Cooking element coated with a textured polymeric film

Abstract

The invention relates to a coated cooking element (1) for a cooking utensil or an electrical cooking appliance comprising a metal substrate (2) coated on at least one face (2a) by a film (3) forming a cooking face (4), the film (3) comprising a layer (3a) arranged on the side opposite the cooking face (4), the layer (3a) comprising one or more semi-crystalline or amorphous thermoplastic polymers, the film (3) being assembled with the metal substrate (2), the layer (3a) being in contact with the face (2a) of the metal substrate (2), and such that the cooking face (4) has a structure (5) that constitutes a protrusion characterised by a maximum profile height Rt, measured according to standard DIN 4768 E of 1 January 1990, of between 10 and 500 µm, preferably between 20 and 100 µm. The invention also relates to a method for manufacturing a coated cooking element, wherein the cooking face (4) has a structure (5), and to a cooking utensil or an electrical cooking appliance comprising the coated cooking element (1).

Description

[0001] COOKING ELEMENT COATED WITH A TEXTURED POLYMER FILM

[0002] FIELD OF THE INVENTION

[0003] The present invention relates to the field of cooking elements coated with a non-stick film having a surface structure, as well as methods for obtaining such cooking elements.

[0004] It also concerns cookware and electrical cooking appliances comprising such cooking elements.

[0005] STATE OF THE ART

[0006] In the cookware industry with a non-stick cooking surface, the performance of non-stick coatings and the development of processes for obtaining such coatings are important concerns.

[0007] Conventionally, a metal substrate is first shaped to form a cookware, and then the inner surface of the cookware is coated with a fluororesin having excellent heat resistance such as polytetrafluoroethylene (PTFE) using a liquid spray coating process or a powder coating process. Alternatively, the coated substrate is coated and then shaped.

[0008] The liquid spray coating process has several disadvantages. When the metal substrate has a curved shape, it is difficult to achieve a uniform coating thickness. The liquid spray coating process also involves the use of solvents or volatile organic compounds that evaporate during the process and must be recovered and recycled. From an environmental perspective, a solvent-free and volatile organic compound-free process is preferred. Furthermore, the coating thickness is limited. Cracking is likely to occur when the coating thickness is too thick.

[0009] The powder coating process also has disadvantages. The resulting coating has pinhead-like defects that can lead to a reduction in non-stick properties. Coatings obtained using both processes can have significant surface roughness that can cause cleaning problems, as some cooking residue can persist on the surface of the coating even after several washes. In addition, the metal substrate on which the coating is deposited also usually has significant roughness, to facilitate the adhesion of the coating. Thus, scratches affecting the coating in the protruding areas of the cooking surface can reveal the metal substrate, which corresponds to a significant degradation of the coating.

[0010] In order to overcome the above-mentioned drawbacks, the state of the art describes metal substrates coated with fluorinated films by rolling.

[0011] Patent application KR20150030719 describes a kitchen utensil comprising a body including a metal substrate on which a film of a fluororesin is laminated. A method for obtaining a kitchen utensil is also described. In Example 1, a PTFE multilayer film is used without information on the nature of the layers.

[0012] Application KR20160099388 describes the process for obtaining a metal substrate coated with a fluorinated film (devoid of a primer layer comprising an organic compound or an adhesive). The fluorinated film is a multilayer film obtained by successive deposition on a support of an aqueous dispersion of the constituents of the layer (fluorinated resin and possibly an inorganic filler) which is dried and sintered. The multilayer film is then removed from its support and positioned on the metal substrate before assembly. The layer of the fluorinated film in contact with the metal is made of PTFE and a resin chosen from FEP, PFA, TFM, MFA (or their mixture) which has good flow properties, thus allowing good adhesion, which PTFE does not allow. The metal substrate / fluorinated film assembly is carried out by thermal compression, in a static press or between rollers (roll-to-roll process).

[0013] Non-stick cooking surfaces obtained from polymer films allow for products with a high coating thickness, guaranteeing increased durability of the non-stick coating.

[0014] These surfaces also have an extremely smooth surface with few defects, reinforcing their non-stick character. However, since the surface of such cooking utensils is very smooth, particularly visible defects can appear over time. Indeed, polymer materials have relatively weak mechanical characteristics, particularly when hot, the use of utensils such as spatulas can generate scratches degrading the visual appearance of the surface. These scratches, even if they are shallow, are all the more visible when the cooking surface is smooth.

[0015] In addition, the very smooth surface of such cookware contributes to the easy spread of scratches. In addition, since the surface of such cookware is very smooth and shiny, possible surface defects of the polymer film or defects occurring during the manufacture of the cookware are particularly visible, which detracts from the aesthetic appearance of the cookware.

[0016] STATEMENT OF THE INVENTION

[0017] From an industrial point of view, there remains a need to develop cooking elements comprising a metal substrate coated with a polymeric film forming a cooking surface, which makes it possible to delay the appearance of visible defects on the cooking surface, such as scratches, and to limit the visualization of defects in the appearance of the cooking surface.

[0018] The applicant has thus developed a cooking element comprising a metal substrate coated with a polymeric film whose surface is textured, which makes it possible to limit the visualization of appearance defects and defects appearing during the life of the cooking element while making it possible to maintain non-stick performance over a long period. The characteristics of the cooking element according to the invention make it easier to use metal utensils for stirring food and to more easily envisage cooking hard foods such as shellfish.

[0019] The applicant has also developed a method for obtaining such a cooking element comprising a step of creating on the cooking face of the cooking element a structure constituting a relief. Summary of the invention

[0020] The inventors have discovered that by generating a structuring constituting a relief on the cooking face (4) of a cooking element (1) comprising a metal substrate (2) and a film (3) assembled, it is possible to limit the visualization of appearance defects and defects such as scratches which may appear over time.

[0021] A first subject of the invention thus relates to a coated cooking element (1) for a culinary article or electrical cooking appliance, comprising a metal substrate (2) coated on at least one face (2a) with a film (3) forming a cooking face (4), said film (3) comprising a layer (3a) arranged on the side opposite the cooking face (4), said layer (3a) comprising one or more semi-crystalline or amorphous thermoplastic polymers, said film (3) being assembled with said metal substrate (2), said layer (3a) being in contact with the face (2a) of the metal substrate (2), and such that said cooking face (4) has a structuring (5) constituting a relief characterized by a maximum profile height R t measured according to standard DI N 4768 E of January 1, 1990 between 10 and 500 pm, preferably between 20 and 100 pm.

[0022] The invention also relates to a method for manufacturing a coated cooking element (1) for a culinary article or electrical cooking appliance comprising a cooking face (4) having a structure (5) constituting a relief characterized by maximum profile height R tmeasured according to standard DI N 4768 E of January 1, 1990 between 10 and 500 pm, preferably between 20 and 100 pm, said method comprising the following successive steps i. to v.: i. Providing a metal substrate (2), ii. Optionally, prior treatment of the face (2a) of said metal substrate (2) intended to be coated, iii. Providing a film (3) forming a cooking face (4) comprising a layer (3a) comprising one or more semi-crystalline or amorphous thermoplastic polymers, iv. Positioning the layer (3a) of the film (3) so that the layer (3a) is opposite said face (2a) of the metal substrate (2), v. Carrying out the assembly of said metal substrate (2) and said film (3) by hot pressing, said method further comprising a step vi. of creating said structuring (5), said steps v. and vi. being able to be simultaneous or successive.

[0023] The invention also relates to a culinary article (100) comprising a coated cooking element (1) according to the invention or obtained according to the method of the invention, as well as an electrical cooking appliance (200) comprising a coated cooking element (1) and a heating source (210) configured to heat said coated cooking element (1), characterized in that said coated cooking element (1) is in accordance with the invention or is obtained according to the method of the invention.

[0024] Other aspects of the invention are as described below and in the claims.

[0025] Definitions

[0026] The term "film" is understood to mean, within the meaning of the present invention, an assembly consisting of one or more superimposed layers intended to be assembled with the metal substrate. The term "film" also corresponds to said assembly once assembled with the metal substrate.

[0027] The term "layer" is understood to mean, within the meaning of the present invention, a continuous layer. A continuous layer (or also called a monolithic layer) is a single whole forming a total flat area completely covering the surface on which it is placed or is going to be placed.

[0028] For the purposes of the present invention, "hot pressing" means the method of assembling the previously heated metal substrate (2) and the film (3) between a lower tool and an upper tool.

[0029] For the purposes of the present invention, the term "aluminum alloy" means an aluminum alloy of series 1000, 2000, 3000, 4000, 5000, 6000, 7000 and 8000.

[0030] By "maximum profile height R tmeasured according to the standard DI N 4768 E of January 1, 1990" means the distance between the line of projections corresponding to the highest height and the line of hollows corresponding to the highest depth in the measurement interval (reference section) of a profile filtered according to the standard DIN 4768 E of January 1, 1990. The surface topography can be studied in particular with a profilometer with a probe equipped with a fine stylus equipped with a diamond tip, or with an optical metrology device type Àltisurf®, in which a chromatic confocal sensor allows a contactless measurement.

[0031] The expression "cooking article" is understood to mean, within the meaning of the present invention, an object intended for cooking. To do this, it is intended to be heated to cook or reheat the food carried by the cooking element or contained in the cooking element.

[0032] By the expression "object intended to be heated to cook or reheat the food carried by the cooking element or contained in the cooking element", it is necessary to understand within the meaning of the present invention an object which will be heated by an external heating system such as a cooking zone, such an object being able in particular to be a frying pan, a saucepan, a sauté pan, a wok, a barbecue grill, and which is capable of transmitting the heat energy provided by this external heating system to a material or food in contact with said object.

[0033] The expression "electric cooking appliance" is understood to mean, within the meaning of the present invention, an object intended for cooking. To do this, it is configured to produce heat.

[0034] The expression "object configured to produce heat" is understood to mean, within the meaning of the present invention, a heating object having its own heating system.

[0035] DESCRIPTION OF FIGURES

[0036] [Fig. 1] represents a sectional view of an exemplary embodiment of a coated cooking element (1), comprising a film (3) and a metal substrate (2), before assembly according to the method of the invention.

[0037] [Fig. 2] represents a sectional view of an exemplary embodiment of a coated cooking element (1) according to the method of the invention, comprising a film (3) and a metal substrate (2).

[0038] [Fig.3] represents a schematic sectional view of a coated cooking element (1) comprising a metal substrate (2) coated with a film (3) forming a cooking face (4), said cooking face (4) having a periodic structuring (5) of steps Àr. [Fig.4] represents a sectional view of an exemplary embodiment of a coated cooking element (1), comprising a film (3) and a metal substrate (2), before assembly according to the method of the invention, said method comprising the step of assembling said film (3) and said metal substrate (2) by pressing between the lower tool (12À) and the upper tool (12B) of a press such that the plane of the upper tool (12B) coming into contact with the cooking face (4) has a texturing (6).

[0039] [Fig.5] represents a sectional view of an exemplary embodiment of a coated cooking element (1), comprising a film (3) and a metal substrate (2), before assembly according to the method of the invention, said method comprising the step of assembling said film (3) and said metal substrate (2) by pressing between the lower tool (12A) and the upper tool (12B) of a press, a textured spacer (7) being positioned opposite the cooking face (4) during assembly.

[0040] [Fig. 6] illustrates a coated cooking element (1) according to the invention forming a cooking container.

[0041] [Fig. 7] illustrates a culinary article (100) comprising a coated cooking element (1) according to Figure 6.

[0042] [Fig. 8] illustrates an electrical cooking appliance (200) comprising a coated cooking element (1) according to Figure 6.

[0043] DETAILED DESCRIPTION OF THE INVENTION

[0044] The inventors have developed a coated cooking element (1) for a cooking article or electrical cooking appliance meeting the expressed needs as well as a method for obtaining such a coated cooking element (1).

[0045] Cooking element

[0046] The invention thus relates to a coated cooking element (1) for a culinary article or electrical cooking appliance, comprising a metal substrate (2) coated on at least one face (2a) with a film (3) forming a cooking face (4), said film (3) comprising a layer (3a) arranged on the side opposite the cooking face (4), said layer (3a) comprising one or more semi-crystalline or amorphous thermoplastic polymers, said film (3) being assembled with said metal substrate (2), said layer (3a) being in contact with the face (2a) of the metal substrate (2), and such that said cooking face (4) has a structuring (5) constituting a relief characterized by a maximum profile height R t measured according to standard DI N 4768 E of January 1, 1990 between 10 and 500 pm, preferably between 20 and 100 pm.

[0047] Metal substrate (2)

[0048] As metallic substrates (2) which can be used in the context of the invention, mention may advantageously be made of substrates made of aluminum, stainless steel, cast iron or aluminum, or titanium or copper.

[0049] For the purposes of the present invention, aluminum means a metal consisting of 100% aluminum or an aluminum alloy.

[0050] Advantageously, the metal substrate (2) is an aluminum substrate, a stainless steel substrate or a multi-layer metal substrate, in particular two-layer, three-layer or four-layer, these multi-layers being able to be obtained for example by co-rolling, by hot diffusion under load (solid state bonding) or by hot or cold impact bonding.

[0051] Preferably, the metal substrate (2) comprises alternating layers of metal and / or metal alloy.

[0052] According to one embodiment, the metal substrate (2) is an aluminum alloy substrate, a stainless steel substrate or a multi-layer metal substrate whose face (2a) is made of aluminum alloy or stainless steel.

[0053] Preferably, the metal substrate (2) is an aluminum substrate.

[0054] Advantageously, the thickness of the metal substrate (2) is between 0.5 mm and 10 mm.

[0055] Advantageously, the face (2a) of the metal substrate (2) has undergone a surface treatment prior to assembly with the film (3) making it possible to improve the adhesion of said film to said substrate. According to one embodiment, the surface of the face (2a) of the metal substrate (2) has undergone a surface treatment, said surface treatment being a chemical attack, brushing, hydration, sandblasting, shot blasting, a physicochemical treatment of the plasma or corona or laser type, a chemical activation or a combination of these different techniques.

[0056] Advantageously, the average arithmetic roughness Ra of the surface of the face (2a) of the metal substrate (2) is greater than or equal to 1 pm.

[0057] The arithmetic mean roughness Ra is measured using a roughness meter according to ISO 4287. Ra represents the arithmetic mean of the deviations from the mean. The surface topography can be studied in particular with a profilometer with a probe equipped with a fine stylus equipped with a diamond tip, or with an optical metrology device such as Altisurf®, in which a chromatic confocal sensor allows a contactless measurement. The study of this surface topography makes it possible to define the arithmetic mean roughness Ra.

[0058] Advantageously, the cooking element (1) does not comprise an intermediate layer of a metal oxide between the metal substrate (2) and the film (3) described below.

[0059] Movie (3)

[0060] The film (3) comprises a layer (3a) comprising one or more semi-crystalline or amorphous polymers, said layer (3a) being intended to be brought into contact with said face (2a) of said metal substrate (2).

[0061] According to one embodiment, the semi-crystalline or amorphous thermoplastic polymer(s) of the layer (3a) are chosen from: 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, polyarylether ketones (PAEK), including polyether ketone (PEK), polyether ether ketone (PEEK), polyether ketone ketone (PEKK), polyether ether ketone ketone (PEEKK), polyether ketone ether ketone ketone (PEKEKK), preferably polyether ether ketone (PEEK), polyamideimide (PAI), polyimide (PI), polyetherimide (PEI), polybenzymidazole (PBI) and mixtures thereof.

[0062] The melting point of PTFE and semi-crystalline thermoplastic polymers and the glass transition temperature (Tg) of amorphous thermoplastic polymers can be determined by thermal analysis methods such as Differential Thermal Analysis (DSC) or Dynamic Mechanical Analysis (DMA).

[0063] The film (3) may consist of a single layer (3a) also forming a cooking face (4).

[0064] According to another configuration, the film (3) further comprises an additional layer positioned above the layer (3a) as described above. In this case, the film (3) thus further comprises another layer (3b) forming a cooking face (4), said other layer (3b) comprising one or more polymers chosen from: 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; preferably PTFE; polyarylether ketones (PAEK), including polyether ketone (PEK), polyether ether ketone (PEEK), polyether ketone ketone (PEKK), polyether ether ketone ketone (PEEKK),polyether ketone ether ketone ketone (PEKEKK), preferably polyether ether ketone (PEEK), polyamideimide (PAI), polyimide (PI), polyetherimide (PEI), polybenzymidazole (PBI) and mixtures thereof, preferably mixtures of PTFE and PEEK. According to one embodiment, the film (3) further comprises at least one intermediate layer (3c) positioned between the layer (3a) and the other layer (3b), said intermediate layer (3c) comprising one or more polymers chosen from: polytetrafluoroethylene (PTFE), copolymers of tetrafluoroethylene and perfluoropropylvinylether (PFÀ), copolymers of tetrafluoroethylene and hexafluoropropene (FEP), polyvinylidene fluoride (PVDF), copolymers of tetrafluoroethylene and polymethylvinylether (MVÀ), terpolymers of tetrafluoroethylene, polymethylvinylether and fluoroalkylvinylether (TFE / PMVE / FÀVE), ethylene tetrafluoroethylene (ETFE),and mixtures thereof; preferably copolymers of tetrafluoroethylene and perfluoropropylvinylether (PFÀ) and PTFE; preferably PTFE polyarylether ketones (PAEK), including polyether ketone (PEK), polyether ether ketone (PEEK), polyether ketone ketone (PEKK), polyether ether ketone ketone (PEEKK), polyether ketone ether ketone ketone (PEKEKK), preferably polyether ether ketone (PEEK), polyamideimide (PAI), polyimide (PI), polyetherimide (PEI), polybenzymidazole (PBI) and mixtures thereof, preferably mixtures of polyarylether ketones (PAEK) and PTFE, preferably mixtures of PEEK and PTFE; PTFE being particularly preferred.,

[0065] The film (3) may also further comprise at least one filler and / or at least one reinforcement.

[0066] As fillers which can be used in the present invention, mention may in particular be made of metal oxides, metal carbides, metal oxynitrides, metal nitrides, silicas and their mixtures.

[0067] These fillers may be present in one or more layers of the film (3) or in each of the layers of the film (3).

[0068] Reinforcements that can be used in the present invention include mineral or metal reinforcement of the fiber type, metal mesh, fiberglass material or fabric. The reinforcement may also consist of a non-fluorinated polymer with high thermomechanical properties of the polyaryletherketone (PEAK) type, such as polyetheretherketone (PEEK), or polyamide-imide (PAI). The reinforcement may be in the form of a layer of film (3) positioned between the layer (3a) and the other layer (3b) forming the cooking face.

[0069] In order to improve the adhesion of the film (3) and the metal substrate (2), the layer (3a) of the film (3) coming into contact with the face (2a) of the metal substrate (2) during step (v) may have undergone a mechanical or chemical surface treatment. This surface treatment may be a chemical attack, brushing, hydration, sandblasting, shot blasting, a physicochemical treatment of the plasma or corona or laser type, a chemical activation or a combination of these different techniques.

[0070] According to one embodiment, the thickness of said film (3) is between 10 pm and 500 pm, preferably between 15 pm and 250 pm, particularly preferably between 25 pm and 150 pm.

[0071] The measurement of the thickness of the layer(s) of the film (3) is carried out at 20 random points on the section of the film. The average thickness of said film (3) is obtained by averaging these 20 measurements.

[0072] The total thickness of the film (3) of the coated cooking element (1) according to the invention, i.e. measured on the cooking element once it has been coated with the film (3), is between 10 μm and 500 μm, preferably between 15 μm and 250 μm, particularly preferably between 25 μm and 150 μm.

[0073] The measurement of the thickness of the film (3) of the coated cooking element (1) according to the invention is carried out at 20 random points on the section of the coated substrate. The average thickness of said film (3) is obtained by averaging these 20 measurements.

[0074] The film (3), before assembly with the metal substrate (2), can be obtained by depositing a first layer on a support, then possibly by the successive deposition of the other layers, then by exfoliation of said film to separate it from the support. The layers of the film (3) can also be assembled together by any other assembly process, such as by lamination for example.

[0075] Advantageously, the film (3) of the coated cooking element (1) completely covers the face (2a) of the metal substrate (2). In the embodiments illustrated in Figures 1, 2, 4 and 5, the film (3) comprises 3 layers: the layer (3a), the other layer (3b) and the intermediate layer (3c).

[0076] Structuring (5)

[0077] The cooking face (4) of the cooking element (1) as described above has a structure (5) constituting a relief characterized by a maximum profile height R t measured according to DIN 4768 E standard of January 1, 1990 between 10 and 500 pm, preferably between 20 and 100 pm.

[0078] The creation of a structure (5) on the cooking surface (4) makes the surface less smooth, less shiny and therefore limits the visibility of defects, whether they are appearance defects or scratches that may appear during use.

[0079] The creation of a relief characterized by a maximum profile height R t greater than 10 pm, preferably 20 pm, makes it possible to visually mask these defects and scratches.

[0080] However, the maximum profile height R t must remain limited so as not to degrade the performance as a cooking surface and thus avoid preferential fouling areas, for example in the hollows presented by the relief. It is thus less than 500 pm, preferably less than 100 pm.

[0081] The film (3) of the coated cooking element (1) has a thickness which is not constant due to the structuring (5) present on the cooking face (4). It has a minimum thickness or residual thickness noted E r , non-zero, so that the face (2a) of the metal substrate (2) is completely covered by the film (3).

[0082] This residual thickness E rallows non-stick properties to be maintained even in the event of scratches and progressive wear of the raised areas of the film (3).

[0083] According to one embodiment, the residual thickness E r of the film (3) is greater than or equal to 10 pm and is preferably greater than or equal to 20 pm.

[0084] The residual thickness E r of the film (3) is measured on a section of the coated cooking element (1). The maximum profile height Rt of the structuring (5) may be between 20% and 180%, preferably between 50% and 150%, particularly preferably between 80% and 120% of the thickness of said film (3).

[0085] The thickness of the film (3) of the coated cooking element (1) is measured according to the protocol described above.

[0086] The relief of the structuring (5) includes patterns constituted by local variations in the level of the surface of the cooking face (4).

[0087] According to one embodiment, the relief of the structuring (5) comprises periodic patterns or is made up of periodic patterns.

[0088] In this case, the relief of the structuring (5) may comprise the same elementary pattern which is repeated at regular intervals or be made up of the same elementary pattern which is repeated at regular intervals.

[0089] Advantageously, the relief of the structuring (5) is made up of patterns separated from each other by a pitch Ar corresponding to the distance between two patterns of the relief greater than 100 pm, preferably greater than 150 pm, even more preferably greater than 200 pm.

[0090] Advantageously, the relief of the structuring (5) does not include a periodic pattern or includes or is made up of patterns separated from each other by a pitch Ar corresponding to the distance between two patterns of the relief greater than 100 pm, preferably greater than 150 pm, even more preferably greater than 200 pm.

[0091] Figure 3 represents a schematic sectional view of a coated cooking element (1) comprising a metal substrate (2) coated with a film (3) forming a cooking face (4), said cooking face (4) having a structure (5) of maximum profile height R t and having a periodic pattern of Ar steps. The face (2a) of the metal substrate (2) is shown with surface roughness.

[0092] As shown in Figure 3, the points of the film (3) having the lowest altitude rise to an altitude higher than the altitude of the points of the metal substrate (2) having the highest altitude. Thus, as clearly visible in Figure 3, the film (3) forms a continuous base (3d) above the metal substrate (2), and the structuring (5) is formed above said continuous base (3d). In Figure 3, the minimum thickness or residual thickness noted E r corresponds to the thickness of the continuous base (3d). The residual thickness E r of the film (3) is less than the initial thickness Ef corresponding to the thickness of the film (3) as defined above.

[0093] Thus a notch affecting the film (3) will first concern the structuring (5) then the said continuous base (3d). A greater notch depth will be necessary to reach the metal substrate (2).

[0094] According to one embodiment, the relief of the structuring (5) comprises non-periodic patterns or is made up of non-periodic patterns.

[0095] Alternatively, the relief of the structuring (5) may include periodic patterns and / or non-periodic patterns.

[0096] The structuring (5) generates unevenness in the thickness of the film (3) which leads to variations in scratch resistance on said surface, which can contribute to preventing the formation of long scratches.

[0097] The structuring (5) can be present on all or part of the cooking surface (4).

[0098] Manufacturing process

[0099] The invention also relates to a method for manufacturing a coated cooking element (1) for a culinary article or electrical cooking appliance comprising a cooking face (4) having a structure (5) constituting a relief characterized by a maximum profile height R tmeasured according to standard DI N 4768 E of January 1, 1990 between 10 and 500 pm, preferably between 20 and 100 pm, said method comprising the following successive steps i. to v.: i. Providing a metal substrate (2) ii. Optionally, prior treatment of the face (2a) of said metal substrate (2) intended to be coated, iii. Providing a film (3) forming a cooking face (4) comprising a layer (3a) comprising one or more semi-crystalline or amorphous thermoplastic polymers, iv. Positioning the layer (3a) of the film (3) so that the layer (3a) is opposite said face (2a) of the metal substrate (2), v. Carrying out the assembly of said metal substrate (2) and said film (3) by hot pressing, said method further comprising a step vi. of creating said structuring (5), said steps v. and vi. being able to be simultaneous or successive.

[0100] The cooking element (1), the metal substrate (2), the film (3) and the structuring (5) of the cooking face (4) are as described above.

[0101] Step v) assembly

[0102] Step v. of assembling the metal substrate (2) and the film (3) is carried out by hot pressing.

[0103] Hot pressing means any method for assembling a metal substrate and a polymer film by applying a high temperature, generally higher than the lowest temperature among the melting points of the semi-crystalline thermoplastic polymers and the glass transition temperatures (Tg) of the amorphous thermoplastic polymers of the layer (3a) at the time of assembly, and a high pressure, generally higher than a few MPa, for a sufficient time, varying from less than one second to a few minutes.

[0104] The assembly can be carried out by thermal compression, in a static press or between rollers (roll-to-roll process). The pressures applied by thermal compression are generally a few MPa. The processing temperature is generally limited by the degradation temperature of the polymer film to be assembled.

[0105] The assembly can be carried out by hot stamping. In this case, the pressures applied are higher than with the thermal compression process, of the order of a few hundred MPa, and the stamping time is very short, typically of the order of a few seconds, which allows the use of higher temperatures.

[0106] Let us also mention, without limitation, assembly by solid state bonding.

[0107] Advantageously, the temperature of the film (3) at the end of step v. of assembling said film (3) and the metal substrate (2), i.e. when the assembly of the film (3) and the metal substrate (2) is no longer maintained under pressure, is lower than the lowest temperature among the melting points of the semi-crystalline thermoplastic polymers and the glass transition temperatures (Tg) of the amorphous thermoplastic polymers of the layer (3a).

[0108] After assembly, the metal substrate (2) coated with the film (3) is left to cool to room temperature in order to obtain maximum adhesion between the metal substrate (2) and the film (3).

[0109] Step vi) creation of the structure (5)

[0110] Step v) of assembling the metal substrate (2) and the film (3) and step vi) of creating the structuring (5) may be simultaneous or successive.

[0111] According to a variant of the method, the structuring (5) can be created on the cooking face (4) during the hot pressing of step v) or during a cold pressing step subsequent to this hot pressing: either by means of texturing (6) of the surface of the pressing tool coming into contact with the cooking face (4).

[0112] The texturing of the tool can be carried out by laser engraving, chemical engraving, electroerosion or even by mechanical engraving; or by means of a textured spacer (7) positioned between one face of the pressing tool and the film (3).

[0113] The spacer can be a textured metal material, a metal fabric, a welded wire mesh, a fiberglass woven fabric or a carbon fiber woven fabric.

[0114] According to one embodiment, steps v. and vi. are simultaneous and are carried out by means of a hydraulic or mechanical press comprising a lower tool (12A) and an upper tool (12B) between which the metal substrate (2) and the film (3) are assembled, and such that the plane of the surface of the tool coming into contact with the cooking face (4) has a texturing (6) making it possible to give said cooking face (4) said structuring (5).

[0115] Figure 4 illustrates such an embodiment according to which the upper tool (12B) has said texturing (6). According to another embodiment, steps v. and vi. are simultaneous and are carried out by means of a hydraulic or mechanical press comprising a lower tool (12A) and an upper tool (12B) between which the metal substrate (2) and the film (3) are assembled, and further comprising between step iv. and step v. a step iv(a). of positioning a textured spacer (7) so that the textured spacer is opposite the cooking face (4) of the film (3) and makes it possible to give said cooking face (4) said structuring (5) during the assembly step v.

[0116] Figure 5 illustrates such an embodiment.

[0117] According to another embodiment, steps v. and vi. are successive and step vi. is carried out by means of a hydraulic or mechanical press comprising a lower tool (12A) and an upper tool (12B) between which the metal substrate (2) and the film (3) assembled during step v. are cold pressed, and such that the plane of the surface of the tool coming into contact with the cooking face (4) during step vi. has a texturing (6) making it possible to give said cooking face (4) said structuring (5).

[0118] According to another embodiment, steps v. and vi. are successive and step vi. is a step of cold pressing the metal substrate (2) and the film (3) assembled during step v. with a textured spacer (7) positioned opposite the cooking face (4) and making it possible to give said cooking face (4) said structuring (5) during step vi.

[0119] In step vi., the film (3) flows into the patterns of the textured spacer (7) or into those of the texturing (6) of the surface of the pressing tool, thus allowing the creation of the structuring (5).

[0120] According to the method implemented during step vi, according to the maximum profile height R t desired and the thickness of the film (3), deformation of the film (3) may occur with or without deformation of the metal substrate (2).

[0121] The metal substrate (2) coated with the film (3) whose cooking face (4) has the structuring (5) can then be shaped by stamping, then if necessary by drawing. According to another variant of the method, the structuring (5) of the cooking face (4) can also be carried out by mechanical abrading of the surface of the film (3).

[0122] Said structuring (5) can be carried out: either directly after the assembly of the film (3) and the metal substrate (2), or after a step of shaping the cooking element (1).

[0123] According to one embodiment, steps v. and vi. are successive and step vi. is a step of mechanical treatment of the cooking face (4) of the metal substrate (2) and the film (3) assembled during step v.

[0124] Said mechanical treatment may be brushing, grinding, sandblasting, shot blasting, micro-shot blasting, shot blasting or a combination of these techniques.

[0125] An abrasive is then used for the mechanical treatment of the cooking face (4) whose characteristics (nature, shape, size) are chosen according to the structuring (5) desired for said cooking face (4).

[0126] For example, the element to be textured can be placed on a lathe and thus a structure (5) with a circular pattern can be generated.

[0127] The metal substrate (2) coated with the film (3) can then be shaped by stamping, then if necessary by stretching.

[0128] The adhesion of the film (3) to the metal substrate (2) before shaping must be good enough to avoid any loss of adhesion during and after the shaping operation.

[0129] The shaping of the metal substrate (2) coated with the film (3) can take place before step vi. of creating the structuring (5) by mechanical treatment of the cooking face (4).

[0130] According to one embodiment, the method thus further comprises, between step v. and step vi. of mechanical treatment, a step v(a). of shaping by stamping, then if necessary stretching, of the metal substrate (2) and the film (3) assembled during step v. Step vi. of creating said structuring (5) is carried out on all or part of said cooking face (4).

[0131] Figure 6 illustrates a coated cooking element (1) according to the invention forming a cooking container. The film (3) assembled with the metal substrate (2) forms the cooking face (4) arranged inside the cooking container.

[0132] Culinary article

[0133] Another object of the invention relates to a culinary article (100) comprising a coated cooking element (1) as described above or obtained according to the method as described above.

[0134] The coated cooking element (1) according to the method of the invention can form a cooking container in a culinary article (100).

[0135] According to an embodiment illustrated in Figure 7, the culinary article (100) comprises a heating face (8) intended to be brought into contact with an external heating source, the heating face (8) being opposite the cooking face (4) intended to be brought into contact with the food during cooking. The culinary article (100) is further equipped with a gripping member (9) fixed to said coated cooking element (1).

[0136] According to one embodiment, the culinary article (100) comprises a coated cooking element (1) comprising a base (10) and a side wall (11) and such that the cooking face (4) at said base has said structuring (5).

[0137] According to a variant of this embodiment, only the base (10) has the structure (5).

[0138] According to another variant of this embodiment, the bottom (10) and the side wall (11) have the structure (5).

[0139] Preferably the structuring (5) extends over the entire bottom (10).

[0140] When present on the side wall (11), the structuring (5) does not necessarily extend over the entire side wall (11). According to a preferred embodiment, the entire cooking face (4) of the coated cooking element (1) has the structuring (5). The coated cooking element (1) is then shaped by stamping, and if necessary stretching, so that the base (10) and the side wall (11) have the structuring (5).

[0141] According to a preferred embodiment, after stamping, and where appropriate stretching, only the bottom (10) of the cooking element (1) of the culinary article (100) has the structure (5).

[0142] The cooking article (100) can be chosen from the group consisting of saucepan, frying pan, skillets or pots for fondue or raclette, stewpot, wok, sauté pan, crepe pan, grill, griddle, pot, casserole dish, cooker or bread machine bowl, cooking mold.

[0143] Electric cooking appliance

[0144] Another object of the invention relates to an electrical cooking appliance (200) comprising a coated cooking element (1) as described above or obtained according to the method described above and a heating source (210) configured to heat said coated cooking element (1).

[0145] The coated cooking element (1) according to the method of the invention can form a cooking container in an electric cooking appliance (200).

[0146] According to an embodiment illustrated in Figure 8, the electrical cooking appliance (200) according to the invention comprises a coated cooking element (1) and a heating source (210) configured to heat said coated cooking element (1). The coated cooking element (1) forming a cooking container is arranged in a heating base (230) comprising the heating source (210) composed of several heating elements (220). The face (8) rests on the heating elements (220). If desired, the face (8) can be integral with the heating elements (220).

[0147] According to one embodiment, the electrical cooking appliance (200) comprises a coated cooking element (1) comprising a bottom (10) and a side wall (11) and such that the cooking face (4) at said bottom has said structuring (5).

[0148] According to a variant of this embodiment, only the base (10) has the structure (5). According to another variant of this embodiment, the base (10) and the side wall (11) have the structure (5).

[0149] Preferably the structuring (5) extends over the entire bottom (10). When it is present on the side wall (11), the structuring (5) does not necessarily extend over the entire side wall (11).

[0150] The electric cooking appliance (200) can be chosen from the group consisting of electric crepe maker, electric raclette appliance, electric fondue appliance, electric grill, electric griddle, electric cooker, bread machine.

Claims

CLAIMS 1. Coated cooking element (1) for a cooking article or electrical cooking appliance, comprising a metal substrate (2) coated on at least one face (2a) with a film (3) forming a cooking face (4), said film (3) comprising a layer (3a) arranged on the side opposite the cooking face (4), said layer (3a) comprising one or more semi-crystalline or amorphous thermoplastic polymers, said film (3) being assembled with said metal substrate (2), said layer (3a) being in contact with the face (2a) of the metal substrate (2), and such that said cooking face (4) has a structure (5) constituting a relief characterized by a maximum profile height R t measured according to standard DI N 4768 E of January 1, 1990 between 10 and 500 pm, preferably between 20 and 100 pm.

2. Coated cooking element (1) according to claim 1 characterized in that said metal substrate (2) is an aluminum substrate, stainless steel or a multi-layer metal substrate.

3. Coated cooking element (1) according to any one of the preceding claims, characterized in that the face (2a) of the metal substrate (2) has undergone a surface treatment prior to the assembly of the film (3) with the face (2a) of the metal substrate (2).

4. Coated cooking element (1) according to any one of the preceding claims, characterized in that the thickness of said film (3) is between 10 pm and 500 pm, preferably between 15 pm and 250 pm, particularly preferably between 25 pm and 150 pm.

5. Coated cooking element (1) according to any one of the preceding claims, characterized in that the residual thickness E rof the film (3) is greater than or equal to 10 pm, preferably greater than or equal to 20 pm.

6. Coated cooking element (1) according to any one of the preceding claims, characterized in that the crystalline or amorphous thermoplastic polymer(s) of the layer (3a) are chosen from: polytetrafluoroethylene (PTFE), copolymers of tetrafluoroethylene and perfluoropropylvinylether (PFÀ), copolymers of tetrafluoroethylene and hexafluoropropene (FEP), polyvinylidene fluoride (PVDF), copolymers of tetrafluoroethylene and polymethylvinylether (MVÀ), terpolymers of tetrafluoroethylene, polymethylvinylether and fluoroalkylvinylether (TFE / PMVE / FÀVE), ethylene tetrafluoroethylene (ETFE), and mixtures thereof polyarylether ketones (PAEK), including polyether ketone (PEK), polyether ether ketone (PEEK), polyether ketone ketone (PEKK), polyether ether ketone ketone (PEEKK), polyether ketone ether ketone ketone (PEKEKK), preferably polyether ether ketone (PEEK) polyamideimide (PAI), polyimide (PI), polyetherimide (PEI), polybenzymidazole (PBI) and mixtures thereof.

7. Coated cooking element (1) according to any one of the preceding claims, characterized in that said film (3) consists of a single layer (3a) also forming a cooking face (4).

8. Coated cooking element (1) according to any one of claims 1 to 6, characterized in that said film (3) further comprises another layer (3b) forming a cooking face (4), said other layer (3b) comprising one or more polymers chosen from: 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;preferably PTFE polyarylether ketones (PAEK), including polyether ketone (PEK), polyether ether ketone (PEEK), polyether ketone ketone (PEKK), polyether ether ketone ketone (PEEKK), polyether ketone ether ketone ketone (PEKEKK), preferably polyether ether ketone (PEEK) polyamideimide (PAI), polyimide (PI), polyetherimide (PEI), polybenzymidazole (PBI) and mixtures thereof, preferably mixtures of PTFE and PEEK.; 9. Coated cooking element (1) according to claim 8 characterized in that the film (3) further comprises at least one intermediate layer (3c) positioned between the layer (3a) and the other layer (3b), said intermediate layer (3c) comprising one or more polymers chosen from: polytetrafluoroethylene (PTFE), copolymers of tetrafluoroethylene and perfluoropropylvinylether (PFÀ), copolymers of tetrafluoroethylene and hexafluoropropene (FEP), polyvinylidene fluoride (PVDF), copolymers of tetrafluoroethylene and polymethylvinylether (MVÀ), terpolymers of tetrafluoroethylene, polymethylvinylether and fluoroalkylvinylether (TFE / PMVE / FÀVE), ethylene tetrafluoroethylene (ETFE), and mixtures thereof; preferentially copolymers of tetrafluoroethylene and perfluoropropylvinylether (PFÀ) and PTFE;preferably PTFE polyarylether ketones (PAEK), including polyether ketone (PEK), polyether ether ketone (PEEK), polyether ketone ketone (PEKK), polyether ether ketone ketone (PEEKK), polyether ketone ether ketone ketone (PEKEKK), preferably polyether ether ketone (PEEK), polyamideimide (PAI), polyimide (PI), polyetherimide (PEI), polybenzymidazole (PBI) and mixtures thereof, preferably mixtures of polyarylether ketones (PAEK) and PTFE, preferably mixtures of PEEK and PTFE; PTFE being particularly preferred.; 10. Coated cooking element (1) according to any one of the preceding claims, characterized in that said structuring (5) is present on all or part of said cooking face (4).

11. Method for manufacturing a coated cooking element (1) for a culinary article or electrical cooking appliance comprising a cooking face (4) having a structure (5) constituting a relief characterized by a maximum profile height Rt measured according to standard DIN 4768 E of January 1, 1990 of between 10 and 500 pm, preferably between 20 and 100 pm, said method comprising the following successive steps i. to v.: i. Provision of a metal substrate (2), ii. Optionally, prior treatment of the face (2a) of said metal substrate (2) intended to be coated, iii. Providing a film (3) forming a cooking face (4) comprising a layer (3a) comprising one or more semi-crystalline or amorphous thermoplastic polymers, iv. Positioning the layer (3a) of the film (3) so that the layer (3a) faces said face (2a) of the metal substrate (2), v. Carrying out the assembly of said metal substrate (2) and said film (3) by hot pressing, said method further comprising a step vi. of creating said structuring (5), said steps v. and vi. being able to be simultaneous or successive.

12. Method according to claim 11 characterized in that steps v. and vi. are simultaneous and are carried out by means of a hydraulic or mechanical press comprising a lower tool (12A) and an upper tool (12B) between which the metal substrate (2) and the film (3) are assembled, and such that the plane of the surface of the tool coming into contact with the cooking face (4) has a texturing (6) making it possible to give said cooking face (4) said structuring (5).

13. Method according to claim 11 characterized in that steps v. and vi. are simultaneous and are carried out by means of a hydraulic or mechanical press comprising a lower tool (12A) and an upper tool (12B) between which the metal substrate (2) and the film (3) are assembled, and further comprising between step iv. and step v. a step iv(a). of positioning a textured spacer (7) so that the textured spacer is opposite the cooking face (4) of the film (3) and makes it possible to give said cooking face (4) said structuring (5) during the assembly step v.

14. Method according to claim 11 characterized in that steps v. and vi. are successive and in that step vi. is carried out by means of a hydraulic or mechanical press comprising a lower tool (12A) and an upper tool (12B) between which the metal substrate (2) and the film (3) assembled during step v. are cold pressed, and such that the plane of the surface of the tool coming into contact with the cooking face (4) during step vi. has a texturing (ô) making it possible to give said cooking face (4) said structuring (5).

15. Method according to claim 11 characterized in that steps v. and vi. are successive and in that step vi. is a step of cold pressing the substrate. Metallic TJ (2) and film (3) assembled during step v. with a textured spacer (7) positioned opposite the cooking face (4) and making it possible to give said cooking face (4) said structuring (5) during step vi.

16. Method according to claim 11 characterized in that steps v. and vi. are successive and in that step vi. is a step of mechanical treatment of the cooking face (4) of the metal substrate (2) and of the film (3) assembled during step v.

17. Method according to claim 16 characterized in that said mechanical treatment is brushing, grinding, sandblasting, shot blasting, micro-shot blasting, shot blasting or a combination of these techniques.

18. Method according to claim 16 or claim 17 characterized in that it further comprises between step v. and step vi. a step v(a). of shaping by stamping, then if necessary stretching, the metal substrate (2) and the film (3) assembled during step v.

19. Method according to any one of claims 11 to 18, characterized in that step vi. of creating said structuring (5) is carried out on all or part of said cooking face (4).

20. Culinary article (100) comprising a coated cooking element (1) according to any one of claims 1 to 10 or obtained according to the method of any one of claims 11 to 19.

21. Culinary article (100) according to claim 20 characterized in that it comprises a heating face (8) intended to be placed in contact with an external heating source, the heating face (8) being opposite the cooking face (4) intended to be placed in contact with the food during cooking.

22. Culinary article according to claim 21 characterized in that the cooking element (1) comprises a base and a side wall and in that the cooking face (4) at the level of said base has said structure (5).

23. Culinary article (100) according to one of claims 20 to 22 chosen from the group consisting of saucepan, frying pan, skillets or caquelons for fondue or raclette, everything, wok, sauté pan, crepe pan, grill, griddle, pot, casserole dish, cooker or bread machine bowl, cooking mold.

24. Electrical cooking appliance (200) comprising a coated cooking element (1) and a heating source (210) configured to heat said coated cooking element (1), characterized in that said coated cooking element (1) is in accordance with any one of claims 1 to 10 or obtained according to the method of any one of claims 11 to 19.

25. Electrical cooking appliance (200) according to claim 24 characterized in that the cooking element (1) comprises a bottom and a side wall and in that the cooking face (4) at said bottom has said structuring (5).

26. Electric cooking appliance (200) according to claim 24 or 25, chosen from the group consisting of electric crepe maker, electric raclette appliance, electric fondue appliance, electric grill, electric griddle, electric cooker, bread machine.

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