Use of a copper source in a non-stick coating

Abstract

The present invention relates to the use of a copper source in a fluoropolymer-based non-stick coating on the surface of a household article to catalyze the degradation of by-products from said coating during its manufacturing process.

Description

Title of the invention: Use of a copper source in a non-stick coating

[0001] The invention relates to the field of non-stick coatings for household articles, preferably culinary articles.

[0002] Non-stick household articles with a fluoropolymer-based coating are today made up of, among other things, a PTFE-type fluoropolymer but may also incorporate one or more adhesion resins such as PAI, PES, PAEK (polyarylether ketone), tannins, and / or organic additives such as acrylic derivatives.

[0003] The drawback of these resins and additives is that they tend to partially degrade during the sintering of PTFE and generate degradation byproducts. These byproducts, often colored, can degrade the color of the coating, particularly the top layers above the primary layers, especially if the primary layers are light-colored. This color change is visible, for example, when a light-colored decoration is applied between the primary layers and the top layer. This change manifests as a darkening or browning of the top layer.

[0004] Copper in its various forms is well known for its fungicidal and bactericidal properties (Montero et al., Antimicrob. Resist. Infect. Control, 2019, 8, 3). For example, in the form of copper sulfate, it is used in agriculture as a contact fungicide against downy mildew. In marine applications, copper-based alloys protect marine structures against the attachment of algae and marine organisms.

[0005] The interaction of various metals, including copper, with a polyimide by high-temperature contact has already been studied in the field of the microelectronics industry on flexible polymer substrates. This interaction leads to a deterioration of the electrical performance of the components due to the migration of copper within the thickness of the polyimide (Copper-Polyimide Interaction during Imidization Process of Polyamic Acid Solution to Polyimide, Electronics and Communications in Japan, Part 2, 1989, 72(7), 1516).

[0006] Surprisingly, the inventors observed that these color change phenomena at the output of the high-temperature manufacturing process can be resolved by adding a copper source to one of the coating layers. The inventors found that adding a copper source to one of the coating layers prevents the accumulation of sub- degradation products during manufacturing. The copper source therefore catalyzes the degradation of by-products from the primary layers that migrate to the upper layers. Summary of the invention

[0007] A first object of the invention relates to the use of a copper source in a fluoropolymer-based non-stick coating of the surface of a household article to catalyze the degradation of by-products from said coating during its manufacturing process.

[0008] A second object of the invention relates to a fluoropolymer-based coating for the surface of a household article comprising, in this order: - at least one primary layer comprising one or more fluoropolymer(s) and one or more bonding resin(s), the first primary layer being intended to coat a surface of the metallic substrate of said household article, - at least one layer (a) comprising at least one pigment, preferably layer (a) is a decoration;

[0009] at least one of the coating layers comprising at least one copper source.

[0010] A third object of the present invention relates to a household article comprising a substrate, preferably metallic, covered with a coating according to the invention.

[0011] A fourth object of the present invention relates to a method for preparing a fluoropolymer-based coating for the surface of a household article, comprising the following steps in this order: - application on a metallic substrate of at least one primary layer comprising one or more fluoropolymer(s) and one or more bonding resin(s), the first primary layer being intended to coat a surface of the metallic substrate of said household article, - application of at least one layer (a) comprising at least one pigment, - possibly application of at least one finishing coat,

[0012] characterized by a step of adding in at least one layer of said coating a copper source to catalyze the degradation of by-products from said coating during its manufacturing process. DEFINITIONS

[0013] The term “ambient temperature” means a temperature between 18 and 30°C.

[0014] For the purposes of the present invention, the term "layer" should be understood as a Continuous or discontinuous layer. A continuous layer (also called a monolithic layer) is a single, flat surface that completely covers the entire surface. the surface on which it is placed. A discontinuous layer (or non-monolithic layer) may comprise several parts and is therefore not a single whole.

[0015] The term "primer coat", "adhesion coat" or "adhesion primer" means all the layers whose first layer is applied directly to the support, also called substrate, (it is preferable that this layer adheres well to the support and provides all its mechanical properties to the coating: hardness, scratch resistance) contributing to the adhesion of the coating to the substrate.

[0016] The term "topcoat" or "finish" refers to a continuous and transparent surface layer, allowing perfect visibility of the underlying layers while protecting them from mechanical damage. As its name suggests, it is applied last, starting from the substrate.

[0017] The term "decoration" or "decoration layer" means one or more continuous or discontinuous layers that define at least one pattern comprising a pigment composition. The decoration may be in the form of one or more patterns, or one or more colors. A decoration is clearly visible to the user with the naked eye and at a typical viewing distance from the household item.

[0018] By copper source, we mean elemental copper and any molecule, charged or uncharged, that comprises at least one copper atom. Unless otherwise specified, the copper in copper sources is in oxidation state II.

[0019] By pigment, we mean a coloring chemical substance that is not soluble in the medium it colors. For the purposes of the present invention, pigments are not sources of copper.

[0020] The term "household article" should be understood to include cooking articles and household appliances.

[0021] The household appliances referred to herein are intended to produce heat.

[0022] The expression "culinary article" should be understood in the context of this The invention is an object intended for cooking. To do this, it is designed to receive heat treatment.

[0023] The expression "object intended to receive heat treatment" should be understood in the context of the present invention as an object which will be heated by an external heating system such as pans, pots, sauté pans, woks, barbecue grills and which is capable of transmitting the heat energy supplied by this external heating system to a material or food in contact with said object.

[0024] For the purposes of this invention, the term "object intended to produce heat" means a heating object having its own heating system, such as irons, hair straighteners, steam generators, kettles or electric cooking appliances.

[0025] The term “fluoropolymer-based coating” means a coating which comprises one or more fluoropolymer(s) in one or more of its layers.

[0026] The term "by-products from said coating during its manufacturing process" means chemical species resulting from the degradation of coating compounds, in particular from the degradation of these compounds due to heating during the manufacturing process. These chemical species are most often colored chemical species that impart an undesired color to one of the coating layers, in particular the light-colored layers.

[0027] For example, it can be recalled that PAI resins or tannins used in an ammoniacal environment partially degrade into strongly coloring amine monomers, that PES or PEEK resins partially degrade into phenolic monomers and that some additives degrade into strongly coloring acrylic monomers during the manufacturing process. DETAILED DESCRIPTION

[0028] A first object of the invention relates to the use of a copper source in a fluoropolymer-based non-stick coating of the surface of a household article to catalyze the degradation of by-products from said coating during its manufacturing process.

[0029] According to a preferred embodiment of the invention, the fluoropolymer-based non-stick coating comprises, in this order: - at least one primary layer comprising one or more fluoropolymer(s) and one or more bonding resin(s), the first primary layer being intended to coat a surface of the metallic substrate of said household article, - at least one layer (a) comprising at least one pigment

[0030] at least one of the coating layers comprising at least one copper source.

[0031] Preferably, layer (a) of the coating comprises a copper source.

[0032] Layer (a) may be a decoration. Layer (a) may also be a primary layer, preferably the last primary layer starting from the substrate.

[0033] Preferably, the copper content in layer (a) is between 0.01 and 75% relative to the total weight of said layer in the wet state, preferably between 0.05 and 30%, more preferably between 0.1 and 15%, even more preferably between 0.25 and 7.5%.

[0034] In another embodiment, the copper is present in the layer containing it in a content of between 0.01 and 75% relative to the total weight of the layer.

[0035]

[0036]

[0037]

[0038]

[0039]

[0040]

[0041]

[0042]

[0043]

[0044] the dry state, preferably between 0.05 and 30%, more preferably between 0.1 and 15%, even more preferably between 0.25 and 10%, better between 0.30 and 7.5%. In a particular embodiment, the copper source is used to prevent the color change of layer (a), it being understood that maintaining the color of layer (a) in said coating corresponds to an AE* of layer (a) less than 10.0, preferably 5.0, more preferably 3.0, between the coating according to the invention and the coating according to the invention without tack resin, AE* being defined by the CIE1976 formula in the CIELAB color space: [Math.l] Li*, ai* and bi* characterizing the L*a*b values ​​of layer (a) of the coating according to the invention without bonding resin, L2*, a2* and b2* characterizing the L*a*b values ​​of layer (a) of the coating according to the invention. In another particular embodiment, the copper source is used to prevent the color change of layer (a), it being understood that maintaining the color of layer (a) in said coating corresponds to an AE* of less than 10.0, preferably 5.0, more preferably 3.0, between layer (a) of the coating in which no layer includes a copper source and that of the coating in which one layer includes a copper source, AE* being defined by the CIE 1976 formula in the CIELAB color space: [Math.2] . 1 / _ * _ * x 2 2 f -r * -r * \ ^ AE = y[L2 ") +(¾ -¾) + {b^ - b^) Li*, ai* and bi* characterizing the L*a*b values ​​of layer (a) of the coating in which no layer includes a copper source and L2*, a2* and b2* characterizing the L*a*b values ​​of that of the coating in which one layer includes a copper source. Layer (a) may advantageously be light in color, it being understood that light color is equivalent in the CIELAB color space to values ​​of L* between 40 and 100, of a* and b* between -128 and 128, preferably values ​​of L* between 50 and 100, of a* and b* between -128 and 128, more preferably values ​​of L* between 50 and 100, of a* and b* between -80 and 80. The copper atom in the copper source can be in different oxidation states; preferably, copper is in the oxidation state IL Among the usable copper sources according to the invention are: elemental copper, organic copper salts, inorganic copper salts, and oxides. of copper. Preferably, the copper source is chosen from: organic copper salts, inorganic copper salts, copper oxides, alone or in mixtures; preferably from organic copper salts and oxides, alone or in mixtures; more preferably from copper oxide, copper acetate, or copper gluconate, alone or in mixtures. Regardless of the copper source, it may undergo chemical transformations during the manufacturing process; in particular, the copper source may oxidize or oxygenate.

[0045] Among the pigments that can be used according to the invention, the following may be mentioned: inorganic pigments whose Color Index Constitution Number (CICN) is between 77000-77999 according to the Colour Index International, Fourth Edition, Agi, Bi2O3 and a pigment of type (BiixAx)(ViyMy)04 in which:

[0046] - x is equal to 0 or x is between 0.001 and 0.999,

[0047] - y is equal to 0 or y is between 0.001 and 0.999,

[0048] - A and M are chosen from the group consisting of nitrogen, phosphorus, a metal alkaline, an alkaline earth metal, a transition metal, a post-apoct metal, a metalloid, or a lanthanide,

[0049] - A and M are different from each other.

[0050] Preferably, layer (a) comprises at least one pigment selected from the list of inorganic pigments whose Color Index Constitution Number (CICN) is between 77000 and 77999 according to the Colour Index International, Fourth Edition, Agi, Bi2O3, a pigment of type (Bii.xAx)(Vi.yMy)O4 and mixtures thereof, wherein:

[0051] - x is equal to 0 or x is between 0.001 and 0.999,

[0052] - y is equal to 0 or y is between 0.001 and 0.999,

[0053] - A and M are chosen from the group consisting of nitrogen, phosphorus, a metal alkaline, an alkaline earth metal, a transition metal, a post-apoct metal, a metalloid, or a lanthanide,

[0054] - A and M are different from each other.

[0055] In a preferred embodiment of the invention, the pigment content in layer (a) is between 0.1 and 100% by weight relative to the weight of said layer in the dry state, preferably between 0.2 and 80% by weight.

[0056] When present, (Bii_xAx)(Vi_yMy)O4 is added to one or more layer(s) of said non-stick coating.

[0057] Preferably, the concentration of (BiixAx)(ViyMy)O4 in the layer(s) to which it is added is from 0.1 to 100% by weight relative to the weight of said layer in the dry state, preferably from 0.2 to 80% by weight. (BiixAx)(ViyMy)O4 can be applied undiluted continuously or discontinuously.

[0058] During its manufacturing process, the coating may be subjected to high temperatures, for example from 150 to 450°C.

[0059] These high temperatures may be responsible for the emission of by-products from said coating penetrating into the interior of the coating.

[0060] Preferably, the compound (Bii_xAx)(Vi_yMy)04 as defined above has a monoclinic scheelite crystallographic form at room temperature.

[0061] Preferably, x and y are equal to 0, that is to say, the invention relates to the use of Bismuth Vanadate (BiVO4). Advantageously, a BiVO4 with a monoclinic scheelite crystallographic structure at room temperature is used.

[0062] Given that A and M are different from each other, when:

[0063] - A is an alkali metal; it can be chosen from Li, Na, K, Rb and Cs,

[0064] - M is an alkali metal; it can be chosen from Li, Na, K, Rb and Cs,

[0065] - A is an alkaline earth metal, it can be chosen from Be, Mg, Ca, Sr and Ba,

[0066] - M is an alkaline earth metal; it can be chosen from Be, Mg, Ca, Sr and Ba,

[0067] - 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 and Ir,

[0068] - 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 and Ir,

[0069] - A is a base metal; it can be chosen from Al, Zn, Ga, In and Sn,

[0070] - M is a base metal; it can be chosen from Al, Zn, Ga, In and Sn,

[0071] - A is a metalloid, it can be chosen from B, Si, Ge and Sb,

[0072] - M is a metalloid, it can be chosen from B, Si, Ge and Sb,

[0073] - A is a lanthanide, it can be chosen from La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu,

[0074] - M is a lanthanide, it can be chosen from La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu.

[0075] Preferably, A and M different from each other are B and / or Mg.

[0076] Advantageously, the coating according to the invention is characterized in that the AE* of the (Bii.xAx)(Vi.yMy)04 type pigment in said coating is greater than or equal to 11 between ambient temperature and 150°C, AE* being defined by the CIE1976 formula of the CIELAB color space:

[0077] [Math.3] AE =J[E2 ~) + (¾ -) + 1^2 --^ij

[0078] Li*, ai* and bi* characterizing the L*a*b* values ​​of said compound at room temperature,

[0079] L2*, a2* and b2* characterizing the L*a*b* values ​​of said compound at 150°C.

[0080] Preferably, the pigment of type (Bii_xAx)(Vi_yMy)O4> has an AE* in said coating between ambient temperature and 150°C greater than or equal to 13, particularly preferably greater than or equal to 15.

[0081] Advantageously, the coating according to the invention is characterized in that the AE* of the pigment of type (Bii.xAx)(Vi.yMy)O4, in said coating is greater than or equal to 15 between ambient temperature and 200°C, AE* being defined by the CIE1976 formula of the CIELAB color space:

[0082] [Math.4] ae* = y XZ 1 / XZ 1 / IZ J- /

[0083] Li*, ai* and bi* characterizing the L*a*b* values ​​of said compound at room temperature, L2*, a2* and b2* characterizing the L*a*b* values ​​of said compound at 200°C.

[0084] Preferably, the pigment of type (Bii.xAx)(Vi.yMy)O4, has an AE* in said coating between ambient temperature and 200°C greater than 17, particularly preferably greater than or equal to 20.

[0085] Advantageously, the evolution of the color difference AE* as a function of temperature is linear. Preferably, this linear evolution has a slope of 0.05 to 0.1, preferably greater than or equal to 0.1.

[0086] Color can be measured and characterized by means of a color classification. This classification is only possible if colors are defined by numbers, and it is through colorimetric spaces that this conversion can be achieved.

[0087] “A color space is a three-dimensional mathematical model representing the set of colors perceptible, usable or reproducible by a human or a device.” Many spaces exist with their own distribution of colors having precise coordinates (examples: the RGB space widely used by television systems or the CIELAB space which takes into account the logarithmic response of the eye).

[0088] The CIELAB color space is used to characterize the colors of different surfaces. This space can be represented according to a geometric model with 3 orthogonal axes representing the L*a*b* dimensions. Each color thus has very precise L*a*b* coordinates specific to it: • L* representing lightness on an axis expressed as a percentage, from black: 0 to white: 100 • a* the axis ranging from green: -128 to red: +128 • b* the axis going from blue: -128 to yellow: +128

[0089] The coating according to the invention is a fluoropolymer-based coating.

[0090] The fluoropolymer(s) may be in the form of a powder or aqueous dispersion, or mixtures thereof.

[0091] Advantageously, the fluoropolymer(s) may be selected from the group comprising polytetrafluoroethylene (PTFE), tetrafluoroethylene and perfluoropropyl vinyl ether (PFA) copolymers, tetrafluoroethylene and hexafluoropropene (FEP) copolymers, polyvinylidene fluoride (PVDF), tetrafluoroethylene and polymethyl vinyl ether (MVA) copolymers, tetrafluoroethylene, polymethyl vinyl ether and fluoroalkyl vinyl ether (TFE / PMVE / FAVE) terpolymers, ethylene tetrafluoroethylene (ETFE), and mixtures thereof.

[0092] Advantageously, the fluoropolymer(s) can be selected from polytetrafluoroethylene (PTFE), tetrafluoroethylene and perfluoropropyl vinyl ether (PFA) copolymers, tetrafluoroethylene and hexafluoropropene (FEP) copolymers, a mixture of PTFE and PFA (PTFE / PFA), a mixture of PTFE and FEP (PTFE / FEP).

[0093] Preferably, the fluoropolymer(s) may represent from 10 to 99% by mass, preferably from 50 to 98% by mass, of the total dry mass of the non-stick coating composition.

[0094] Preferably the coating comprises one or more finishing layers arranged above layer (a), advantageously made of one or more fluoropolymers.

[0095] All continuous layers such as continuous layers (a) can be applied by spray, screen printing, roller, etc.

[0096] The decorations can be applied by any technique well known to those skilled in the art, such as screen printing, pad printing, digital printing, spray or roller.

[0097] According to one embodiment, the copper source is added simultaneously to the pigment(s) during the preparation of layer (a), preferably by co-milling. Advantageously, copper oxide or copper gluconate is milled with the pigment(s) to prepare layer (a).

[0098] According to another embodiment, the copper source is added after the pigment(s) during the preparation of layer (a).

[0099] The coating according to the invention may advantageously comprise one or more decorations.

[0100] The decorations may be in the form of adjacent non-overlapping motifs. According to another embodiment, the decorations are partially overlapping.

[0101] Preferably, the decorations overlap, either because one of the decorations is a continuous layer and another decoration covers it in the form of motifs, or because the decorations are in the form of overlapping motifs. The term "layers" refers to Overlapping layers are partially or completely superimposed. These layers can appear as decorations with partially overlapping patterns, for example concentric discs.

[0102] The primary layer(s) may include a bonding resin, in particular when the substrate is mechanically treated.

[0103] Preferably, the bonding resin(s) is / are chosen from the group consisting of polyamide imides (PAI), polyether imides (PEI), polyamides (PA), polyimides (PI), polyetherketones (PEK), polyetheretherketones (PEEK), polyaryletherketones (PAEK), polyethersulfones (PES), and polyphenylene sulfide (PPS), polybenzimidazoles (PBI), tannins, and mixtures thereof.

[0104] Another object of the present invention relates to a household article comprising a substrate, preferably metallic, covered with a coating according to the invention.

[0105] Preferably, said household article is a cooking article and said coating covers the side receiving the food.

[0106] The support for the article may be made of plastic, metallic material, glass, ceramic or terracotta. Advantageously, metallic supports usable within the scope of the present invention include supports made of anodized or unanodized aluminum or aluminum alloy, or of polished, brushed or micro-blasted, sandblasted, chemically treated aluminum or aluminum alloy, or of polished stainless steel, or of cast iron or aluminum, or of hammered or polished titanium or copper.

[0107] Examples of household articles that can be used in the context of the present invention include fryer vats, fondue or raclette pans or casseroles, the vat of a fryer or bread machine, the bowl of a blender, a hair straightener (said coating is intended to cover the plates of said hair straightener) and an iron (said coating is intended to cover the sole of said iron).

[0108] Preferably, said household article is a cooking article, preferably chosen from the group consisting of saucepan, frying pan, stockpot, wok, sauté pan, crepe pan, grill, griddle, raclette machine, pot, casserole dish, and said coating is intended to be in contact with food.

[0109] In the fields of application envisaged for the present invention, a heating article of the type cooking article or a heating article of the type iron is typically used in a temperature range between 10 °C and 300 °C.

[0110] The use according to the invention can catalyze the degradation of by-products from said coating during the sintering step of its manufacturing process.

[0111] Another object of the present invention relates to a method for preparing a fluoropolymer-based coating for the surface of a household article comprising the following steps in this order: - application on a metallic substrate of at least one primary layer comprising one or more fluoropolymer(s) and one or more bonding resin(s), the first primary layer being intended to coat a surface of the metallic substrate of said household article, - application of at least one layer (a) comprising at least one pigment, - possibly application of at least one finishing coat,

[0112] characterized by a step of adding in at least one layer of said coating a copper source to catalyze the degradation of by-products from said coating during its manufacturing process.

[0113] Layer (a) may be a decoration. Layer (a) may also be a primary layer, preferably the last primary layer starting from the substrate.

[0114] Preferably, the copper source is added in a content between 0.01 and 75% relative to the total weight of each layer comprising said source of copper in the wet state, preferably between 0.05 and 30%, more preferably between 0.1 and 15%, even more preferably between 0.25 and 7.5%. EXAMPLES

[0115] Several coatings according to the invention have been produced: coating without bonding resin as a color reference for the decorations, coatings with PAI showing the alteration of the decoration, decoration without copper source and decorations with copper source.

[0116] The formulations of the different constituent layers of these coatings are detailed below. Formulation of primary layers

[0117] Preparation of the paste containing PAI (PP650) and of the preparation containing TiO2 (PPTiO2):

[0118] [Tables 1] Composition (% w) PP650 PPTiO2 Resin PAI 10.32 - TiO2 - 49.85 Solvent 37.42 Dispersant - 5.20 Antifoam - 0.80 Base 4.03 0.40 Thickener - 0.40 Water 48.22 43.35 Total 100.00 100.00

[0119] The following different primary layers were formulated: a primary without PAI (P700), a primary 1 with PAI (P740), a primary 2 with PAI and a copper source (P2), a primary 2 with PAI and without a copper source (P640), a primary with PAI, TiO2 without a copper source (P3) and a primary with PAI, TiO2 with a copper source (P4).

[0120] [Tables2] Composition (% wet m) P700 P740 P2 P640 P3 P4 PTFE Dispersion 31.15 9.70 40.00 40.00 40.00 40.00 PFA Dispersion 12.38 - 11.04 11.04 11.04 11.04 FEP Dispersion - 7.04 - - - - Derussol 3.64 5.30 5.09 5.09 - - PPTiO2 - - - - 6.14 6.14 Colloidal Silica 11.99 18.73 3.55 3.55 3.55 3.55 Monopropylene glycol - 3.45 2.16 3.16 3.16 2.16 Additive - 0.98 1.42 1.42 1.42 1.42 Thickener 0.88 1.52 1.42 1.42 1.42 1.42 Copper gluconate solution 2 0% - - 13.08 - - 13.08 Demineralized water 39.01 6.71 - 13.08 13.08 - PP650 - 39.93 20.19 20.19 20.19 20.19 Filler - 6.08 1.05 1.05 - 1.00 Ammonia 1 0.25% 0.95 0.56 1.00 - - - Total 100.00 100.00 100.00 100.00 100.00 100.00

[0121] [Tables3] Composition (% dry matter) P700 P740 P2 P640 P3 P4 PTFE Dispersion 63.60 21.40 67.80 68.80 63.67 61.12 PFA Dispersion 21.10 - 15.50 15.80 14.64 14.06 FEP Dispersion - 13.00 - - - - Derussol 3.10 4.10 3.60 3.60 - - PPTiO2 - - - - 13.50 12.96 Colloidal Silica 12.20 20.80 3.00 3.00 2.83 2.71 Monopropylene glycol - - - - - - Additive - - - - - - Thickener - - - - - - Eugenate* - - 1.40 - - 1.46 Demineralized Water - - - - - - PP650 - 14.80 5.70 5.80 5.36 5.14 Pigment - 3.40 - - - - Filler - 22.50 3.00 3.00 - - Ammonia 1 0.25% - - - - - 2.55 Total 100.00 100.00 100.00 100.00 100.00 100.00

[0122] * % cooked calculated on the basis of CuO formation Formulation of the topcoat (F8):

[0123] [Tables4] F8 Composition % m Dispersion PTFE 62.31 Dispersion FEP 30.55 Dispersion PFA 0.60 Monopropylene glycol 2.02 Base 2.02 Additive 0.86 Thickener 1.34 Flakes 0.20 Base 0.10 Total 100.00

[0124]

[0125]

[0126] Formulation of pad printing pastes with bismuth vanadate PT1: copper-free pad printing paste [Tables 5] PT1 Composition % wet weight % dry weight Grinding BiVO4 36.20 69.70 Water 16.70 - Additive 3.00 - Antifoam 0.50 - Base 0.10 - Thickener 0.20 - Binder 3.60 3.50 Post-addition Dispersion PTFE 23.20 26.80 Solvent 8.00 - Antifoam 2.00 - Thickener 2.00 - Water 3.50 - Base 1.00 - Total 100.00 100.00

[0127] PT2: pad printing paste with post-addition of a copper acetate solution

[0128] PT3: pad printing paste with post-addition of a copper gluconate solution

[0129] PT4: pad printing paste with post-addition of copper oxide (CuO)

[0130] [Tableauxô] Composition (% wet weight) PT2 PT3 PT4 PT1 85.40 83.00 99.50 Copper acetate 20% 3.80 - - Copper gluconate 20% - 7.50 - Copper oxide - - 0.50 Thickener 3.80 2.50 - Additive 6.00 6.00 - Base 1.00 1.00 - Total 100.00 100.00 100.00

[0131] [Tables?] Composition (% dry matter) PT2 PT3 PT4 PT1 99.26 99.24 99.04 Copper acetate* 0.74 - - Copper gluconate* - 0.76 - Copper oxide - - 0.96 Thickener - - - Additive - - - Base - - - Total 100.00 100.00 100.0

[0132] * % cooked calculated on the basis of CuO formation

[0133] PT5: pad printing paste with co-grinding of pigment and copper acetate

[0134] PT6: Pad printing paste with co-milling of pigment and copper gluconate

[0135] PT7: Pad printing paste with co-grinding of pigment and copper oxide

[0136] [Tables8] Composition (% wt.) PT5 PT6 PT7 BiVO4 Grinding 36.20 36.20 36.20 Copper Acetate 0.60 - - Copper Gluconate - 1.50 - Copper Oxide - - 0.50 Water 12.80 12.50 16.20 Additive 3.00 3.00 3.00 Antifoam 0.50 0.50 0.50 Base 2.40 1.80 0.10 Thickener 1.20 1.20 0.20 Binder 3.60 3.60 3.60 Post-addition PTFE Dispersion 23.20 23.20 23.20 Solvent 8.00 8.00 8.00 Antifoam 2.00 2.00 2.00 Thickener 2.00 2.00 2.00 Water 3.50 3.50 3.50 Base 1.00 1.00 1.00 Total 100.00 100.00 100.00

[0137] [Tables9] Composition (% dry matter) PT5 PT6 PT7 BiVO4 Grinding 69.37 69.37 69.07 Copper acetate* 0.50 - - Copper gluconate* - 0.50 - Copper oxide - - 0.95 Water - - - Additive - - - Antifoam - - - Base - - - Thickener - - - Binder 3.45 3.45 3.43 Post-addition PTFE Dispersion 26.68 26.68 26.55 Solvent - - - Antifoam - - - Thickener - - - Water - - - Base - - - Total 100.00 100.00 100.00

[0138] * % cooked calculated on the basis of CuO formation

[0139] Formulation of pad printing pastes with silver iodide

[0140] PT8: Silver iodide pad printing paste without copper source

[0141] [Tables 10] PT 8 Composition % wet weight % dry weight Grinding Agi 12.30 27.40 Water 10.80 - Additive 1.20 - Antifoam 0.50 - Base 0.10 - Thickener 0.20 - Post-addition Dispersion PTFE 54.20 72.60 Solvent 10.80 - Antifoam 1.80 - Thickener 2.00 - Water 5.10 - Base 1.00 - Total 100.00 100.0

[0142] PT9: silver iodide pad printing paste with copper source

[0143] [Tables 11] PT9 Composition % wet weight % dry weight PT8 83.00 99.42 Copper gluconate 20% 6.20 0.58* Thickener 3.80 - Additive 6.00 - Base 1.00 - Total 100.00 100.00

[0144] * % cooked calculated on the basis of CuO formation

[0145] PT10: Copper-free titanium pad printing paste

[0146] [Tables 12] PT 10 Composition % wet m % dry m Grinding TiO2 12.51 28.02 Water 10.84 - Additive 1.25 - Antifoam 0.20 - Base 0.10 - Thickener 0.10 - Post addition Dispersion PTFE 53.55 71.98 Solvent 10.00 - Antifoam 1.83 - Thickener 2.29 - Water 6.43 - Base 0.90 - Total 100.00 100.0

[0147] PT11: Titanium pad printing paste with copper source

[0148] [Tables 13] PT11 Composition % wet weight % dry weight PT10 84.05 99.18 Copper gluconate 25% 7.12 0.82* Thickener 6.31 - Additive 1.57 - Base 0.95 - Total 100.00 100.00

[0149] * % cooked calculated on the basis of CuO formation

[0150] PT12: Copper-free glitter pad printing paste

[0151] [Tables 14] PT12 Composition % wet % dry Water 58.67 - Propylene glycol 15.12 - Dispersant 1.57 - Antifoam 1.06 - Iriodin 111 (Merck) glitter 10.58 100.00 Base 4.85 - Thickener 8.15 - Total 100.00 100.00 PT13: glitter pad printing paste with copper source [Tables 15]

[0152]

[0153]

[0154]

[0155]

[0156]

[0157] PT13 Composition % wet weight % dry weight PT12 76.8 94.92 Copper gluconate 20% 12.4 5.08* Thickener 3.8 - Additive 6.0 - Base 1.0 - Total 100.00 100.00 * % cooked calculated based on CuO formation Several coatings were applied using the layers described above: - Either the coatings are composed of two primer layers 1 and 2, then a pad-printing paste-based layer and finally a finishing layer. - Either the coatings are composed of two primary layers and one finishing layer. The AE* of the pad-based layer is then studied, the color reference of the coating is considered to be that of the coating made without tack resin. The AE* values ​​are defined by the CIE1976 formula in the CIELAB color space:

[0158] [Math.5]

[0159] Li*, ai* and bi* characterizing the L*a*b values ​​of the decor with a coating without bonding resin or without copper source.

[0160] L2*, a2* and b2* characterizing the L*a*b values ​​of the decor with a coating with bonding resin or with copper source.

[0161] The results are summarized in the tables below.

[0162] [Tables 16] Primer Coating 1 Primer 2 PT Finish AE* 1 Without resin P700 P700 PT2 F8 11.1 2 With resin P740 P640 PT2 F8 3 Without resin P700 P700 PT3 F8 3.0 4 With resin P740 P640 PT3 F8 5 Without resin P700 P700 PT4 F8 12.3 6 With resin P740 P640 PT4 F8 7 Without resin P700 P700 PT5 F8 5.0 8 With resin P740 P640 PT5 F8 9 Without resin P700 P700 PT6 F8 4.9 10 With resin P740 P640 PT6 F8 11 Without resin P700 P700 PT7 F8 4.1 12 With Resin P740 P640 PT7 F8 13 Without resin P700 P700 PT 9 F8 3.7 14 With resin P740 P640 PT 9 F8 15 Without resin P700 P700 PT 8 F8 4.2 16 With resin P740 P2 PT 8 F8 17 Without resin P700 P700 PT 1 F8 28.6 18 With resin P740 P640 PT 1 F8 19 Without resin P700 P700 PT 8 F8 21.0 20 With resin P740 P640 PT 8 F8 21 Without resin P700 P700 PT 10 F8 21.0 22 With Resin P740 P640 PT 10 F8 23 Without Resin P700 P700 PT 11 F8 2.0 24 With Resin P740 P640 PT 11 F8 25 Without Resin P700 P4 - F8 2.0 26 With Resin P740 P4 - F8 27 Without Resin P700 P3 - F8 21.0 28 With Resin P740 P3 - F8 29 Without Resin P700 P700 PT 12 F8 31.0 30 With Resin P740 P640 PT 12 F8 31 Without Resin P700 P700 PT 13 F8 3.2 32 With Resin P740 P640 PT 13 F8

[0163] [Tables 17] Primer Coating 1 Primer 2 PT Finish AE* 17 Without resin P700 P700 PT 1 F8 3.0 11 Without resin P700 P700 PT7 F8 18 With resin P740 P640 PT 1 F8 26.0 12 With resin P740 P640 PT7 F8 21 Without resin P700 P700 PT 10 F8 4.0 23 Without resin P700 P700 PT 11 F8 22 With resin P740 P640 PT 10 F8 22.0 24 With resin P740 P640 PT 11 F8

[0164] It is observed that AE*(17-18), AE*(19-20) and AE*(21-22) are largely higher than the other AE* values ​​in Table 16, these comparative examples carried out The values ​​without the incorporation of a copper source represent the reference values ​​for color alteration occurring during the manufacturing process. Furthermore, when two coatings are manufactured with an adhesion resin and prepared with two different pad printing pastes, one without a copper source and the other with a copper source, the color difference is significant (Table 17: AE*(12-18) = 26.0). Coatings manufactured without a copper source therefore undergo a significant color change during their production compared to those containing a copper source. Consequently, the copper source catalyzes the degradation of byproducts from the primary layers during manufacturing. These results are observable regardless of the pigments used, for example for TiO2: AE*(22-24) = 22.0, Table 17, or for silver iodide: AE*(13-14) = 3.7 compared to AE*(19-20) = 21.0, Table 16.Furthermore, the AE*(15-16) in Table 16 demonstrates that the copper source can be introduced into a primary layer (P2) as well as into a pad printing paste.

Claims

Claims

1. Use of a copper source in a fluoropolymer-based non-stick coating of the surface of a household article to catalyze the degradation of by-products from said coating during its manufacturing process, wherein the coating comprises in this order: - at least one primer layer comprising one or more fluoropolymer(s) and one or more bonding resin(s), the first primer layer being intended to coat a surface of the metal substrate of said household article, - at least one decorative layer (a) comprising at least one pigment and a copper source.

2. Use of a copper source according to claim 1 to avoid the change of color of the decorative layer (a), it being understood that the maintenance of the color of the decorative layer (a) in said coating corresponds to an AE* of the decorative layer (a) less than 10.0 between the coating according to claim 1 and the coating according to claim 1 without bonding resin, AE* being defined by the CIE1976 formula in the CIELAB color space: △ E* = (a^ Li*, ai* and bi* characterizing the L*a*b values of the decorative layer (a) of the coating according to claim 1 without bonding resin, L2*, a2* and b2* characterizing the L*a*b values of the decorative layer (a) of the coating according to claim 1.

3. Use according to any one of the preceding claims in which the copper is in oxidation state II.

4. Use according to any one of the preceding claims in which the source of copper is chosen from: organic copper salts, inorganic copper salts, copper oxides, alone or in a mixture, preferably from organic salts and copper oxides alone or in a mixture, more preferably from copper oxide, copper acetate or copper gluconate, alone or in a mixture.

5. Use according to any one of claims 1 to 4 in which layer (a) comprises at least one pigment chosen from the list consisting of inorganic pigments whose Color Index Constitution Number (CICN) is between 77000-77999 according to the Color Index International, Fourth Edition, Agi, Bi2O3, a pigment of type (Bii_xAx)(Vi_yMy)04 and mixtures thereof, in which: - 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 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, - A and M are different from each other.

6. Use according to the preceding claim in which the pigment content in layer (a) is between 0.1 and 100% by weight relative to the weight of said layer in the dry state, preferably between 0.2 and 80% by weight.

7. Use according to claim 5 characterized in that the AE* of the pigment (Bii.xAx)(Vi.yMy)04 in said coating is greater than 11 between room temperature and 150°C, AE* being defined by the CIE1976 formula in the CIELAB color space: VX Ad J- Z \ Zj X / 1 Zi -L 1 Li*, ai* and bi* characterizing the L*a*b values of said compound at room temperature L2*, a2* and b2* characterizing the L*a*b values of said compound at 150°C.

8. Use according to claims 5 or 7 characterized in that the AE* of said pigment (Bi1.xAx)(Vi.yMy)04 in said coating is greater than 15 between room temperature and 200°C, AE* being defined by the CIE1976 formula in the CIELAB color space: A 1 / = ^(.^-1. / ^+(3 / -37)2+^ / -11^2 Li*, ai* and bi* characterizing the L*a*b values of said compound at room temperature L2*, a2* and b2* characterizing the L*a*b values of said compound at 200°C.

9. Use according to any one of claims 1 to 8, the coating comprising one or more finishing layers arranged above layer (a), preferably consisting of one or more fluoropolymers.

10. Use according to any one of claims 5 and 7 to 8 in which x and y are 0.

11. Use according to any one of claims 5 and 7 to 8 wherein A and / or M is an alkali metal chosen from Li, Na, K, Rb, Cs, A and M being different from each other.

12. Use according to any one of claims 5 and 7 to 8 in which A and / or M is an alkaline earth metal chosen from Be, Mg, Ca, Sr, Ba, A and M being different from each other.

13. Use according to any one of claims 5 and 7 to 8 wherein A and / or M is a transition metal selected from Sc, Ti Cr, Mn, Fe, Co, Ni, Cu, Y, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Ta, W, Ir, A and M being different from each other.

14. Use according to any one of claims 5 and 7 to 8 in which A and / or M is a poor metal chosen from Al, Zn, Ga, In, Sn, A and M being different from each other.

15. Use according to any one of claims 5 and 7 to 8 wherein A and / or M is a metalloid chosen from B, Si, Ge, Sb, A and M being different from each other.

16. Use according to any one of claims 5 and 7 to 8 in which A and / or M is a lanthanide chosen from La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, A and M being different from each other.

17. Use according to any one of claims 5 to 16 wherein the copper source is added simultaneously to the pigment(s) during the preparation of layer (a), preferably by co-grinding.

18. Use according to any one of claims 5 to 16 in which the copper source is added subsequently to the pigment(s) during the preparation of layer (a).

19. Use according to any one of claims 1 to 18 in which the coating bonding resin(s) is(are) chosen from the group consisting of polyamide imides (PAI), polyether imides (PEI), polyamides (PA), polyimides (PI), polyetherketones (PEK), polyetheretherketones (PEEK), polyaryletherketones (PAEK), polyethersulphones (PES), polyphenylene sulfide (PPS), polybenzimidazoles (PBI), tannins, and mixtures thereof.

20. Use according to any one of the preceding claims wherein the fluoropolymer(s) of the coating is(are) selected from the group consisting of polytetrafluoroethylene (PTFE), copolymers of tetrafluoroethylene and perfluoropropylvinylether (PFA), copolymers of tetrafluoroethylene and hexafluoropropene (FEP), polyvinylidene fluoride (PVDF), copolymers of tetrafluoroethylene and polymethylvinylether (MVA), terpolymers of tetrafluoroethylene, polymethylvinylether and fluoroalkylvinylether (TFE / PMVE / FAVE), ethylene tetrafluoroethylene (ETFE), and mixtures thereof.

21. Use according to any one of claims 1 to 20 in which the copper content in layer (a) is between 0.01 and 75% relative to the total weight of said layer in the wet state, preferably between 0.05 and 30%, more preferably between 0.1 and 15%, even more preferably between 0.25 and 7.5%.

22. Fluoropolymer-based coating of the surface of a household article comprising in this order: - at least one primer layer comprising one or more fluoropolymer(s) and one or more bonding resin(s), the first primer layer being intended to coat a surface of the metal substrate of said household article, - at least one decorative layer (a) comprising at least one pigment and a source of copper.

23. Coating according to claim 22 characterized in that the copper is present in the decorative layer (a) in a content of between 0.01 and 30% relative to the total weight of the decorative layer (a) in the dry state, preferably between 0.05 and 30%, more preferably between 0.1 and 15%, even more preferably between 0.25 and 10%, better still between 0.30 and 7.5%.

24. A household article comprising a substrate, preferably metallic, covered with a coating defined in any one of claims 22 to 23.

25. Household article according to claim 24, characterized in that it is a culinary article and in that the coating defined in any one of claims 22 to 23 covers the food receiving face.

26. Culinary article according to claim 25, the substrate being made of anodized or non-anodized aluminum or aluminum alloy, or polished, brushed or micro-blasted, sandblasted, chemically treated aluminum or aluminum alloy or polished stainless steel, or cast iron or aluminum, or hammered or polished titanium or copper.

27. Culinary article according to claim 25 or 26, said culinary article being chosen from the group consisting of saucepan, frying pan, stewpan, wok, sauté pan, crepe pan, grill, griddle, raclette machine, pot, casserole, and said coating is intended to be placed in contact with food.

28. Household article according to claim 24, characterized in that it is an iron and in that the coating defined in any one of claims 22 to 23 covers the soleplate of said iron.

29. Household article according to claim 24, characterized in that it is a hair straightener and in that the coating defined in any one of claims 22 to 23 covers the plates of said hair straightener.

30. A method for preparing a fluoropolymer-based coating for the surface of a household item comprising the following steps in this order: - application to a metal substrate of at least one primer layer comprising one or more fluoropolymer(s) and one or more bonding resin(s), the first primer layer being intended to coat a surface of the metal substrate of said household item, - application of at least one decorative layer (a) comprising at least one pigment, - optionally application of at least one finishing layer, characterized by a step of adding to the decorative layer (a) of said coating a source of copper to catalyze the degradation of the by-products from said coating during its manufacturing process.

31. Method according to the preceding claim, characterized in that the copper source is added in a content of between 0.01 and 75% relative to the total weight of the decorative layer (a) comprising said source of copper in the wet state, preferably between 0.05 and 30%, more preferably between 0.1 and 15%, even more preferably between 0.25 and 7.5%.