Improved non-stick coating

Abstract

The object of the present invention is to provide a non-stick coating for household articles (Bi 1-x A x )(V 1-y M y ) Use of O4 to reduce or prevent color change of the coating during its manufacturing process, wherein x is equal to 0 or x is 0.001 to 0.999, y is equal to 0 or y is 0.001 to 0.999, and A and M are selected from the group consisting of nitrogen, phosphorus, alkali metals, alkaline earth metals, transition metals, poor metals, metalloids, or lanthanides, and A and M are different from each other.

Description

[Technical Field]

[0001] The present invention relates to non-stick coatings for household items, preferably cookware. [Background technology]

[0002] Non-stick household articles with fluoropolymer-based coatings currently consist in particular of PTFE fluoropolymers, but can also incorporate one or more binding resins such as PAI, PES, PAEK (polyaryletherketone), tannins, and / or organic additives such as acrylic derivatives. Summary of the Invention [Problem to be solved by the invention]

[0003] A drawback of these resins and their additives is that they tend to partially decompose when PTFE is sintered, generating decomposition by-products that contribute to an overall yellowing of the article, which becomes even more noticeable when a light-colored decor is applied between the primer and finish coats.

[0004] The compound BiVO4 is now known as a photocatalyst that can decompose organic compounds and thus remove pollution from the atmosphere. However, to be activated, this catalyst requires light, and the decomposition rate is often very long (several hours).

[0005] Recently, it has been shown that BiVO4 can be used to completely decompose methylbenzene by combining temperature and light irradiation. However, there is no mention that BiVO4 can only thermally decompose methylbenzene (Chinese Patent Application Publication No. 102008892).

[0006] Surprisingly, the inventors have observed that these yellowing phenomena, which typically occur at the end of the high-temperature manufacturing process of non-stick coatings, can be resolved by adding BiVO4 to one of the coating layers. The inventors have actually observed that by adding BiVO4, a yellow decoration can be obtained without degrading the original color. Thus, BiVO4 protects the color of the coating to which it is added. Furthermore, the inventors have shown that it can also protect the color of coatings placed on top of the one to which it is added. [Means for solving the problem]

[0007] Summary of the Invention The first subject of the present invention is the use of (Bi) in non-stick coatings for household articles. 1-x A x )(V 1-y M y ) Use of O4 to reduce or prevent color changes in the coating during its manufacturing process, 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, alkali metals, alkaline earth metals, transition metals, poor metals, metalloids or lanthanides; A and M are different from each other.

[0008] definition "Room temperature" is understood to mean a temperature between 18 and 30°C.

[0009] In the sense of the present invention, a "coat" should be understood to mean a continuous or discontinuous coating. A continuous coating (also called a monolithic coating) is a single whole that forms an all-solid color that completely covers the surface on which it is placed. A discontinuous coating (or a non-monolithic coating) can comprise several parts and is therefore not a single whole.

[0010] "Primer coat", "bond coat", "bond primer" are understood to mean all coats from the first coat applied directly to the support, also called the substrate (this coat preferably adheres well to the support and gives all its mechanical properties: hardness, scratch resistance to the coating) to the final coat before the first decorative coat.

[0011] "Finish coat" or "finish" is understood to mean a continuous, transparent surface coat that makes the decorative coating appear intact while protecting it from mechanical damage and imparting its non-stick properties to the coating.

[0012] "Decoration" or "decorative coating" is understood to mean one or more continuous or discontinuous coatings comprising a pigment composition. The decoration may be in the form of one or more patterns and one or more colors. The decoration is clearly visible to the user with the naked eye at the normal use distance of the household item.

[0013] The expression "household goods" should be understood to mean cooking utensils and household electrical appliances.

[0014] The appliances in question are intended to generate heat.

[0015] In the sense of the present invention, "cookware" is to be understood to mean an object intended for cooking, which for this purpose is intended to be subjected to a heat treatment.

[0016] In the sense of the present invention, an "object intended to undergo a heat treatment" is to be understood as an object that is heated by an external heating system, such as a frying pan, a saucepan, a sauté pan, a wok or a barbecue grill, and that is capable of transferring the amount of heat provided by this external heating system to a material or food that comes into contact with said object.

[0017] In the sense of the present invention, "object intended to generate heat" should be understood to mean a heating object having its own heating system, such as a clothes iron, a hair straightener, a steam generator, an electric kettle or a cooking appliance.

[0018] A "fluoropolymer-based coating" is understood to mean a coating that contains one or more fluoropolymers in one or more of its coats.

[0019] In the sense of the present invention, "sol-gel coating" is understood to mean a coating synthesized by the sol-gel route from a solution based on liquid precursors, which is transformed into a solid by a series of chemical reactions (hydrolysis and condensation) at low temperature. The coatings thus obtained can be organo-mineral or all-mineral.

[0020] In the sense of the present invention, "organo-mineral coating" is understood to mean a coating whose network is essentially inorganic but which contains organic groups, in particular due to the precursors used and the curing temperature of the coating.

[0021] In the sense of the present invention, an "all-mineral coating" is intended to mean a coating made entirely of inorganic materials, without organic groups. Such a coating can be obtained by a sol-gel route with a curing temperature of at least 400°C, or from precursors of the tetraethoxysilane (TEOS) type with a curing temperature that can be below 400°C. [Brief explanation of the drawings]

[0022] [Figure 1] Figure 1 shows the pattern distribution diagram for two decorative configurations. 1A is an adjacent, non-overlapping pattern. 1B is a partially overlapping pattern. 1C is an overlapping pattern. DETAILED DESCRIPTION OF THE INVENTION

[0023] Detailed Description The first subject of the present invention is the use of (Bi) in non-stick coatings for household articles. 1-x A x )(V 1-y M y ) O4 to reduce or prevent color changes in the coating during its manufacturing process, 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, alkali metals, alkaline earth metals, transition metals, poor metals, metalloids or lanthanides; A and M are different from each other.

[0024] (Bi 1-x A x )(V 1-y M y )O4 is added to one or more coats of the non-stick coating.

[0025] Preferably, (Bi 1-x A x )(V 1-y M y The amount of O4 in the coating to which it is added is 0.1 to 100% by weight, preferably 0.2 to 80% by weight, more preferably 0.5 to 70% by weight, based on the weight of the coating in the dry state. 1-x A x )(V 1-y M y )O4 can be applied pure and continuous or discontinuously.

[0026] Advantageously, (Bi 1-x A x )(V 1-y M y )O4 compound is (Bi 1-x A x )(V 1-y M y It exists in the form of particles made of Bi )O4 compounds. 1-x A x)(V 1-y M y "Particle morphology consisting of a (Bi)O4 compound" means that the particles are purely (Bi)O4 1-x A x )(V 1-y M y )O4 compounds. They are therefore uncoated. Advantageously, they are rough.

[0027] During the manufacturing process, the coating may be subjected to high temperatures, for example, 150-450°C.

[0028] Such high temperatures can cause the coating to change color.

[0029] The term "reducing or preventing color change" preferably means reducing or preventing color change that is visible to the naked eye.

[0030] Preferably, (Bi 1-x A x )(V 1-y M y The )O4 compound exhibits a monolithic schellite crystal morphology at room temperature.

[0031] Preferably, x and y are 0, i.e. the invention relates to the use of bismuth vanadate (BiVO4). Advantageously, the BiVO4 compound is used which is in monolithic schellite crystalline form at room temperature.

[0032] Bismuth vanadate, a yellow inorganic compound with the formula BiVO4, is widely used due to its color properties and non-toxicity. It is listed in the Color Index International database as QI Pigment Yellow 184 and is sold by the companies Heubach (Vanadur®), BASF (Sicopal®), FERRO (Lysopac), and Bruchsaler Farbenfabrik (Brufasol®), among others.

[0033] This compound has been the subject of much research due to its intense color and its thermochromism. Many synthetic routes have been considered for the production of BiVO4 nanoparticles, including sol-gel synthesis, precursor pyrolysis, hydrothermal synthesis, solvothermal synthesis, and vapor deposition. Hydrothermal synthesis can be mechanistically complex due to the simultaneous formation of stable and unstable phases upon rapid heating in a pressurized autoclave. The rich phases and complex phase diagrams of the products obtained by hydrothermal synthesis make it difficult to crystallographically form and stabilize either phase.

[0034] The second, more common synthesis route is solid-state sintering, which has the advantage of easily obtaining large-scale, highly crystalline powders at low cost. BiVO4 particles can be obtained by annealing a mixture of bismuth and vanadium salts at high temperatures. The resulting microstructure (particle size, morphology, crystallinity) and optional doping elements may affect the band gap of BiVO4, thereby altering its initial color and / or thermochromism.

[0035] If A and M are different from each other, When A is an alkali metal, it may be selected from Li, Na, K, Rb and Cs; When M is an alkali metal, it may be selected from Li, Na, K, Rb and Cs; When A is an alkaline earth metal, it may be selected from Be, Mg, Ca, Sr and Ba; When M is an alkaline earth metal, it may be selected from Be, Mg, Ca, Sr and Ba; When A is a transition metal it may be selected from Sc, Ti, Cr, Mn, Fe, Co, Ni, Cu, Y, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Ta, W and Ir; When M is a transition metal it may be selected from Sc, Ti, Cr, Mn, Fe, Co, Ni, Cu, Y, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Ta, W and Ir; When A is a poor metal, it can be selected from Al, Zn, Ga, In, Sn; When M is a poor metal, it may be selected from Al, Zn, Ga, In, Sn; When A is a metalloid, it may be selected from B, Si, Ge, Sb; When M is a metalloid, it may be selected from B, Si, Ge, Sb; When A is a lanthanide, it may be selected from La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu; When M is a lanthanide, it can be selected from La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu. Preferably, A and M, which are different from each other, are B and / or Mg.

[0036] Preferably, the coating comprises, in the following order from the side of the substrate of the household article to which it is applied: one or more primer coats, optionally one or more continuous or discontinuous decorative coats, and one or more finish coats.

[0037] Preferably, said coating comprises, from the face of the substrate of the household article, in the following order: 1 or 2 primer coats, optionally a decorative coat and a finish coat.

[0038] In the undecorated configuration, (Bi 1-x A x )(V 1-y M y )O4 is added to at least one primer coat and / or at least one top coat. It is added, for example, to a primer coat to protect the top coat against color change. It is added, for example, to one or more top coats to protect it or them against color change.

[0039] According to another embodiment, the coating according to the invention is an organo-mineral or all-mineral sol-gel (SG) coating. These coatings, synthesized by the sol-gel route from metal polyalkoxylate type precursors, generally have a hybrid network of silica with grafted alkyl groups. The sol-gel (SG) composition comprises at least one colloidal metal oxide and at least one metal alkoxide type precursor.

[0040] The metal alkoxide is preferably a colloidal metal oxide selected from colloidal silica and / or colloidal alumina.

[0041] Metal alkoxides are preferably used as precursors selected from the group consisting of: precursors M1(OR1)n corresponding to the general composition M, General composition M2 (OR2) (n-1) a precursor corresponding to R2', and General composition M3 (OR3) (n-2) a precursor corresponding to R3'2, R1, R2, R3 or R3' represents an alkyl group. R2' represents an alkyl or phenyl group; n is an integer corresponding to the maximum valence of metal M1, M2, or M3; M1, M2, or M3 represents a metal selected from Si, Zr, Ti, Sn, Al, Ce, V, Nb, Hf, Mg, or Ln.

[0042] Advantageously, the metal alkoxide of the sol-gel solution is an alkoxysilane.

[0043] Alkoxysilanes that can be used in the sol-gel solution of the method of the present invention can include, among others, methyltrimethoxysilane (MTMS), tetraethoxysilane (TEOS), methyltriethoxysilane (MTES), dimethyldimethoxysilane, and mixtures thereof.

[0044] Preferably, alkoxysilanes MTES and TEOS are used because they have the advantage of not containing methoxy groups. In fact, hydrolysis of the methoxy groups leads to the formation of methanol in the sol-gel formulation, which, given its toxicity, requires additional precautions during application. In contrast, hydrolysis of the ethoxy groups only produces ethanol, which is a more favorable class, making the conditions for use of sol-gel coatings more restrictive.

[0045] The formation of this sol-gel coating consists in mixing an aqueous composition A containing a colloidal metal oxide with a solution B containing a metal alkoxide, advantageously in a proportion of 40 to 75% by weight of the aqueous composition relative to the weight of the sol-gel composition (A+B), so that the amount of colloidal metal oxide represents, in dry form, 5 to 30% by weight of the sol-gel composition (A+B).

[0046] The aqueous composition A may also contain a solvent, in particular a solvent comprising at least one alcohol.

[0047] Aqueous composition A may also contain at least one silicone oil.

[0048] The aqueous composition A may also contain a pigment.

[0049] Aqueous composition A may also contain a mineral filler.

[0050] Aqueous Composition A may also contain fumed silica, the function of which is to adjust the viscosity of the sol-gel composition and / or the gloss of the dried coating.

[0051] Aqueous composition A typically contains, for a primer coating: i) 5 to 30 wt. % of at least one colloidal metal oxide, based on the total weight of aqueous composition A; ii) 0 to 20% by weight, relative to the weight of composition A, of a solvent comprising at least one alcohol; iii) optionally, 0.05 to 3% by weight, relative to the total weight of the aqueous composition A, of at least one silicone oil; iv) 5-30% pigment; v) Contains 2-30% mineral filler.

[0052] Aqueous composition A typically comprises, for the top coat: i) 5 to 30 wt. % of at least one colloidal metal oxide, based on the total weight of aqueous composition A; ii) 0 to 20% by weight, relative to the weight of composition A, of a solvent comprising at least one alcohol; iii) optionally, 0.05 to 3% by weight, relative to the total weight of the aqueous composition A, of at least one silicone oil; iv) Contains 0.1 to 1% metallic luster material.

[0053] Solution B may also contain a Brønsted or Lewis acid. Advantageously, the metal alkoxide precursor of solution B is mixed with an organic or mineral Lewis acid representing from 0.01 to 10% by weight relative to the total weight of solution B.

[0054] Specific examples of acids that can be used for mixing with the metal alkoxide precursor include acetic acid, citric acid, ethyl acetoacetate, hydrochloric acid, or formic acid. Solution B may also contain a solvent, in particular a solvent comprising at least one alcohol.

[0055] Solution B may also contain at least one silicone oil.

[0056] Solution B may also contain a metallic polish.

[0057] According to an advantageous embodiment of the process of the invention, solution B may comprise a mixture of one of the alkoxysilanes as defined above and an aluminium alcoholate.

[0058] According to this sol-gel embodiment, the coating according to the invention comprises, from the substrate side, in this order: 1 or more SG primer coatings, A decoration on at least a portion of the final primer coat comprising a BiVO4 pigment compound as defined above.

[0059] According to another embodiment, the coating according to the invention is a fluoropolymer-based coating.

[0060] The fluoropolymer(s) may be present in the form of a powder or an aqueous dispersion or a mixture thereof.

[0061] Advantageously, the fluoropolymer(s) may be chosen from the group comprising polytetrafluoroethylene (PTFE), copolymers of tetrafluoroethylene and perfluoropropyl vinyl ether (PFA), copolymers of tetrafluoroethylene and hexafluoropropene (FEP), polyvinylidene fluoride (PVDF), copolymers of tetrafluoroethylene and polymethyl vinyl ether (MVA), terpolymers of tetrafluoroethylene, polymethyl vinyl ether and fluoroalkyl vinyl ether (TFE / PMVE / FAVE), ethylene tetrafluoroethylene (ETFE) and mixtures thereof.

[0062] Advantageously, the fluoropolymer(s) may be chosen from polytetrafluoroethylene (PTFE), copolymers of tetrafluoroethylene and perfluoropropyl vinyl ether (PFA), copolymers of tetrafluoroethylene and hexafluoropropene (FEP), mixtures of PTFE and PFA (PTFE / PFA) and mixtures of PTFE and FEP (PTFE / FEP).

[0063] Preferably, the fluoropolymer(s) may represent 10 to 99% by weight, preferably 50 to 98% by weight, relative to the total dry weight of the non-stick coating composition.

[0064] Preferably, the coating includes one or more decorations.

[0065] Preferably, (Bi 1-x A x )(V 1-y M y )O4 is then added to at least one of the decorations or to the primer coat, in a particularly preferred embodiment to at least one of the decorations or to the last primer coat onto which the decoration(s) are applied.

[0066] According to the first embodiment, (Bi 1-x A x )(V 1-y M y )O4 is added to the coating to reduce or prevent color change of the coating. 1-x A x )(V 1-y M y )O4 is added to the decoration to reduce or prevent color changes of this decoration. According to a subembodiment, (Bi 1-x A x )(V 1-y M y )O4 compounds are added to the coating both to reduce or prevent color change in the coating and as pigments to color the coating.

[0067] Yellow decoration, for example, (Bi 1-x A x )(V 1-y M y )O4, and (Bi 1-x A x )(V 1-y M y )O4 is used to give the decoration a yellow color as well as to protect it from color changes. This yellow decoration is 1-x A x )(V 1-y M y )Can be made with O4.

[0068] According to a second embodiment, (Bi 1-x A x )(V 1-y M y)O4 is added to the coating to reduce or prevent color changes in other coatings, especially those placed on top of this coating. For example, (Bi 1-x A x )(V 1-y M y )O4 is added to a coating applied under the decoration, for example a primer coating, in order to reduce or prevent color changes of this decoration. 1-x A x )(V 1-y M y The O4 compound is added in an amount such that it does not color the coating to which it is added.

[0069] For example, (Bi 1-x A x )(V 1-y M y )O4 and a different pattern of yellow decoration overlapping the white pattern (see Figure 1C). 1-x A x )(V 1-y M y )O4 is used to protect the yellow decoration from color change. This yellow decoration is made by (Bi 1-x A x )(V 1-y M y )O4. "Overlapping coatings" are understood to mean coatings that are partially or completely placed on top of one another. These coatings can be in the form of decorations with partially overlapping patterns, for example concentric discs.

[0070] The decoration may be applied by any method well known to those skilled in the art, such as, for example, screen printing or pad printing.

[0071] Advantageously, the article support can be plastic, metal, glass, ceramic or terracotta. Metal supports that can be used in the context of the present invention include advantageously supports of aluminum or aluminum alloys, whether anodized or not, or polished, brushed, bead-blasted, sand-blasted or chemically treated aluminum or aluminum alloys, or polished stainless steel, or cast iron or aluminum, or titanium or hammered or polished copper.

[0072] The primer coating(s) may consist of a binding resin, especially if the substrate is to be mechanically treated.

[0073] Preferably, the binding resin(s) is selected from the group consisting of polyamideimide (PAI), polyetherimide (PEI), polyamide (PA), polyimide (PI), polyetherketone (PEK), polyetheretherketone (PEEK), polyaryterketone (PAEK), polyethersulfone (PES) and polyphenylene sulfide (PPS), polybenzimidazole (PBI), tannin.

[0074] Examples of household articles that can be used in the context of the present invention may include, inter alia, deep fryer bowls, fondue or raclette pans or pots, deep fryer or bread maker bowls, blender jars, hair iron plates (the coating is intended to cover the plates of the hair iron) and iron soleplates (the coating is intended to cover the soleplate of the iron).

[0075] Preferably, said household item is an article of cookware, preferably selected from the group consisting of a saucepan, frying pan, stew pot, wok, sauté pan, crepe maker, grill, plancha, raclette, marmite pan or casserole dish, and said coating is intended to come into contact with food.

[0076] In the field of application considered for the present invention, the heated items of the cookware type and the heating items of the iron type are usually used in a temperature range comprised between 10°C and 300°C.

[0077] The use according to the invention may make it possible to reduce or prevent color changes of the coating during the sintering step of its manufacturing process. [Example]

[0078] Example Example 1: BiVO used in accordance with the present invention 4 The process of synthesizing compounds Process 1.1 A solution of ammonium vanadate (0.1 M) in 1 M nitric acid is stoichiometrically added to a solution of bismuth nitrate (0.1 M) in 1 M nitric acid. The mixture is stirred overnight, filtered, washed with water, and dried. The powder is then annealed at 450 °C for 3 hours.

[0079] Bismuth vanadate is then obtained in the form of a bright yellow powder characterized as monoclinic by X-ray diffraction analysis.

[0080] The process is carried out at a pH <1 without the addition of alkaline agents.

[0081] Process 1.2 A stoichiometric amount of sodium metavanadate is added in powder form to a solution of bismuth nitrate (0.4 M) in 1 M nitric acid. The mixture is stirred at 80 °C for 2 hours. The precipitate is then filtered and washed with water to obtain a yellow BiVO powder in the form of monoclinic shellite. The powder is then annealed at 500 °C for 3 hours.

[0082] The process is carried out at a pH <1 without the addition of alkaline agents.

[0083] Monoclinic BiVO4 thus has ΔE=40 between room temperature and 200°C.

[0084] Example 2: BiVO 4 Compound testing The following BiVO4 compounds have been tested and compared for their effectiveness in protecting the coating they are added to from color change and in protecting adjacent coatings: BiVO4 of Example 1 BiVO4 sold as Sicopal® Yellow K1120FG (BASF)

[0085] Example 3: Composition

[0086] [Table 1]

[0087] [Table 2]

[0088] [Table 3]

[0089] [Table 4]

[0090] [Table 5]

[0091] [Table 6]

[0092] [Table 7]

[0093] [Table 8]

[0094] Example 4: Configuration a. Configuration 1: BiVO 4 No primer coating 1, BiVO of Example 1 4 Primer coating 2 with / without, and BiVO 4 White color without decoration. A primer coating 1 of composition 1a is first formed on an aluminum substrate. After drying, a primer coating 2 of composition 2b is coated on primer coating 1. After drying, a white decoration 3 of composition 3a is deposited on primer coating 2. After drying, a top coat of composition 4 is coated on primer coating 2 and the decoration. The article is then sintered at 430°C for 11 minutes.

[0095] Appearance: Decoration white with L*a*b* values ​​= 83, 0.4, 12. The decoration is protected from color changes during the process of producing the coating by BiVO4 contained in a primer coating 2 applied underneath the decoration.

[0096] In contrast, the same configuration, differing only in that the primer coating 2 is of composition 2a (without BiVO4), results in the decoration after sintering not being white but golden yellow with L*a*b* values ​​= 70.8; 2.8; 14.8.

[0097] b. Configuration 2: BiVO 4 Without two primer coatings, BiVO 4 With / without decoration Primer Coat 1 of Composition 1a is first deposited on an aluminum substrate. After drying, Primer Coat 2 of Composition 2a is coated on Primer Coat 1. After drying, a white decoration of Composition 3b is deposited on Primer Coat 2. After drying, a top coat of Composition 4 is coated on Primer Coat 2 and the decoration. The article is then sintered at 430°C for 11 minutes.

[0098] Appearance: Decoration white The L*a*b* values ​​are 83, 0.4, and 12. The decoration is protected from color changes during the coating manufacturing process by the BiVO4 contained in the decoration.

[0099] On the other hand, the same configuration (without BiVO4) except that the decoration is white composition 3a shows that the white decoration changes color (L*a*b* values ​​= 70.8; 2.8; 14.8).

[0100] The same composition, except that the decoration is yellow composition 3c, shows that the yellow decoration does not change color (L*a*b* values ​​= 76.1; -5.9; 72.0). This decoration is protected from color change during the coating manufacturing process by the BiVO4 contained in the decoration.

[0101] The same composition, except that the decoration is yellow (composition 3d), shows that the yellow decoration changes color: it becomes brown (L*a*b* values ​​= 56.4; 1; 42.2). The BiVO4 pigment (Sicopal® K1120FG) in composition 3d is encapsulated, i.e., the BiVO4 particles are covered. The BiVO4 does not fulfill its catalytic role because the encapsulation prevents it from coming into contact with decomposition by-products.

[0102] c. Configuration 3: BiVO 4 Two primer coatings without, BiVO of Example 1 4 A yellow decoration containing a second decoration placed on top of the first. Primer coating 1 of composition 1a is first deposited on the aluminum substrate. After drying, primer coating 2 of composition 2a is coated on primer coating 1. After drying, a yellow decoration comprising composition 3c is deposited on primer coating 2. After drying, a white decoration of composition 3a is deposited on the previous yellow decoration. After drying, a top coat of composition 4 is coated on primer coating 2 and the decoration. The article is then sintered at 430°C for 11 minutes.

[0103] Appearance: Decoration white The L*a*b* values ​​are 83.1, 0.4, and 12.0, respectively. The white decoration is protected from color changes during the coating manufacturing process by the BiVO4 contained in the yellow decoration applied underneath the white decoration.

[0104] The same composition, except that the second decoration is yellow (composition 3d), shows that the second yellow decoration does not change color (L*a*b* values ​​= 75.5, 1.5, 72.5). The second yellow decoration is protected from color change during the coating manufacturing process by the BiVO4 contained in the first decoration.

[0105] The same composition, except that the first decoration is yellow (composition 3d), shows that the second white decoration (composition 3a) changes color (L*a*b* values ​​= 53.9, 9.4, 27.1). The second white decoration is not protected from color change during the coating manufacturing process by the BiVO4 contained in the first decoration.

Claims

1. (Bi) in non-stick coatings for household articles 1-x A x ) (V 1-y M y ) O 4 to reduce or prevent color change of said coating when said coating is exposed to high temperatures of 150-450°C during its manufacturing process, 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, alkali metals, alkaline earth metals, transition metals, poor metals, metalloids or lanthanides; A and M are different from each other, 10. Use characterized in that (Bi1-xAx)(V1-yMy)O4 is present in the form of particles consisting of the (Bi1-xAx)(V1-yMy)O4 compound.

2. 2. The use according to claim 1, wherein x and y are 0.

3. (Bi 1-x A x ) (V 1-y M y ) O 4 3. Use according to claim 1 or 2, characterized in that the amount of is comprised in each of the coatings to which it is added, between 0.1 and 100% by weight relative to the weight of said coating in the dry state.

4. The use according to claim 3, wherein the amount of (Bi 1-x A x )(V 1-y M y )O 4 in each of the coatings to which it is added is comprised between 0.2 and 80% by weight relative to the weight of the coating in the dry state.

5. 5. The use according to any one of claims 1 to 4, wherein A and / or M is an alkali metal selected from Li, Na, K, Rb and Cs, and A and M are different from each other.

6. 6. The use according to any one of claims 1 to 5, wherein A and / or M is an alkaline earth metal selected from Be, Mg, Ca, Sr and Ba, and A and M are different from each other.

7. 7. The use according to any one of claims 1 to 6, 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 and Ir, and A and M are different from each other.

8. The use according to any one of claims 1 to 7, wherein A and / or M is a poor metal selected from Al, Zn, Ga, In and Sn, and A and M are different from each other.

9. The use according to any one of claims 1 to 8, wherein A and / or M is a metalloid selected from B, Si, Ge and Sb, and A and M are different from each other.

10. 10. The use according to any one of claims 1 to 9, wherein A and / or M is a lanthanide selected from La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu, and A and M are different from each other.

11. The use according to any one of claims 1 to 10, wherein the coating comprises, in the following order from the side of the substrate of the household article to which it is applied, one or more primer coats, optionally one or more continuous or discontinuous decorative coats, and one or more finishing coats.

12. The use according to any one of claims 1 to 11, characterized in that the coating is a fluoropolymer-based coating.

13. 13. Use according to claim 12, wherein the fluoropolymer(s) is / are selected from the group consisting of polytetrafluoroethylene (PTFE), copolymers of tetrafluoroethylene and perfluoropropyl vinyl ether (PFA), copolymers of tetrafluoroethylene and hexafluoropropene (FEP), polyvinylidene fluoride (PVDF), copolymers of tetrafluoroethylene and polymethyl vinyl ether (MVA), terpolymers of tetrafluoroethylene, polymethyl vinyl ether and fluoroalkyl vinyl ether (TFE / PMVE / FAVE) and ethylene tetrafluoroethylene (ETFE), and mixtures thereof.

14. (Bi 1-x A x ) (V 1-y M y ) O 4 The use according to any one of claims 1 to 13, wherein is added into the film of the coating to reduce or prevent color changes of this film.

15. The use according to claim 14, wherein the coating comprises one or more decorations.

16. (Bi 1-x A x ) (V 1-y M y ) O 4 16. Use according to claim 15, wherein is added during decoration to reduce or prevent color changes of said decoration.

17. (Bi 1-x A x ) (V 1-y M y ) O 4 The use according to any one of claims 1 to 13, wherein said compound is added into a film of a coating to reduce or prevent color change of another film of a coating placed on top of said film.

18. (Bi 1-x A x ) (V 1-y M y ) O 4 18. Use according to claim 17, wherein is added to a coating applied under a decoration to reduce or prevent color changes of said decoration.

19. Use according to any one of claims 1 to 18 for reducing or preventing colour changes of said coating during the sintering step of its manufacturing process.

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