature range, this change being reversible. This change in color is visible to the user with the naked eye and at a conventional operating distance.

[0024] The term "thermostable pigment" means a pigment which does not exhibit a change in color when subjected to an increase in temperature in a given temperature range or which exhibits a change in shade when subjected to an increase in temperature in a given temperature range which is so small that it is not visible to the user with the naked eye and at a distance.

[0026] AE = of classic use.

[0025] 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: ( ) 2 + ( a / - 2 + - bfj 2

[0027] Li*, ai* and bi* characterizing the L*a*b values ​​of said compound at room temperature

[0028] L2*, a2* and b2* characterizing the L*a*b values ​​of said compound at 200°C.

[0029] By "the colors are identical" we mean indistinguishable by the user with the naked eye and at a conventional operating distance.

[0030] By the expression "cooking article", it is necessary to understand within the meaning of the present invention an object intended to cook 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.

[0031] By the expression "electric cooking appliance", it is necessary to understand within the meaning of the present invention a heating object having its own heating system such as an electric crepe maker, electric raclette appliance, electric fondue appliance, electric grill, electric griddle, electric cooker, bread machine, electric pressure cooking appliance.

[0032] The term "coating" means all the layers adhering to the metal 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.

[0033] In the present invention, the % by weight are expressed in dry weight, i.e. without solvent. 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 thiol functions (-SH)

[0037] 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.

[0038] 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 coating support.

[0039] Another object 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:

[0040] a) Provision of a support (2) having at least one face to be coated (2a),

[0041] b) Application on this at least one face to be coated (2a) of said metal support of a coating (3),

[0042] c) Application on said coating (3) of a according to the invention.

[0043] Another object 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.

[0044] Another object of the invention relates to a method of 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:

[0045] 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);

[0046] 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);

[0047] b) Application of the coating (3);

[0048] c) Application to said coating (3) of a varnish according to the invention.

[0049] Another object 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.

[0050] Surprisingly, the Applicant has developed a varnish which makes it possible to provide a slippery or non-stick character to any type of coating and which can be implemented during an in-line industrial process. This new use of a varnish based on an elastomer silicone composition results in the following qualities:

[0051] 1. facilitated implementation;

[0052] 2. very good resistance to soiling and, advantageously;

[0053] 3. good spreading of the varnish composition on a coating layer;

[0054] 4. adhesion to the coating;

[0055] 5. absence of coloring of the varnish but shine;

[0056] 6. sufficient mechanical resistance of the surface layer of varnish;

[0057] 7. easily applicable on various types of supports;

[0058] 8. and economical.

[0059] 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. FIGURES

[0060] [Fig. 1]: diagram of heating element according to the invention with layer (3b) is continuous and covers the entire layer (3a)

[0061] [Fig.2] ; diagram of heating element according to the invention with the layer (3b) does not cover the entire layer (3a) and forms a decoration

[0062] [Fig.3]: diagram of heating element according to the invention with layer (3b) consisting of two decorations (i) and (j)

[0063] [Fig.4] ; Pattern distribution diagram. 4A = adjacent non-overlapping patterns. 4B = partially overlapping patterns. 4C = overlapping patterns.

[0064] [Fig.5]: diagram of a culinary article according to the invention

[0065] [Fig.6]: diagram of an electrical cooking appliance according to the invention DETAILED DESCRIPTION

[0066] A first object of the invention concerns the use of a varnish comprising:

[0067] (a) at least one organopolysiloxane carrying reactive vinyl functions (-CH=CH2 ) And

[0068] (b) at least one other organopolysiloxane carrying reactive thiol functions (-SH)

[0069] 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.

[0070] Advantageously, the at least one organopolysiloxane carrying reactive vinyl functions (-CH=CH2) (a) and the at least one other organopolysiloxane carrying reactive thiol functions (-SH) (b) are silicone oils.

[0071] VARNISH

[0072] 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.

[0073] Advantageously, the varnish according to the invention consists of: - (a) at least one organopolysiloxane carrying reactive vinyl functions (-CH=CH2) and (b) at least one other organopolysiloxane carrying reactive thiol functions (-SH), and optionally a radical initiator, - one or more thermoplastic polymers, and / or - one or more additive(s), and / or - one or more coloring agents.

[0074] The at least one organopolysiloxane carrying reactive vinyl functions (-CH=CH2) and the at least one other organopolysiloxane carrying reactive thiol functions (-SH) are precursors which react to obtain an elastomer silicone.

[0075] 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.

[0076] [Tables 1] Structure Degree of substitution | Symbol 1 by oxygen | 1 | M £ ............................................................................................ 2 DRO ■ j 1 î —ù-yi'-o- 4 | Q ।

[0077] The precursors of the elastomer are organopolysiloxanes. 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, it being possible for different natures of R to be present on the same macromolecule.

[0078] 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.

[0079] 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 thiol functions (-SH) present on the other organopolysiloxane mixed with the first.

[0080] This crosslinking can be done by thermal activation, or chemical activation using a catalyst.

[0081] Advantageously, the organopolysiloxanes carrying reactive functions of the varnish according to the invention are silicone oils.

[0082] The 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 comprising 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.

[0083] The addition of a catalyst may be necessary for crosslinking, such as a radical initiator.

[0084] This may be a thermally activated radical initiator such as, for example, 2,2'-Azobis(2-methylpropionamidine) dihydrochloride (or V50).

[0085] It can be a radical initiator activated by UV irradiation such as for example Irgacure®651 (2,2-Dimethoxy-2-phenylacetophenone).

[0086] COATING

[0087] The coating (3) is of a nature suitable for heating elements for household articles.

[0088] A person skilled in the art will know how to choose the appropriate coating depending on the household item and its use(s).

[0089] 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), optionally one or more intermediate layer(s) and one or more finishing layer(s).

[0090] The varnish according to the invention can be the last finishing layer.

[0091] 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.

[0092] When the coating (3) comprises several layers, they may be identical or different in the nature of the components, in percentage by weight of the components, in thickness, etc.

[0093] The coating (3) may comprise:

[0094] - one or more additive(s), and / or,

[0095] - one or more coloring agent(s), and / or

[0096] - one or more charge(s).

[0097] The coating (3) may be of organic, inorganic or hybrid nature.

[0098] The coating (3) may be of a ceramic nature, for example of the sol-gel type, po polymeric, for example based on thermoplastic polymers, based on silicone resin or based on enamel.

[0099] THERMOPEASTIC POLYMERS

[0100] 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.

[0101] PAEK

[0102] Advantageously, the polyaryletherketone(s) (PAEK) is (are) chosen from the group consisting of: polyetherketones (PEK), polyetheretherketone (PEEK), poly-etherketoneketones (PEKK), polyetheretherketoneketones (PEEKK) and polyetherketo-neetherketoneketones (PEKEKK), particularly preferably is (are) PEEK.

[0103] Other aromatic thermoplastic polymers

[0104] As aromatic thermoplastic polymer(s), examples which are suitable according to the invention are poly(phenylene oxide) (PPO), poly(arylethersulfone) polymer (PAES), and in particular polyethersulfone (PES), poly-phenylene ether sulfone (PPSU), poly(arylene sulfides) (PAS) and in particular polyphenylene sulfide (PPS), liquid crystal polymers and mixtures thereof.

[0105] Heterocyclic thermoplastic polymers

[0106] As heterocyclic thermoplastic polymers, polyetherimides (PEI), polyimides (PI), polyamideimides (PAI) and polybenzymidazole (PBI), or mixtures thereof, are cited as examples suitable according to the invention.

[0107] 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.

[0108] According to one variant, the PAEK is implemented in the form of a suspension and the PAEK particles in the PAEK suspensions have a particle size with a d50 of approximately 10 pm to 15 pm.

[0109] 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 10%.

[0110] ADDITIVES

[0111] Advantageously, said additives are chosen from the group consisting of anti-foam agents, dispersing agents, wetting agents, thickeners, pH adjusters, reactive silicone oils.

[0112] Said anti-foaming agent(s) are preferably chosen from the group consisting of mineral oils, diols, hydrocarbons, glycerides, oxirane, emulsified fatty acids.

[0113] The surfactant(s) is (are) preferentially chosen from the group consisting of glycol ether, ethoxylated alcohol excluding alkyl phenol ethoxylates (APE), gemini surfactants.

[0114] The dispersing agent(s) is (are) preferentially chosen from the group consisting of anionic dispersants such as fatty acid derivatives.

[0115] Said thickeners are preferably chosen from the group consisting of acrylic-based or polyurethane-based copolymer, cellulose, pyrogenic silica.

[0116] Said pH adjusters are preferably chosen from the group consisting of Bronsted bases: ammonia, amines (triethylamine, triethanolamine, etc.), hydroxides (soda, potash, etc.), carbonates.

[0117] 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.

[0118] COLOURING AGENTS

[0119] Advantageously, the coloring agent(s) is / are chosen from the group consisting of thermochromic pigments, thermostable pigments, glitter, preferably hologram glitter, and mixtures thereof.

[0120] Advantageously, the proportion of coloring agents in the varnish according to the invention, when they are present, is less than 10% by weight relative to the total weight of said layer.

[0121] Advantageously, the varnish according to the invention is transparent. In this case, if it comprises coloring agents, these coloring agents are glitter. Thermochromic pigments

[0122] Preferably, the thermochromic pigment(s) is / are chosen from the group consisting of Bi2O3, Fe2O3, V2O5, WO3, CeO2, In2O3, Yi^CaojeTii^Vo.ieCW Agi, (Bil x A j(V| VM jO4avcc : - x is equal to 0 or x is between 0.001 and 0.999, - y is equal to 0 or y is between 0.001 and 0.999, - A and M are selected from the group consisting of nitrogen, phosphorus, an alkali metal, an alkaline earth metal, a transition metal, a poor metal, a metalloid or a lanthanide, - A and M are different from each other.

[0123] Knowing that A and M are different from each other, when:

[0124] - A is an alkali metal, it can be chosen from Li, Na, K, Rb, Cs,

[0125] - M is an alkali metal, it can be chosen from Li, Na, K, Rb, Cs,

[0126] - A is an alkaline earth metal, it can be chosen from Be, Mg, Ca, Sr, Ba,

[0127] - M is an alkaline earth metal, it can be chosen from Be, Mg, Ca, Sr, Ba,

[0128] - A 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,

[0129] - 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,

[0130] - A is a poor metal, it can be chosen from Al, Zn, Ga, In, Sn,

[0131] - M is a poor metal, it can be chosen from Al, Zn, Ga, In, Sn,

[0132] - A is a metalloid, it can be chosen from B, Si, Ge, Sb,

[0133] - M is a metalloid, it can be chosen from B, Si, Ge, Sb,

[0134] - A is a lanthanide, it can be chosen from La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu,

[0135] - M is a lanthanide, it can be chosen from La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu.

[0136] Preferably, A and M different from each other are B and / or Mg.

[0137] Preferably, the pigment (Bii_xAx)(Vi_yMy)04 has a monoclinic scheelite crystallographic form at room temperature.

[0138] Preferably, x and y are 0, i.e. the pigment (Bii_xAx)(Vi_yMy)O4 is Bismuth Vanadate (BiVO4). Advantageously, a BiVO4 with a monoclinic scheelite crystallographic structure at room temperature is used.

[0139] Bismuth Vanadate is a yellow inorganic compound with the formula BiVO4, widely used for its color properties and its 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®). Thermostable pigments

[0140] Preferably, the thermostable pigment(s) is / are chosen from the group consisting of:

[0141] - Yellow titanium rutile pigment,

[0142] - Yellow pigment derived from bismuth, for example selected from vanadates of stabilized bismuth (Py i84)

[0143] - Red pigment, for example selected from perylene red (for example PR149, PR178 and PR224), iron oxide,

[0144] - Orange pigment of bismuth oxyhalides type (PO85),

[0145] - Bismuth vanadate orange pigment (PO86)

[0146] - Zinc tin titanium orange pigment (PO82)

[0147] - Cerium sulfide orange pigment (PO75; PO78)

[0148] - Orange-yellow pigment of the antimony titanium chrome rutile type (PBr24)

[0149] - Orange-yellow pigment of tin and zinc rutile type (Py2i6)

[0150] - Niobium tin zinc sulfide orange-yellow pigment (Py227)

[0151] - Orange-yellow pigment of double oxides of tin and niobium

[0152] - Co3(PO4)2

[0153] - LiCoPO4

[0154] - CoA12O4

[0155] - Cr2O3

[0156] - TiO2

[0157] - Black pigment PBk28 (Copper chromite black spinel)

[0158] - and their mixtures. Decors

[0159] According to one embodiment, the layer(s) (3b) is(are) continuous and covers the entire layer (3a) (see [Fig.l]).

[0160] According to another embodiment, the layer(s) (3b) do(es) not cover the entirety of the layer (3a) and form(s) at least one decoration (see [Fig.2]).

[0161] Advantageously, the layer(s) (3b) 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 [Fig.3]).

[0162] 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 distributed uniformly over the entire surface and alternating with respect to each other (see Figure 4A).

[0163] 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).

[0164] 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). Sequins

[0165] The flakes that can be used in the context of the present invention can 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 that can be used in the context of the present invention can be treated to give a particular color effect.

[0166] Advantageously, the flake(s) is / are particles chosen from the group consisting of particles of mica, aluminum, mica coated with titanium dioxide or mixtures thereof. Hologram sequins

[0167] Advantageously, the glitter(s) is / are hologram glitter, i.e. a mixture of magnetizable particles and non-magnetizable particles.

[0168] 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.

[0169] According to one embodiment, a portion of said magnetizable particles is oriented so as to form a three-dimensional decoration.

[0170] 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.

[0171] 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.

[0172] Advantageously, the magnetizable particles have a dimension D50 less than or equal to 23 pm.

[0173] By the term “D50” is meant, within the meaning of the present invention, the maximum dimension presented by 50% of the particles in number.

[0174] Advantageously, the non-magnetizable particles have a dimension D90 of between 20% and 250% of the dimension D90 of the magnetizable particles.

[0175] By the term “D90” is meant, within the meaning of the present invention, the maximum dimension presented by 90% of the particles in number.

[0176] Advantageously, the magnetizable particles and / or the non-magnetizable particles are colored on the surface.

[0177] Advantageously, the non-magnetizable particles consist of mica, aluminum, or mica coated with titanium dioxide.

[0178] Advantageously, the magnetizable particles consist of iron, iron oxide, iron-coated aluminum, or iron-coated mica, the iron being in ferritic form.

[0179] CHARGES

[0180] The fillers within the meaning of the invention make it possible to provide mechanical reinforcement and can also provide hydrophobicity properties, while improving the mechanical resistance and thermal conductivity of the coating.

[0181] Fillers do not only have the function of providing color to the coating, but can contribute to it.

[0182] Advantageously, the filler(s) is / are chosen from the group consisting of ceramic fillers (SiO2, etc.) and / or mineral and / or metallic fillers (A12O3, TiO2, etc.) and / or silicas and / or diamond particles.

[0183] Preferably, the filler(s) is / are chosen from the group consisting of metal oxides, metal carbides, metal oxynitrides, metal nitrides, and mixtures thereof.

[0184] Advantageously, said metal is a transition metal, such as at least one of the elements chosen from B, Ni, Ti, Zr or Hf.

[0185] More preferably, the filler(s) is / are chosen from the group consisting of:

[0186] - fillers for reinforcement: organic or inorganic hard fillers; the fillers inorganic hard particles are preferably particles of silicon carbides or alumina or zirconia or graphite, or ceramics, or carbonate, or hydrated alumina, aluminum trihydroxide or one or more metal oxide(s), graphite, graphene;

[0187] - 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;

[0188] - fillers chosen from reinforcing fibers: glass or carbon fiber or aramid;

[0189] - conductive fillers comprising a transition metal carbide and / or a nitride of transition metal: characterized in that the transition metal is at least one of the elements chosen from B, Ni, Ti, Zr or Hf,

[0190] for example: Cubic Boron Nitride, diamond particles, metal particles;

[0191] - lamellar fillers capable of conferring lubricating properties, such as example clays, graphene or graphite.

[0192] More preferably, the filler(s) is / are chosen from the group consisting of alumina, silicon carbide, tungsten carbide, boron nitride, quartz, and mixtures thereof.

[0193] Certain inorganic hard 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.

[0194] The addition of this type of filler makes it possible to improve the culinary rendering with better diffusion of heat from the metal substrate to the food in contact with the coating.

[0195] Advantageously, the average diameter d50 of the charges is between 0.1 and 50 pm, advantageously still between 5 and 15 pm.

[0196] 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%.

[0197] SUPPORT

[0198] The support (2) is of a nature suitable for heating elements for household articles.

[0199] A person skilled in the art will know how to choose the appropriate support depending on the household item and its use(s).

[0200] For example, the support (2) is made of terracotta, glass, ceramic, pottery or a metal substrate.

[0201] 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.

[0202] For the purposes of the present invention, aluminum means a metal consisting of 100% aluminum or an aluminum alloy.

[0203] 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.

[0204] Preferably, the metal substrate comprises alternating layers of metal and / or metal alloy.

[0205] 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.

[0206] Preferably, the support (2) when it is a metal substrate is an aluminum substrate.

[0207] Advantageously, the thickness of the support (2) is between 0.5 mm and 10 mm.

[0208] Advantageously, the face (2a) of the support (2) has previously undergone a treatment of surface allowing to improve the adhesion of the coating to said substrate.

[0209] 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.

[0210] 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). The 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).

[0211] 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.

[0212] 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 an aluminum or aluminum alloy layer, anodized or not (for example intended to constitute the outer face of the article).

[0213] 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 pm.

[0214] The arithmetic mean roughness Ra is measured using a roughness meter according to ISO 4287. Ra represents the arithmetic mean of the deviations from the mean. Surface topography can be studied in particular with a profilometer with a probe equipped with a fine stylus fitted with a diamond tip, or with an optical metrology device such as Altisurf®, in which a chromatic confocal sensor allows contactless measurement. The study of this surface topography makes it possible to define the average arithmetic roughness Ra.

[0215] METHOD

[0216] The invention also relates to a varnishing method. Preferably, this method essentially consists of:

[0217] - to coat the coating of a support using the varnish composition such as defined above,

[0218] - to evaporate the solvent, and

[0219] - to crosslink the layer of varnish, possibly by thermally activating the crosslinking.

[0220] 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 / m2, preferably between 0.1 and 2.5 g / m2, even more preferably between 0.2 and 2 g / m2.

[0221] 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:

[0222] a) Provision of a support (2) having at least one face to be coated (2a),

[0223] b) Application on this at least one face to be coated (2a) of said support with a re clothing (3),

[0224] c) Application to said coating (3) of a varnish according to the invention.

[0225] 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:

[0226] 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);

[0227] 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);

[0228] b) Application of the coating (3);

[0229] c) Application to said coating (3) of a varnish according to the invention.

[0230] 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).

[0231] 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).

[0232] 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.

[0233] Optionally, the method according to the invention comprises a cooking step after step c), advantageously at a temperature between 250°C and 420°C.

[0234] Advantageously, during step b), the layer(s) of the coating (3) is / are applied by pad printing, electrostatic powdering, spray spraying, screen printing, roller application or digital printing, preferably by spraying. Advantageously, the spraying is carried out in a solvent or aqueous phase.

[0235] Advantageously, during step c), the varnish is applied by electrostatic powdering, spray spraying, screen printing, spray gun, doctor blade, coating cylinder, brush, roller application or digital printing, preferably by spraying.

[0236] Advantageously, the method according to the invention comprises a step of crosslinking c') of the varnish subsequent to or simultaneously with step c).

[0237] 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.

[0238] Advantageously, the crosslinking (c') of the varnish is carried out at a temperature of 300°C for a duration of 10 min.

[0239] Advantageously, the higher the crosslinking temperature, the shorter the crosslinking time.

[0240] 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.

[0241] According to one embodiment, the crosslinking step c') can be carried out under UV irradiation using a radical initiator activated by UV irradiation such as for example Irgacure®651 (2,2-Dimethoxy-2-phenylacetophenone).

[0242] The method may comprise an additional step d) of crosslinking the com- position applied in step c), by UV irradiation.

[0243] 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).

[0244] 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.

[0245] The thickness of the varnish applied in step c) is advantageously between 0.1 μm and 10 μm, preferably between 0.5 μm and 5 μm, even more preferably between 1 and 2 μm.

[0246] According to a variant, it is possible to provide several passes of the varnish.

[0247] The viscosity of the non-crosslinked liquid varnish as applied to the support is adjustable by dilution with solvents depending on the application processes used.

[0248] 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.

[0249] ARTICLE

[0250] 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.

[0251] According to one embodiment, this household item is a culinary item or an electrical cooking appliance and the varnish according to the invention forms a cooking face.

[0252] In this case, the varnish according to the invention is advantageously transparent.

[0253] In this case, the coloring agent of the varnish according to the invention is advantageously sequins.

[0254] 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, culinary mold, molds and plates for pastry, barbecue plates and grills, preparation bowls.

[0255] 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 face (5) intended to be placed in contact with the food during cooking.

[0256] 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 placed on the side of food likely to be introduced into or onto said article, and the other face of the substrate of which is an external face, possibly convex, intended to be placed towards a heat source.

[0257] 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.

[0258] 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).

[0259] According to one embodiment, the household item according to the invention is a small heating household appliance.

[0260] 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.

Claims

Claims

1. Use of a varnish comprising: (a) at least one organopolysiloxane carrying vinyl reactive functions (-CH=CH2) and (b) at least one other organopolysiloxane carrying thiol reactive functions (-SH) 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.

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 thiol functions (-SH) (b) are silicone oils.

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

4. Use according to claim 3, characterized in that the radical initiator is a thermally activated radical initiator such as, for example, 2,2'-Azobis(2-methylpropionamidine) dihydrochloride or a radical initiator activated by UV irradiation such as, for example, 2,2-Dimethoxy-2-phenylacetophenone.

5. 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.

6. 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 metal support a coating (3), c) Applying to said coating (3) a varnish as described in any one of claims 1 to 5.

7. Method according to claim 6 characterized in that the varnish is applied during step c) by electrostatic powdering, spray spraying, screen printing, by gun, by doctor blade, by coating cylinder, by brush, by roller application or by digital printing, preferably by spraying.

8. Method according to claim 6 or claim 7 comprising an additional step c') of crosslinking the varnish subsequent to or simultaneously with step c), preferably at a temperature of 300°C for a duration of 10 min.

9. Method according to claim 6 to 7 comprising an additional step d) of crosslinking the composition applied in step c), by UV irradiation.

10. Method according to claim 5 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 6 to 10.

12. Method of 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 as described in any one of claims 1 to 5.;

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 the cooking face.

15. Culinary article (100) according to claim 14, selected from the group consisting of a saucepan, frying pan, skillets or pots for fondue or raclette, stewpot, wok, sauté pan, crepe pan, grill, griddle, pot, casserole dish, cooker or bread machine bowl, cooking mold, molds and baking trays, barbecue plates and grills, preparation bowls.

16. An electric cooking appliance (200) according to claim 14, selected 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.

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 an article for hair care and the varnish coats one of the heating plates of said article.

Images