EP4162004A1

EP4162004A1 - Glossy outer lacquers

Info

Publication number: EP4162004A1
Application number: EP21737704.3A
Authority: EP
Inventors: Stéphane LEBOEUF; Marie LE BONNEC
Original assignee: SEB SA
Current assignee: SEB SA
Priority date: 2020-06-03
Filing date: 2021-06-03
Publication date: 2023-04-12
Also published as: CN115698203A; FR3111140A1; FR3111140B1; WO2021245360A1

Abstract

The present invention relates to the use of an aqueous phase lacquer formulation comprising at least one alkyd resin, preferably alkyd polyurethane, and at least one additive, characterized in that said formulation does not comprise a water-immiscible co-solvent, for applying a coating to one face of a substrate intended to be heated.

Description

SHINY EXTERIOR LACQUERS

FIELD OF THE INVENTION

The present invention relates to an external coating obtained from an aqueous phase lacquer formulation, said coating being drawable and heat resistant, intended to be applied to a surface capable of being heated. The invention also relates to the process for preparing said coating as well as to a household article comprising at least one layer of such a coating, said article possibly being a cookware, an iron soleplate, iron plates. straighten hair or even the hood of a household appliance.

BACKGROUND OF THE INVENTION

Coatings in the form of at least one layer of lacquer based on resins, generally based on silicone resin, applied to surfaces intended to be heated, in particular to cookware, are known in the field.

Patent FR 2643806 describes, for example, a cooking vessel whose bottom is covered on the outside with a coating based on silicone resin. The coating is obtained from an aqueous formulation comprising a significant portion of xylene solvent. Said silicone resin, however, has the disadvantage of not being very resistant to heat. To overcome these drawbacks, the surface of the cooking vessel has hollows and projections, the silicone resin-based coating being present only in the hollows to prevent deterioration. The coating is therefore not evenly distributed over the surface of the article.

Patent FR 2969636 relates to an external coating of self-crosslinking polyester-silicone lacquer mixed with an aminosilane for an article, in particular culinary, having improved resistance to the dishwasher. The coating is obtained from a formulation of the polyester resin in solvent phase. The examples of the patent show good resistance to dishwasher detergents at a temperature of 55 ° C, but no test of heat resistance during normal use of a cookware intended to be heated is described.

Thus, the lakes commonly used in the field have the main drawback of being in a formulation mixed with often toxic solvents, such as xylene, and emitters of VOCs (volatile organic compound) during their use, having a negative impact on the health of production operators and on the environment. In addition, these resins have low heat resistance, so the coating will scratch and wear off quickly when using hot cookware. The present invention therefore aims to provide a coating obtained from a lacquer formulation devoid of solvent immiscible with water, said coating being resistant to heat, to the dishwasher, being drawable and having an appreciable decorative aspect. , shiny and may be brightly colored.

To this end, the inventors have developed a coating obtained from an aqueous phase lacquer formulation comprising at least one alkyd resin and devoid of co-solvent immiscible with water.

BRIEF DESCRIPTION OF THE INVENTION

A first object of the invention therefore relates to the use of a lacquer formulation in aqueous phase comprising at least one alkyd resin, preferably alkyd polyurethane, and at least one additive, characterized in that said formulation does not include co-solvent immiscible with water, for the application of a coating on a face of a substrate intended to be heated.

A second object of the invention relates to a coating intended to be applied to one side of a substrate intended to be heated, the coating being obtained from the aqueous phase lacquer formulation of the invention.

A third object of the invention relates to the method of applying a coating according to the invention, intended to be applied to one side of a substrate intended to be heated, said method comprising the following steps:

(i) Preparation of an aqueous phase lacquer formulation as defined in the invention;

(ii) application to said face of the substrate of a layer of said lacquer formulation obtained at the end of step (i);

(v) Baking the surface of the substrate coated with at least one layer of lacquer.

A fourth object relates to a household article, preferably culinary, at least one side of which is coated with the coating according to the invention.

DETAILED DESCRIPTION OF THE INVENTION The aqueous phase lacquer formulation

The term “lacquer formulation in aqueous phase” in the context of the present invention denotes a liquid composition comprising water and at least one so-called alkyd resin. Said formulation is characterized in that it is devoid of co-solvent immiscible with water. The term “co-solvent immiscible” with water is understood to mean a solvent which forms a heterogeneous mixture in the presence of water. In the context of the present invention, this term designates in particular solvents that are toxic, volatile and / or emitting VOCs (volatile organic compounds) at room temperature or at the temperatures used during the process for preparing the coating of the invention. In particular, “water-immiscible co-solvents” include hydrocarbons, in particular ethylenic and aromatic hydrocarbons, aldehydes, their derivatives and their combinations. Ethylenic and aromatic hydrocarbons denote, for example, xylene, toluene, benzene, naphthalene, their derivatives and their combinations.

The formulation is said to be free of such a co-solvent if it does not include it or if it contains less than 1% by weight relative to the total weight of the formulation.

Preferably, the lacquer formulation used in the invention does not comprise or comprises less than 1% by weight relative to the weight of the formulation, of solvents chosen from dimethylformamide (DMF), ethers, in particular tetrahydrofuran (THF) , acetonitrile, ketones, their derivatives and their combinations. In a preferred embodiment, the lacquer formulation does not include these solvents.

The water content of said lacquer formulation is typically between 30 and 80% relative to the total weight of the formulation, preferably between 40 and 70%, more preferably between 45 and 55%.

Alkyd resin

The lacquer formulation used in the present invention comprises at least one so-called alkyd resin. The term "alkyd resin" denotes a particular family of polyester polymers which result from the polycondensation of polyols, polycarboxylic acids and fatty acids. These resins are commonly used in the field of paints and can be prepared according to methods known to those skilled in the art. In particular, one skilled in the art is able to select the polyols, polycarboxylic acids and fatty acids suitable for the preparation of the alkyd resins of the invention.

For example, said fatty acids include fatty acids with long unsaturated chains such as oleic, linoleic, linolenic acid, tall oil, vegetable oils including for example soybean oil, olive oil, rapeseed oil, sunflower oil, safflower oil, corn oil, cottonseed oil, palm oil, sesame oil, Jatropha oil, castor oil, grape seed oil, peanut oil, and mixtures thereof. Polyols denote compounds comprising two or more hydroxyl groups. In the context of the invention, they are for example chosen from trimethylpentanediol, diethylene glycol, neopentylglycerol, glycerol, pentaerythritol, trimethylolethane, trimethylolpropane, their derivatives and their mixtures.

Polycarboxylic acids denote compounds comprising two or more carboxylic acid functions. They include in particular anhydrides. In the context of the invention, the polycarboxylic acids are in particular aromatic and are, for example, chosen from phthalic anhydride, isophthalic acid, tetrahydrophthalic acid or anhydride, and mixtures thereof.

Preferably, the alkyd resins used in the present invention are alkyd polyurethane resins. These resins are modified by incorporation of urethane functions of formula -NH-C (O) -O- into the polymer. They are obtained by adding an isocyanate derivative during the preparation of the resin. Said isocyanate derivative is for example chosen from toluene isocyanate (TDI) or diphenylmethane diisocyanate (MDI).

In a particular embodiment, the alkyd or polyurethane alkyd resins used in the present invention are modified by adding silicone.

The alkyd resins used in the lacquer formulation of the invention have a molecular weight typically between 1500 and 5000 g / mol.

The alkyd resins used in the lacquer formulation of the invention advantageously have an acid value of between 10 and 30, preferably between 15 and 25.

The alkyd or derivative resins used in the present invention are in particular in the form of an aqueous emulsion, in particular devoid of volatile organic compounds.

Alkyd resins are typically thermosetting, that is, they solidify under the effect of temperature. The alkyd resins used in the invention can solidify at room temperature, typically at a temperature between 20 ° C and 40 ° C.

The lacquer formulation used in the invention comprises an alkyd resin as described above or a mixture of alkyd resins. Preferably, the lacquer formulation comprises a single polyurethane alkyd resin.

The polyurethane alkyd resin used in the lacquer formulation of the invention is, for example, chosen from the commercial resins WorléeSol® E 330W and WorléeSol® VPE 320 W.

The lacquer formulation according to the invention typically comprises a proportion of alkyd resin which varies from 20% to 50% by weight relative to the total weight of the formulation, preferably from 25% to 40% by weight.

Additives The lacquer formulation used in the invention further comprises at least one additive chosen from the group consisting of anti-foaming agents, spreading agents, antibacterial agents, wetting agents, thickeners, co-solvents, pigments, flakes and flake orienters.

The anti-foaming agents, spreading agents, antibacterial agents, wetting agents, thickeners, pigments, flakes and flake orienters used are well known to those skilled in the art. When one of these additives is present in the formulation, it is advantageously added in an amount which varies from 0.1% to 8% by weight relative to the total weight of the formulation, preferably from 0.4% to 6% . The lacquer formulation used in the invention can comprise a co-solvent, advantageously chosen from glycols and alcohols. This co-solvent makes it possible to optimize the application of the coating by preventing it from drying too quickly. For example, the lacquer formulation can comprise ethanol, propanol, monopropylene glycol, ethylene glycol or mixtures thereof, preferably monopropylene glycol or ethylene glycol, more preferably monopropylene glycol. In this embodiment, the amount of co-solvent in the formulation typically varies from 1% to 10% by weight relative to the total weight of the formulation, preferably from 2% to 8%.

In a preferred embodiment, the lacquer formulation comprises at least two additives, preferably chosen from a co-solvent, flakes and pigments. According to a particular embodiment, the formulation of lacquer in aqueous phase does not include any co-solvent. In other words, said formulation does not include any solvent other than water.

The coating

The present invention also relates to a coating intended to be applied to one side of a substrate intended to be heated, said coating being obtained from the formulation of lacquer in aqueous phase as defined above.

The coating according to the present invention is in the form of at least one lacquer film resulting from the lacquer formulation as defined above, distributed uniformly over the surface. Said lacquer film therefore comprises at least one alkyd resin, preferably alkyd polyurethane, and at least one additive.

The coating according to the present invention therefore consists of one or more lacquer films as defined above, applied one on top of the other, so that the coating typically has a thickness which varies from 1 µm to 100 µm, from preferably from 10 μm to 80 μm and more preferably from 20 μm to 50 μm. Typically, the coating comprises three layers of lacquer. According to one embodiment, the coating consists of several lacquer films, at least one of the films of which is distributed uniformly over the entire surface. Advantageously, all of the lacquer films are distributed uniformly.

The term "uniformly" means that the lacquer film forms a layer completely covering the surface and having the same thickness and appearance over the entire surface.

According to another embodiment, the coating consists of several lacquer films, at least one of which is distributed evenly over the surface and at least one other film is distributed non-uniformly, so that it can create a decorative pattern for example.

The final coating obtained by the preparation process according to the invention as described below comprises an alkyd resin, preferably a polyurethane alkyd resin as defined above, and an additive chosen from flakes and pigments.

Defoamers, spreading agents, wetting agents, thickeners and co-solvents provide a lacquer formulation with the optimum viscosity properties for the easiest possible application. These agents are not present in the final coating. This is because they do not withstand the baking step during the preparation of the coating of the invention as described below. Antifoam agents and spreading agents are especially present in the formulation when the coating is applied by screen printing.

The flakes and pigments have a decorative role and are present in the final coating according to the invention.

The coating is applied to one side of a substrate intended to be heated, the side of the substrate advantageously being made of glass, ceramic or metal, preferably metal. When it is made of metal, the face of the substrate is for example aluminum, titanium, copper, steel or one of their alloys, preferably aluminum. According to a preferred embodiment, the coating of the invention is applied to one side of a cookware, an iron soleplate, the plates of a hair straightener, a baking plate or a cover of an iron. household appliance, preferably a cookware. Thus, advantageously, the coating is applied to the exterior face of a cookware, said exterior face being intended to be placed on a heat source.

The coating according to the invention has sufficient adhesion and flexibility to withstand heat, dishwasher and surface shaping operations such as stamping and fluorotinning. In other words, the coating will not scratch, crack or peel off when surface is heated, washed in the dishwasher or shaped.

Furthermore, the coating according to the invention is preferably bright and shiny in color. This brightness is measured in particular using a colorimetry device (glossmeter) and is between 80 and 100 UB at 60 °. The color and gloss of the coating is not deteriorated by heat, the dishwasher or any shaping operation. In particular, the coating does not brown in the heat.

Coating application process

The present invention also relates to a method of applying a coating according to the invention as defined above, intended to be applied to one side of a substrate intended to be heated, said method comprising the following steps:

(i) Preparation of an aqueous phase lacquer formulation as defined above;

(v) Baking the surface of the substrate coated with at least one layer of lacquer. Step (ii) can be carried out by spraying, screen printing or by roller. Spray application means the formulation is projected in fine droplets onto the surface. The spray formulation is sprayed onto the surface so as to cover all or part of it. Each lacquer layer obtained by spray application typically has a thickness which ranges from 1 µm to 40 µm, preferably 3 µm to 30 µm.

The screen printing application involves passing the coating through a screen of fabric using a doctor blade. Each layer of lacquer obtained via the application by screen printing typically has a thickness which varies from 1 µm to 20 µm, preferably from 1 µm to 10 µm.

Roller application involves passing the coating through a metering roller and an inking roller. Each lacquer layer obtained by roller application typically has a thickness which ranges from 1 µm to 20 µm, preferably 1 µm to 10 µm.

A drying step (iii) of said lacquer formulation layer applied in step (ii) follows step (ii) when the coating is applied by screen printing or by roller. Optionally, this drying step (iii) can also be carried out following step (ii) when the application is carried out by spraying. The drying step makes it possible to limit, or even eliminate, the generation of defects, such as bubbles or cracks, in the coating during the curing step (v). A cooling step (iv) of the face of the substrate coated with a layer of lacquer resulting from step (iii) follows step (iii) when the coating is applied by screen printing. Optionally, this cooling step can also be carried out after step (iii) when the application is done by roller or by spraying. Advantageously, the cooling step makes it possible to avoid too rapid drying of the new layer and a powdering phenomenon (the dried liquid product is in the form of powder).

Step (ii) can be repeated several times for spray application. Optionally, the sequence of steps (ii) and (iii), or (ii), (iii) and (iv) can be repeated several times when the application is by spraying.

The sequence of steps (ii) and (iii) or optionally the sequence of steps (ii), (iii) and (iv) can be repeated several times in case of application by roller.

The sequence of steps (ii), (iii) and (iv) can be repeated several times in case of application by screen printing.

The substrate can be shaped before or after the coating application process.

Preferably, all of the steps (i) to (v) are carried out during the implementation of the method of the invention.

Advantageously, the sequence of steps (ii), (iii) and (iv) is repeated several times so as to obtain a coating comprising several layers of lacquer and having a total thickness which varies from 1 μm to 100 μm, preferably 10 μm. pm to 80 pm and more preferably from 20 pm to 50 pm.

Advantageously, the sequence of steps (ii), (iii) and (iv) is repeated twice so as to obtain a coating comprising three layers of lacquer and having a total thickness which varies from 1 μm to 100 μm, preferably from 10 μm. pm to 80 pm and more preferably from 20 pm to 50 pm.

In a preferred embodiment, the pH of the lacquer formulation is adjusted before application to a pH of between 8 and 12, preferably between 9 and 10, when the application (ii) is done by screen printing or by rollers. . The pH of the formulation is advantageously adjusted to the values described when a straw orientator is used.

The method according to the invention optionally comprises a preliminary step of pretreating the face of the substrate on which the coating is intended to be applied, carried out before step (i). This step is carried out by means well known to those skilled in the art in order to make the face of the substrate more suitable for fixing the coating according to the invention. For example, the face of the substrate can be treated with abrasive means, such as brushing to make it rougher so as to improve the adhesion of the coating.

According to a particular embodiment, the method of applying a coating according to the invention on one face of a substrate intended to be heated corresponds to the preparation process A comprising the following steps:

(i) Preparation of an aqueous phase lacquer formulation as defined above;

(i ’) Shaping the substrate;

(ii) application by spraying on said face of the substrate of a layer of said lacquer formulation obtained at the end of step (i);

(v) Baking the surface of the substrate coated with at least one layer of lacquer; step (ii) optionally being repeated several times, preferably twice.

Optionally, method A further comprises step (iii) and optionally step (iv), carried out following step (ii). In this embodiment, the sequence of steps (ii) and (iii), or (ii), (iii) and (iv) can therefore optionally be repeated several times.

Advantageously, all the steps of method A are carried out. According to a particular embodiment, the method of applying a coating according to the invention intended to be applied to one side of a substrate intended to be heated corresponds to the preparation process B comprising the following steps:

(i) Preparation of an aqueous phase lacquer formulation as defined above;

(ii) Application by screen printing on said face of the substrate of a layer of said lacquer formulation obtained at the end of step (i);

(iii) drying of said lacquer formulation layer applied in step (ii),

(iv) Cooling of the surface of the substrate coated with a layer of lacquer resulting from step (iii),

(v) Baking the surface of the substrate coated with at least one layer of lacquer from step (iv);

(vi) Shaping of said substrate, one face of which is coated with at least one layer of lacquer resulting from step (v), the sequence of steps (ii), (iii) and (iv) being optionally repeated several times , preferably twice.

Advantageously, all of the steps (i) to (vi) of method B are carried out.

According to a particular embodiment, the method of applying a coating according to the invention intended to be applied to a face of a substrate intended to be heated corresponds to the preparation process C comprising the following steps: (i) Preparation of an aqueous phase lacquer formulation as defined above;

(ii) Application by roller on said surface of a layer of said lacquer formulation obtained at the end of step (i);

(iii) drying of said lacquer formulation layer applied in step (ii),

(v) Baking the surface of the substrate coated with at least one layer of lacquer;

(vi) Shaping of said substrate, one face of which is coated with at least one layer of lacquer resulting from step (v), the sequence of steps (ii) and (iii) being optionally repeated several times, preferably two time.

Optionally, method C further comprises step (iv), carried out following step (iii). In this embodiment, the sequence of steps (ii), (iii) and

(iv) can therefore optionally be repeated several times.

Advantageously, all the steps of method C are carried out.

Whatever the method of application, the drying step, when carried out, is advantageously carried out at a temperature which varies from 30 ° C to 100 ° C, preferably at a temperature of 80 ° C, for a period of time. time which varies from 30 minutes to 2 hours, preferably for 1 hour.

Whatever the method of application, the cooling step, when it is carried out, is advantageously carried out at a temperature below 40 ° C, preferably at a temperature between 15 and 35 ° C.

Whatever the method of application, the baking step is preferably carried out at a temperature which varies from 200 ° C to 300 ° C, preferably at 280 ° C, for a time between 1 min and 30 min , preferably between 3 min and 20 min.

Once the surface is coated, it can optionally be shaped, for example by stamping or by fluorotouring, in order to give it the shape of the desired article. This shaping step does not damage the coating which has sufficient adhesion and flexibility to undergo this operation.

The method of the invention can also be carried out on the surface of an article which already has its final shape.

The process for preparing a coating according to the invention is preferably carried out on a surface made of glass, ceramic or metal, preferably metal. When it is made of metal, the surface is made of aluminum, titanium, copper, steel or one of their alloys, preferably aluminum. According to a preferred embodiment, this surface is that of a cookware, of an iron soleplate, of plates of a straightening iron, of a cooking plate or of a cover of a household appliance, preferably of a cookware.

The household item

A final object of the present invention consists of a household article, preferably culinary, at least one face of which is coated with the coating as described above. The term "household item" should be understood to mean cookware and household appliances.

The household appliances referred to here are intended to produce heat.

By the expression "cookware", it should be understood within the meaning of the present invention an object intended for cooking. To do this, it is intended to receive heat treatment.

By the expression “object intended to receive a heat treatment”, it should be understood within the meaning of the present invention an object which will be heated by an external heating system such as stoves, saucepans, sauté pans, woks, grills. barbecues 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.

By the expression “object intended to produce heat”, it should be understood within the meaning of the present invention a heating object having its own heating system such as irons, hair straighteners, steam generators, kettles. or electrical appliances intended for cooking.

The present invention relates in particular to a household article directly obtained or capable of being obtained by the application method according to the invention as described above.

In particular, the culinary article comprising the coating according to the invention corresponds to a frying pan, a saucepan, a wok, a Dutch oven, a sauté pan or a crepe maker.

The invention is described more precisely by means of the following examples, without being limited thereto.

EXAMPLES

A) Spray application

The following lacquer 1 formulation was carried out:

[Table 1]

WorléeSol® E 330W resin is in the form of an aqueous emulsion of polyurethane alkyd resin with a resin content of 42% by weight relative to the total weight of the emulsion.

The following formulation of lacquer 2 was carried out: [Table 2]

WorléeSol® VPE 320 resin is in the form of an aqueous emulsion of polyurethane alkyd resin with a resin content of 40% by weight relative to the total weight of the emulsion.

Formulations 1 and 2 were each applied to the outer surface of a pre-shaped brushed aluminum pan. The application is by spraying using a compressed air nozzle gun type Devilbiss SRI HD Finishing_Brands BH11 9LH UK. We apply a layer.

After application of the formulation, a baking step at 280 ° C. for 15 min is performed.

B) Application by screen printing

The following lacquer formulation 3 was carried out:

[Table 3]

^* The buffer allows the pH of the formulation to be adjusted to 9.22

The following formulation of lacquer 4 was carried out: [Table 4] * The buffer allows the pH of the formulation to be adjusted to 9.22

Formulations 3 and 4 were each applied to a brushed aluminum surface. The application is done by screen printing with a screen of 54 Mesh. We apply 3 coats. Between each coat, the coating is dried at about 80 ° C and then cooled to about 35 ° C.

After application of the formulation, a baking step at 280 ° C. for 15 min. is done.

The surface is then shaped by stamping. Results:

The gloss of the coatings is measured according to the method: number of UB at 60 °

The final coating resulting from formulation 1 has a thickness of 51 ± 6 μm on the bottom and 65 ± 2 μm on the skirt. The brightness is 89 ± 1 BU. The final coating resulting from formulation 2 has a thickness of 38 ± 2 μm on the bottom and 53 ± 5 μm on the skirt. The gloss is 99 ± 6 BU.

The final coating resulting from formulation 3 has a thickness of 22 ± 2 µm and a gloss of 57 ± 3 BU.

The final coating resulting from formulation 4 has a thickness of 31 ± 3 µm and a gloss of 89.5 ± 0.8 BU.

The coatings are deformable, can be drawn, they are flame resistant (20 minutes empty on a cooking fire) and 50 cycles in the dishwasher.

Claims

1. Use of a lacquer formulation in aqueous phase comprising at least one alkyd resin, preferably alkyd polyurethane, and at least one additive, characterized in that said formulation does not comprise a co-solvent immiscible with water , for the application of a coating on a face of a substrate intended to be heated.

2. Use according to claim 1, characterized in that the water content of said lacquer formulation is between 30 and 80% relative to the total weight of the formulation, preferably between 40 and 70%, more preferably between 45 and 55%.

3. Use according to claim 1 or 2, characterized in that said additive included in said lacquer formulation is chosen from the group consisting of anti-foam agents, spreading agents, antibacterial agents, wetting agents, thickeners. , co-solvents, pigments, flakes and flake orienters.

4. Use according to any one of claims 1 to 3, characterized in that said lacquer formulation comprises at least two additives, preferably selected from the group consisting of flakes, pigments and co-solvents.

5. Use according to claim 3 or 4, characterized in that the co-solvents are chosen from the group consisting of glycols, such as monopropylene glycol or ethylene glycol.

6. Use according to any one of claims 1 to 5, characterized in that said coating is applied in the form of at least one lacquer film, preferably by spraying, by screen printing or by roller of said lacquer formulation, on one side of the substrate intended to be heated.

7. Use according to any one of claims 1 to 6, characterized in that the face of the substrate intended to be heated is made of glass, ceramic or metal such as aluminum, titanium, copper or steel. , preferably metal.

8. Use according to any one of claims 1 to 7, characterized in that the coating is applied to one side of a culinary article, an iron soleplate, plates of a straightening iron, a plate of cooking or a cover of a household appliance, preferably a cookware.

9. Use according to claim 8, characterized in that the coating is applied to the outer face of a cookware, said outer face being intended to be placed on a heat source.

10. Coating intended to be applied to one side of a substrate intended to be heated, the coating being obtained from the aqueous phase lacquer formulation as defined in claims 1 to 5.

11. Coating according to claim 10, in the form of at least one lacquer film comprising at least one alkyd resin, preferably alkyd polyurethane, and at least one additive, characterized in that at least one lacquer film of the coating is distributed evenly over the substrate.

12. Coating according to claim 11, characterized in that said additive is chosen from the group consisting of pigments and flakes.

13. Coating according to one of claims 10 to 12, characterized in that the coating has a thickness between 1 pm and 100 pm, preferably between 10 pm and 80 pm and more preferably between 20 pm and 50 pm.

14. Coating according to any one of claims 10 to 13, characterized in that the face of the substrate is made of glass, ceramic or metal such as aluminum, titanium, copper, steel or one of theirs. alloys.

15. Coating according to any one of claims 10 to 14, characterized in that it is applied to the face of a culinary article, an iron soleplate, the plates of a straightening iron, a plate of cooking or a cover of a household appliance, preferably the face of a cookware.

16. A method of applying a coating as defined in claims 10 to 15, intended to be applied to one side of a substrate intended to be heated, said method comprising the following steps:

(i) Preparation of an aqueous phase lacquer formulation as defined in claims 1 to 5;

(v) Baking the face of the substrate coated with at least one layer of lacquer.

17. The method of claim 16, characterized in that the application is by screen printing, by roller or by spraying.

18 The method of claim 17, characterized in that the application is by screen printing or by roller, the method further comprising step (iii) following after step (ii):

(iii) Drying the lacquer formulation layer applied in step (ii).

19. The method of claim 18, characterized in that the application is by screen printing, the method further comprising step (iv) following after step

(iii):

(iv) Cooling the surface of the substrate coated with a layer of lacquer resulting from step (iii).

20. The method of claim 19, characterized in that the sequence of steps

(ii), (iii) and (iv) is repeated several times, preferably twice.

21. A method according to any one of claims 16 to 20, wherein a substrate shaping step is performed before step (ii) or after step (v).

22. A method according to any one of claims 16 to 21, wherein the coating is applied to one side of a cookware, an iron soleplate, plates of a hair straightener, a baking sheet or a cover of a household appliance, preferably the face of a cookware.

23. Household article, preferably culinary, at least one side of which is coated with a coating as defined in claims 10 to 15.