Method for bonding an adhesion-preventing film to a metal substrate by hot stamping

Abstract

The present invention relates to a method for manufacturing a coated cooking body (1), the manufacturing method comprising: i. a step of preparing a metal substrate (2) and a metal mesh (3), wherein the metal substrate (2) has a surface (2a) intended to be brought into contact with the metal mesh (3), the step of preparing the metal substrate (2) and the metal mesh (3); ii. a step of attaching the metal mesh (3) to the surface (2a) of the metal substrate (2); iii. a step of preparing a film (4), wherein the film (4) includes a layer (4a) containing one or more semi-crystalline or amorphous thermoplastic polymers, the layer (4a) being intended to be brought into contact with the surface (2a) of the metal substrate (2) and the metal mesh (3), the step of preparing the film (4); iv. a step of heating the metal substrate (2) and the metal mesh (3); v. a step of arranging the film (4) such that the layer (4a) faces the surface (2a) of the metal substrate (2) and the metal mesh (3) heated in step iv; vi. a step of bonding the metal substrate (2) and the metal mesh (3) to the film (4) by hot stamping, wherein the metal substrate (2) and the metal mesh (3) are at a temperature higher than the lowest of the melting point of the semi-crystalline thermoplastic polymer and the glass transition temperature (Tg) of the amorphous thermoplastic polymer of the layer (4a) during bonding, the step of bonding.

Description

Technical Field

[0001] The present invention relates to the field of methods for obtaining a cooked body coated with an anti-adhesion polymer film.

Background Art

[0002] State of the Art In the manufacturing industry of cooking utensils having an anti-adhesion cooking surface, the performance of the anti-adhesion coating and the development of methods for obtaining such a coating are important concerns.

[0003] Conventionally, first, a metal substrate is formed to form a cooking utensil, and then the inner surface of the cooking utensil is coated with a fluororesin having excellent heat resistance such as polytetrafluoroethylene (PTFE) or tetrafluoroethylene-perfluoroalkyl vinyl ether (PFA) by a liquid spray coating method or a powder coating method. Another method is to coat the substrate and then form the coated substrate.

[0004] The liquid spray coating method has many drawbacks. When the metal substrate has a curved shape, it is difficult to obtain a uniform coating thickness. Also, the liquid spray coating method involves the use of solvents or volatile organic compounds that must be evaporated, recovered, and recycled during the process. From an environmental perspective, a method that does not use solvents and volatile organic compounds is preferred. On the other hand, the coating thickness is limited. If the coating thickness is too thick, there is a risk of cracking.

[0005] The powder coating method also has drawbacks. The resulting coating has pinhead-type defects that can lead to a decrease in anti-adhesion properties.

[0006] The coatings obtained by these two methods can have a fairly large surface roughness, which can cause cleaning problems because cooking residues can remain on the coating surface even after several washings.

[0007] When facing mechanical stress peculiar to the use of cooking utensils, loss of the mechanical properties of the coating is observed, and peeling of the coating may occur at the interface with the metal substrate.

[0008] To overcome the above drawbacks, the state of the art describes a metal substrate coated with a fluorinated film by lamination.

[0009] Korean Patent Application No. 2015-0030719 describes a kitchen utensil comprising a body including a metal substrate laminated with a film of a fluororesin. Also described is a method for obtaining the kitchen utensil. In Example 1, a PTFE multilayer film is used without information on the nature of the layer. The operation of laminating the film on the substrate is not described.

[0010] Korean Patent Application No. 2016-0099388 describes a method for obtaining a metal substrate coated with a fluorinated film (lacking an undercoat layer containing an organic compound or an adhesive). The fluorinated film is a multilayer film obtained by continuously depositing an aqueous dispersion of the constituents of the layer to be dried and sintered (fluorinated resin and, optionally, an inorganic filler) on a support. Thereafter, the multilayer film is peeled off from its support and placed on the metal substrate before bonding. The layer of the fluorinated film in contact with the metal consists of a resin selected from PTFE and FEP, PFA, TFM, MFA (or mixtures thereof) having good flow characteristics, thus enabling good adhesion not possible with PTFE. The metal substrate / fluorinated film combination is carried out by thermocompression bonding, static pressing, or between rollers (roll-to-roll method). In the static bonding method, both the substrate and the film are heated to a temperature composed between 300 °C and 410 °C with an applied pressure of 100 - 800 psi (0.7 Mpa - 5.6 MPa). In the roll-to-roll bonding method (difficult to implement when the metal substrate has a fairly large thickness), both the substrate and the film are heated to a temperature composed between 330 °C and 420 °C with an applied pressure composed between 2 Mpa and 15 MPa.

[0011] In a modification of both methods, the pressure applied during bonding is several MPa, and the operating temperature is limited by the degradation temperature of the fluorinated film (in particular, the degradation temperature of PTFE starting at 420 °C). Therefore, the bonding rate between the polymer film and the metal substrate is limited by the parameters of the bonding method.

[0012] Furthermore, the method for obtaining a substrate coated by lamination of a fluorinated film offers the possibility of having a thicker and thus more resistant anti-adhesion coating, however, the mechanical properties of such a film are not optimal. Summary of the Invention Problems to be Solved by the Invention

[0013] Disclosure of the Invention From an industrial perspective, there is a need to develop a method for bonding a polymer film onto a metal substrate that is more advantageous in terms of bonding time and enables the obtaining of a coating that is superior in terms of durability.

[0014] Therefore, the applicant has developed a method for manufacturing a cookware body coated by hot stamping bonding of a metal substrate and a polymer film, and the bonding thereof comprises a metal reinforcing element between the metal substrate and the polymer film. Means for Solving the Problems

[0015] Summary of the Invention The inventors have found that the method according to the invention makes it possible to achieve a rapid bonding between a metal substrate and a polymer film comprising one or more semi-crystalline or amorphous thermoplastic polymers, while ensuring good adhesion of the polymer film to the metal substrate.

[0016] Unlike conventional methods for bonding a fluororesin film to a metal, such as hot pressing, according to the method of the present invention, preferably only the substrate is heated before bonding. The polymer film is essentially heated by conduction when brought into contact with the substrate during bonding and is then cooled by the thermal inertia of the bonding tool to a temperature lower than the heating temperature of the metal substrate.

[0017] Therefore, during bonding, particularly at the interface between the substrate and the film, very locally, a polymer film containing one or more semi-crystalline or amorphous thermoplastic polymers can be heated to a temperature exceeding the melting temperature or glass transition temperature of all or part of the thermoplastic polymer for a very short time without causing degradation of the film.

[0018] This execution of high temperature combined with the pressure applied during stamping enables the bonding of the polymer film to the metal substrate to be carried out in a much shorter time than by conventional methods of bonding polymer films to metal substrates, such as hot pressing.

[0019] Furthermore, before bonding to the polymer film, a metal reinforcing material in the shape of a metal mesh is attached to the metal substrate. The presence of this reinforcing material makes it possible to improve the mechanical properties of the coated metal substrate. Thereby, the bonding force between the metal substrate and the polymer film is strengthened. The metal reinforcing material makes it possible to improve the performance of the anti-adhesion cooking surface, particularly by improving the scratch resistance of the anti-adhesion coating.

[0020] Therefore, the present invention relates to a method for manufacturing a coated cooking body (1), the manufacturing method comprising: i. a step of preparing a metal substrate (2) and a metal mesh (3), wherein the metal substrate (2) has a surface (2a) intended to be brought into contact with the metal mesh (3), the step of preparing the metal substrate (2) and the metal mesh (3); ii. a step of attaching the metal mesh (3) to the surface (2a) of the metal substrate (2); iii. A step of preparing a film (4), wherein the film (4) comprises a layer (4a) containing one or more semi-crystalline or amorphous thermoplastic polymers, and the layer (4a) is intended to be brought into contact with the surface (2a) of the metal substrate (2) and the metal mesh (3), the step of preparing the film (4); iv. A step of heating the metal substrate (2) and the metal mesh (3); v. A step of arranging the film (4) such that the layer (4a) faces the surface (2a) of the metal substrate (2) and the metal mesh (3) heated in step iv; vi. A step of bonding the metal substrate (2) and the metal mesh (3) to the film (4) by hot stamping, wherein the metal substrate (2) and the metal mesh (3) are at a temperature higher than the lowest temperature among the melting point of the semi-crystalline thermoplastic polymer of the layer (4a) and the glass transition temperature (Tg) of the amorphous thermoplastic polymer at the time of bonding.

[0021] The present invention also relates to a method of forming the coated cooking body described above, comprising a step (a) of press-molding the coated cooking body (1) obtained at the end of step (vi).

[0022] Another aspect of the present invention is as described below and in the claims.

[0023] Definitions The term "film" is understood to mean, in the context of the present invention, a single layer intended to be bonded to a metal substrate, or a set consisting of two or more superposed layers. Also, the term "film" corresponds to the set once bonded to the metal substrate.

[0024] The term "layer" is understood to mean, in the context of the present invention, a continuous layer. A continuous layer (also referred to as a monolithic layer) is a single entity that forms a total flat area that completely covers the surface on which it is placed or is to be placed.

[0025] For the purposes of the present invention, the term "hot stamping" means a method of joining a pre-heated metallic substrate (2) and a metallic mesh (3), as well as a polymer film (4) between a lower tool and an upper tool.

[0026] For the purposes of the present invention, the term "aluminum alloy" means aluminum alloys of the 1000 series, 2000 series, 3000 series, 4000 series, 5000 series, 6000 series, 7000 series and 8000 series.

Brief Description of the Drawings

[0027]

Figure 1

Figure 2

Figure 3

Figure 4a

Figure 4b

Figure 4c

Mode for Carrying Out the Invention

[0028] Detailed Description of the Invention The inventors have developed a manufacturing method that meets the indicated needs.

[0029] Accordingly, the present invention relates to a method for manufacturing a coated cooking body (1), the manufacturing method comprising: i. providing a metal substrate (2) and a metal mesh (3), the metal substrate (2) having a surface (2a) intended to be brought into contact with the metal mesh (3), the step of providing the metal substrate (2) and the metal mesh (3), ii. attaching the metal mesh (3) to the surface (2a) of the metal substrate (2), iii. providing a film (4), the film (4) comprising a layer (4a) containing one or more semi-crystalline or amorphous thermoplastic polymers, the layer (4a) being intended to be brought into contact with the surface (2a) of the metal substrate (2) and the metal mesh (3), the step of providing the film (4), iv. heating the metal substrate (2) and the metal mesh (3), v. placing the film (4) such that the layer (4a) faces the surface (2a) of the metal substrate (2) and the metal mesh (3) heated in step iv, and vi. A step of bonding the metal substrate (2) and the metal mesh (3) to the film (4) by hot stamping, wherein the metal substrate (2) and the metal mesh (3) are at a temperature higher than the lowest temperature among the melting point of the semi-crystalline thermoplastic polymer and the glass transition temperature (Tg) of the amorphous thermoplastic polymer of layer (4a) at the time of bonding.

[0030] Advantageously, steps i. to vi. are carried out continuously.

[0031] The metal substrate (2) used in step i of the method As the metal substrate (2) that can be used in the context of the present invention, mention may advantageously be made of a substrate made of aluminum, stainless steel, cast iron or cast aluminum, or titanium or copper.

[0032] For the purposes of the present invention, aluminum means a metal consisting of 100% aluminum or an aluminum alloy.

[0033] Advantageously, the metal substrate (2) is an aluminum substrate, a stainless steel substrate, or a multi-layer, especially a two-layer or three-layer metal substrate, and these multi-layers can be obtained, for example, by co-lamination, thermal diffusion under load (solid bonding), or hot or cold stamping (impact bonding).

[0034] Preferably, the metal substrate (2) comprises an alternating laminate of layers of metal and / or metal alloy.

[0035] According to one embodiment, the metal substrate (2) is an aluminum alloy substrate, a stainless steel substrate, or a multi-layer metal substrate whose surface (2a) consists of an aluminum alloy or stainless steel.

[0036] Preferably, the metal substrate (2) is an aluminum substrate.

[0037] Advantageously, the thickness of the metal substrate (2) is configured to be between 0.5 mm and 10 mm.

[0038] Advantageously, the surface (2a) of the metal substrate (2) is subjected to a surface treatment before bonding with the film (4), making it possible to improve the adhesion of the film to the substrate.

[0039] According to one embodiment, the surface of the surface (2a) of the metal substrate (2) is subjected to a surface treatment, and the surface treatment is chemical corrosion, brushing, hydration, sandblasting, shot peening, plasma or corona or laser type physico-chemical treatment, chemical activation, or a combination of these different techniques.

[0040] The metal mesh (3) used in step i of the present method The metal mesh means not only a metal mesh composed of wires intersecting each other, but also a punched metal sheet provided with holes, or an expanded metal mesh.

[0041] Advantageously, the metal mesh (3) is a woven metal mesh or an expanded metal mesh, preferably made of stainless steel.

[0042] The metal mesh (3) can have a thickness configured between 50 μm and 800 μm, preferably between 150 μm and 500 μm.

[0043] Therefore, when the metal mesh (3) is woven, the wires can have a diameter (or thickness) configured between 50 μm and 800 μm, preferably between 150 μm and 500 μm.

[0044] When the metal mesh (3) is made of expanded metal, the mesh can have a thickness configured between 50 μm and 800 μm, preferably between 150 μm and 500 μm.

[0045] When the metal mesh (3) is woven, the metal wires woven in the same direction are advantageously spaced from each other between 0.2 mm and 8 mm.

[0046] The void areas of the pattern, i.e., the woven metal mesh or expanded metal mesh, can all be the same or, conversely, different.

[0047] Figures 2 and 3 show, respectively, a woven metal mesh and an expanded metal mesh that can be used in the context of the present invention.

[0048] The metal mesh (3) has dimensions smaller than those of the metal substrate (2).

[0049] According to one embodiment, the metal mesh (3) is surface-treated, and the surface treatment is chemical corrosion, brushing, hydration, sandblasting, shot peening, physical and chemical treatment of the plasma or corona or laser type, chemical activation, or a combination of these different techniques.

[0050] Step (ii) of attaching the metal mesh (3) to the surface (2a) of the metal substrate (2) The metal mesh (3) is applied to the surface (2a) of the metal substrate (2).

[0051] The metal mesh (3) is attached to the surface (2a) by attachment points or die pressing so as to at least partially embed it in the surface of the metal substrate (2).

[0052] Attaching the metal mesh (3) by attachment points means that the metal mesh (3) is pre-crimped to the metal substrate (2) at several points rather than over its entire surface in contact with the metal substrate (2). This attachment makes it possible to position the metal mesh (3) on the metal substrate (2) for subsequent steps of the method.

[0053] Advantageously, the attachment of the metal mesh (3) to the surface (2a) of the metal substrate (2) is obtained by die pressing for at least partially embedding the metal mesh (3) in the surface (2a).

[0054] Form pressing means an operation that, for example, uses a drop hammer or a punch using a press machine to form press the metal mesh (3) at least partially into the surface of the metal substrate (2), or, for example, strongly compresses the metal mesh (3) with a surface or a roller.

[0055] Unlike attachment by anchor points, the form pressing operation is performed over the entire surface of the metal mesh (2).

[0056] Advantageously, the form pressing operation is performed using a press machine at room temperature.

[0057] The depth of the metal mesh (3) depends on characteristics such as the force applied during form pressing, the relative hardness of the metals of the metal mesh (3) and the metal substrate (2), and the diameter of the wire of the metal mesh (3).

[0058] According to one embodiment, the metal mesh (3) is only partially embedded in the surface of the metal substrate (2) and constitutes a protrusion.

[0059] According to another embodiment, the metal mesh (3) is completely embedded in the surface of the metal substrate (2).

[0060] When the metals of the metal mesh (3) and the metal substrate (2) are different, the form pressing can produce a composite substrate having characteristics resulting from the characteristics of the two metals. Thus, when the metal mesh (3) is made of a metal harder than the metal base material (2), the mechanical properties of the base metal, for example, the tendency of the base metal to deform at high temperatures, will be changed and it will be reduced.

[0061] The metal mesh (3) after attachment onto the metal base material (2) can generate a surface structuring that enables an increase in the contact surface with the film (4), and thus improves the bonding strength of the bonded body.

[0062] The set of the metal substrate (2) and the metal mesh (3) can be surface-treated after the mounting step, and the surface treatment is chemical corrosion, brushing, hydration, sandblasting, shot peening, physical and chemical treatment of plasma or corona or laser type, chemical activation, or a combination of these different techniques.

[0063] Advantageously, the arithmetic mean roughness Ra of the surface of the surface (2a) of the metal substrate (2) is 1 μm or more, preferably 2 μm or more.

[0064] Advantageously, the arithmetic mean roughness Ra of the surface of the surface (2a) of the metal substrate (2) is 20 μm or less.

[0065] Advantageously, the arithmetic mean roughness Ra of the surface of the surface (2a) of the metal substrate (2) is in the range of 2 μm to 10 μm.

[0066] The arithmetic mean roughness Ra is measured using a roughness meter in accordance with ISO standard 4287. Ra represents the arithmetic mean of the deviations from the mean. The surface shape can be investigated using a profilometer having a probe with a fine stylus having a diamond tip, or an optical measuring device such as Altisurf (registered trademark) that enables non-contact measurement by a chromatic confocal sensor. This investigation of the surface shape makes it possible to define the arithmetic mean roughness Ra.

[0067] The film (4) used in step iii of the present method The film (4) comprises a layer (4a) containing one or more semi-crystalline or amorphous thermoplastic polymers, and the layer (4a) is intended to be arranged in contact with the surface (2a) of the metal substrate (2) and the metal mesh (3).

[0068] The melting point of the semi-crystalline thermoplastic polymer and the glass transition temperature (Tg) of the amorphous thermoplastic polymer in the film (4) can be determined by thermal analysis methods such as differential thermal analysis (or DSC for differential scanning calorimetry), or dynamic mechanical analysis (DMA).

[0069] According to one embodiment, the film (4) comprises a single layer (4a) made of one or more semi-crystalline or amorphous thermoplastic polymers that form a cooking surface (5).

[0070] According to another configuration, the film (4) further comprises one or more layers, each of which contains one or more semi-crystalline or amorphous thermoplastic polymers.

[0071] According to one embodiment, the semi-crystalline or amorphous thermoplastic polymer(s) of the layer (4a) of the film (4) and, optionally, the additional layer(s) (if any), which may be the same or different, are - Polytetrafluoroethylene (PTFE), a copolymer of tetrafluoroethylene and perfluoropropyl vinyl ether (PFA), a copolymer of tetrafluoroethylene and hexafluoropropene (FEP), polyvinylidene fluoride (PVDF), a copolymer of tetrafluoroethylene and polymethyl vinyl ether (MVA), a tetrafluoroethylene terpolymer, polymethyl vinyl ether, and fluoroalkyl vinyl ether (TFE / PMVE / FAVE), ethylene tetrafluoroethylene (ETFE), and mixtures thereof, - Polyaryl ether ketone (PAEK) including polyether ketone (PEK), polyether ether ketone (PEEK), polyether ketone ketone (PEKK), polyether ether ketone ketone (PEEKK), polyether ketone ether ketone ketone (PEKEKK), preferably polyether ether ketone (PEEK), - Poly(arylene sulfide) (PAS) including poly(phenylene oxide) (PPO), poly(aryl ether sulfone) polymer (PAES) including polyether sulfone (PES), polyphenylene ether sulfone (PPSU), poly(phenylene sulfide) (PPS), liquid crystal polymer, - Polyamideimide (PAI), polyimide (PI), polyetherimide (PEI), polybenzimidazole (PBI), - and mixtures thereof, selected from the group consisting of.

[0072] Further, the film (4) may further contain at least one filler and / or at least one reinforcing material.

[0073] As fillers that can be used in the present invention, in particular, metal oxides, metal carbides, metal oxynitrides, metal nitrides, silica, and mixtures thereof may be mentioned.

[0074] These fillers may be present in one or more layers of the film (4) or in each layer of the film (4).

[0075] As a reinforcing material that can be used under the present invention, fibrous mineral or metal reinforcing materials, metal meshes, glass fiber materials or fabrics may be mentioned. The reinforcing material may also consist of a non-fluorinated polymer having high thermomechanical properties of the polyaryletherketone (PEAK) type, such as polyetheretherketone (PEEK) or polyamideimide (PAI), for example. The reinforcing material may be in the form of a layer of the film (4) positioned between the layer (4a) and the layer (4) forming the cooking surface.

[0076] In order to improve the adhesiveness between the film (4) and the metal substrate (2), during step (vi), the surface (2a) of the metal substrate (2) and the layer (4a) of the film (4) that contacts the metal mesh (3) may be subjected to a mechanical or chemical surface treatment. The surface treatment may be chemical corrosion, brushing, hydration, sandblasting, shot peening, plasma or corona or laser type physicochemical treatment, chemical activation, or a combination of these different techniques.

[0077] According to one embodiment, the thickness of the film (4) is configured to be between 5 μm and 500 μm, preferably between 25 μm and 150 μm.

[0078] The thickness of the layer of the film (4) is measured at 20 random points on the cross-section of the film. The average thickness of the film (4) is obtained by averaging these 20 measured values.

[0079] The total thickness of the film (4) of the coated food product (1) according to the invention, i.e. the thickness measured on the food product when the food product (1) is coated with the film (4), is between 5 μm and 500 μm, preferably between 25 μm and 150 μm.

[0080] The measurement of the thickness of the film (4) of the coated food product (1) according to the invention is carried out at 20 random points on the cross-section of the coated substrate. The average thickness of the film (4) is obtained by averaging these 20 measured values.

[0081] The film (4) can be obtained by depositing a first layer on a support before bonding with the metal substrate (2), then, possibly, continuously depositing other layers, and then separating the film from the support by peeling the film. The layers of the film (4) can also be bonded together by any other bonding method, such as lamination for example.

[0082] Generally, the film (4) of the coated food product (1) completely covers the face (2a) of the metal substrate (2), although it is conceivable that only a part of the metal substrate (2) is covered.

[0083] In the embodiment shown in Figure 1, the film (4) comprises two layers (4a, 4b).

[0084] Step iv The metal substrate (2) and the metal mesh (3) from step (ii) are heated in step (iv) prior to steps (v) and (vi) of the method. The metal substrate (2) and the metal mesh (3) can be heated by any suitable device, for example in a furnace or by induction.

[0085] Step v Before the bonding in step vi, the film (4) is placed on the metal substrate (2), and its layer (4a) faces the surface (2a) of the metal substrate (2) and the metal mesh (3) that was previously heated in step iii.

[0086] During the bonding step vi, the film (4) is arranged such that the entire surface of the layer (4a) simultaneously contacts the surface of the surface (2a) of the metal substrate (2) and the metal mesh (3).

[0087] To ensure this contact, the film (4) is attached to the upper tool or stretched between two rollers.

[0088] Step vi When the metal substrate (2) and the metal mesh (3) are bonded to the film (4) by hot stamping, the metal substrate (2) and the metal mesh (3) are at a temperature higher than the lowest of the melting point of the semi-crystalline thermoplastic polymer of the layer (4a) and the glass transition temperature (Tg) of the amorphous thermoplastic polymer during bonding.

[0089] If the temperature during bonding is lower than the lowest of the melting point of the semi-crystalline thermoplastic polymer of the layer (4a) and the glass transition temperature (Tg) of the amorphous thermoplastic polymer, the adhesion of the film (4) to the metal substrate (2) and the metal mesh (3) will be insufficient.

[0090] When the temperature is higher than 550 °C, deterioration of the film (4) is observed.

[0091] When the layer (4a) mainly contains PTFE by weight among the semi-crystalline or amorphous thermoplastic polymers constituting it, the metal substrate (2) and the metal mesh (3) are formed between 350 °C and 550 °C, preferably between 400 °C and 450 °C, during bonding with the film (4).

[0092] The temperature of the metal substrate (2) and the metal mesh (3) during bonding corresponds to the temperature of the metal substrate (2) and the metal mesh (3) when stamping starts, i.e., when the pressing of the set of the metal substrate (2) and the metal mesh (3) / film (4) starts.

[0093] According to one embodiment, the bonding by hot stamping in step vi. is performed by a hydraulic or mechanical press comprising a lower tool and an upper tool, between which the metal substrate (2) and the metal mesh (3) are bonded to the film (4), the metal substrate (2) preferentially contacts the lower tool, and the film (4) preferentially contacts the upper tool.

[0094] The surface of the lower tool is preferably flat and can be surface-treated to avoid any adhesion of the metal substrate to the tool.

[0095] Preferably, the plane of the surface of the upper tool has an angle configured between 0.01 degrees and 0.5 degrees, preferably between 0.15 degrees and 0.25 degrees, with respect to the plane of the surface of the lower tool. This angle makes it possible to limit the entrapment of air during the bonding step.

[0096] Preferably, before bonding step v., the bonding tool is not heated.

[0097] Optionally, the lower tool can be heated. Optionally, the upper tool can be cooled.

[0098] According to one embodiment, the lower tool is heated to a temperature configured between 25°C and the temperature of the metal substrate (2) during bonding, and / or the upper tool is brought to a temperature configured between 15°C and 120°C during step vi.

[0099] Unless otherwise specified, the temperature values shown in this application correspond to the measured temperature values, not the set temperatures.

[0100] The temperature value is measured by any suitable means, for example, a temperature probe disposed within the surface or thickness of an element being heated or cooled.

[0101] The temperature of the metal substrate (2) and the metal mesh (3) during bonding corresponds to the temperature of the surface (2a) of the metal substrate (2) when the pressing of the set of the metal substrate (2) and the metal mesh (3) / film (4) begins.

[0102] The temperature of the metal substrate (2) and the metal mesh (3) can then decrease during the stamping operation, especially if the lower tool is not heated prior to the bonding step.

[0103] During the stamping operation of step vi, a pressure of 100 MPa or more, preferably several hundred MPa, is advantageously used.

[0104] According to one embodiment, the metal substrate (2), the metal mesh (3), and the film (4) are maintained under a pressure configured between 100 MPa and 800 MPa, preferably between 350 MPa and 500 MPa, during step vi.

[0105] The pressure applied during the stamping operation is considerably higher than the pressure applied in conventional metal substrate / polymer film bonding methods, such as hot pressing, which is only a few MPa.

[0106] According to one embodiment, the time for maintaining the metal substrate (2), the metal mesh (3), and the film (4) under pressure during step vi is 1 minute or less, preferably 15 seconds or less.

[0107] Stamping can be performed by applying a sharp blow for a time of less than 5 seconds.

[0108] According to another embodiment, the time for maintaining the metal substrate (2), the metal mesh (3), and the film (4) under pressure is configured between 1 second and 1 minute, preferably between 2 seconds and 15 seconds, during step vi.

[0109] When the film (4) comes into contact with the heated metal substrate (2) and the heated metal mesh (3) during bonding, it is essentially heated by conduction. Subsequently, it is cooled during stamping due to the thermal inertia of the bonding tool, which has a lower temperature than the heating temperature of the metal substrate (2). Therefore, especially when the lower tool is not heated before the bonding step, the temperature of the film (4) can drop rapidly during the stamping operation.

[0110] The film (4) is preferably not heated before the bonding step vi.

[0111] Therefore, according to the method of the present invention, the film (4) can be heated to a temperature exceeding the lowest of the melting point of the semi-crystalline thermoplastic polymer of the layer (4a) and the glass transition temperature (Tg) of the amorphous thermoplastic polymer, very locally, especially at the interface between the metal substrate (2) and the film (4), for a very short time, which does not cause any deterioration of the film (4).

[0112] Advantageously, at the end of the step vi of bonding the film (4) to the metal substrate (2) and the mesh (3), i.e., when the combination of the film (4), the metal substrate (2), and the mesh (3) is no longer under pressure, the temperature of the film (4) is lower than the lowest of the melting point of the semi-crystalline thermoplastic polymer of the layer (4a) and the glass transition temperature (Tg) of the amorphous thermoplastic polymer.

[0113] During bonding by stamping, the above-mentioned combination of temperature and pressure makes it possible to ensure the adhesion of the film (4) on the metal substrate (2) and the metal mesh (3) in a very short time.

[0114] In step ii, the metal mesh (3) is attached to the surface (2a) by attachment points or at least partially embedded in the surface of the metal substrate (2).

[0115] The step vi of joining the metal substrate (2) and the metal mesh (3) to the film (4) by hot stamping can also lead to partially embedding the metal mesh (3) in the surface of the metal substrate (2).

[0116] The presence of the metal mesh (3) helps to improve the performance of the non-stick cooking surface, in particular by enhancing the resistance of the non-stick coating to scratches.

[0117] The metal mesh (3) can serve to limit the penetration of the non-stick coating of the metal tool and thus limit the formation of scratches.

[0118] Due to the presence of the metal mesh (2), the cooking surface (5) of the coated cooking body (1) can also have a surface texture, for example, in the form of reliefs.

[0119] These reliefs, especially when using a metal tool, can enable the metal tool to mainly contact the peaks of the reliefs on the cooking surface (5) and enhance the resistance of the non-stick coating to scratches.

[0120] FIG. 4 shows a cross-sectional view of an exemplary embodiment of a coated cooking body (1) according to the invention, purely for illustrative and non-limiting purposes, including a metal substrate (2), a metal mesh (3), and a film (4).

[0121] In FIG. 4a, the metal mesh (3) is fully crimped to the metal substrate (2).

[0122] In FIG. 4b, the metal mesh (3) is only partially crimped to the metal substrate (2), and the surface of the metal mesh (3) appears on the surface of the film (4), i.e., the film (4) does not cover the entire metal mesh (3).

[0123] In FIG. 4c, the metal mesh (3) is only partially crimped to the metal substrate (2), and the surface of the metal mesh (3) is completely covered by the film (4).

[0124] According to a modification not shown, the metal mesh (3) is only partially crimped to the metal substrate (2), and the surface of the metal mesh (3) is completely covered by the film (4). The surface of the film (4) after bonding is not flat due to the presence of the metal mesh and has a relief in the form of protrusions.

[0125] The coated cooking body (1) may also have a configuration of bonding of the metal substrate (2), the metal mesh (3), and the film (4) that is not the same in different regions of the coated cooking body (1). Thus, the metal mesh (3) may be completely crimped to the metal substrate (2) in some regions of the coated cooking body (1) and partially crimped to the metal substrate (2) in other regions of the coated cooking body (1).

[0126] After bonding, the metal substrate (2) and the metal mesh (3) coated with the film (4) are left to cool to room temperature in order to obtain maximum adhesion between the metal substrate (2), the metal mesh (3), and the film (4).

[0127] Thereafter, the metal substrate (2) coated with the film (4) can be shaped at the end of step (vi).

[0128] Accordingly, a second object of the present invention relates to a method of shaping a coated cooking body as described above, including a step (a) of press-forming the coated cooking body (1) obtained at the end of step (vi).

[0129] The shaping method may further include a step (b) of stretching the coated cooking body (1) obtained at the end of step (a).

[0130] The adhesion of the film (4) to the metal substrate (2) before shaping must be sufficiently good so as to avoid any loss of adhesion during and after the shaping operation.

[0131] The coated cooking body (1) according to the method of the present invention can form a cooking container of cooking utensils, which is selected from the group consisting of a sauce pan, a frying pan, a skillet, a fondue or raclette pan, a stew pot, a Chinese wok, a sauté pan, a crepe pan, a grill, a griddle, a cooking pot, a cocotte, a cooking mold.

[0132] The coated cooking body (1) according to the method of the present invention can form a cooking container of electric cooking utensils, which is selected from the group consisting of an electric crepe maker, an electric raclette appliance, an electric fondue appliance, an electric grill, an electric griddle, an electric cooker, a cooking robot, a bread maker. Therefore, the cooking utensils can form cooking accessories for electric cooking utensils.

Claims

1. A method for manufacturing a coated cooking body (1), the manufacturing method comprising: i. preparing a metal substrate (2) and a metal mesh (3), wherein the metal substrate (2) has a surface (2a) intended to be brought into contact with the metal mesh (3), the step of preparing the metal substrate (2) and the metal mesh (3); ii. attaching the metal mesh (3) to the surface (2a) of the metal substrate (2); iii. preparing a film (4), wherein the film (4) comprises a layer (4a) containing one or more semi-crystalline or amorphous thermoplastic polymers, the layer (4a) being intended to be brought into contact with the surface (2a) of the metal substrate (2) and the metal mesh (3), the step of preparing the film (4); iv. heating the metal substrate (2) and the metal mesh (3); v. disposing the film (4) such that the layer (4a) faces the surface (2a) of the metal substrate (2) and the metal mesh (3) heated in step iv; vi. bonding the metal substrate (2) and the metal mesh (3) to the film (4) by hot stamping, wherein the metal substrate (2) and the metal mesh (3) are at a temperature higher than the lowest of the melting point of the semi-crystalline thermoplastic polymer and the glass transition temperature (Tg) of the amorphous thermoplastic polymer of the layer (4a) during bonding, the step of bonding, characterized in that it comprises a method for manufacturing a coated cooking body (1).

2. The method for manufacturing a coated cooking body (1) according to claim 1, wherein the bonding by hot stamping in step vi is performed by a hydraulic or mechanical press comprising a lower tool and an upper tool, and between the lower tool and the upper tool, the metal substrate (2) and the metal mesh (3) are bonded to the film (4), the metal substrate (2) preferably being in contact with the lower tool, and the film (4) preferably being in contact with the upper tool, characterized in that it is a method for manufacturing a coated cooking body (1).

3. A method for manufacturing the coated cooking body (1) according to claim 2, wherein in the step vi, the metal substrate (2), the metal mesh (3), and the film (4) are maintained under a pressure configured between 100 MPa and 800 MPa, preferably between 350 MPa and 500 MPa. A method for manufacturing the coated cooking body (1).

4. A method for manufacturing the coated cooking body (1) according to claim 2 or 3, wherein in the step vi, the duration of maintaining the metal substrate (2), the metal mesh (3), and the film (4) under pressure is 1 minute or less, preferably 15 seconds or less. A method for manufacturing the coated cooking body (1).

5. A method for manufacturing the coated cooking utensil according to any one of claims 2 to 4, wherein in the step vi, the duration of maintaining the metal substrate (2), the metal mesh (3), and the film (4) under pressure is configured between 1 second and 1 minute, preferably between 2 seconds and 15 seconds. A method for manufacturing the coated cooking utensil.

6. A method for manufacturing the coated cooking body (1) according to any one of claims 2 to 5, wherein the plane of the surface of the upper tool has an angle configured between 0.01 degrees and 0.5 degrees, preferably between 0.15 degrees and 0.25 degrees, with respect to the plane of the surface of the lower tool. A method for manufacturing the coated cooking body (1).

7. A method for manufacturing the coated cooking body (1) according to any one of claims 2 to 6, wherein in the step vi, the lower tool is heated to a temperature configured between 25°C and the temperature of the metal substrate (2) during bonding, and / or the upper tool is brought to a temperature configured between 15°C and 120°C. A method for manufacturing the coated cooking body (1).

8. A method for manufacturing the coated cooking body (1) according to any one of claims 1 to 7, wherein the metal substrate (2) is an aluminum substrate, a stainless steel substrate, or a multilayer metal substrate whose surface (2a) is made of an aluminum alloy or stainless steel. A method for manufacturing the coated cooking body (1).

9. A method for manufacturing the coated cooking body (1) according to any one of claims 1 to 8, wherein the surface of the surface (2a) of the metal substrate (2) is subjected to a surface treatment, and the surface treatment is chemical corrosion, brushing, hydration, sandblasting, shot peening, plasma or corona or laser type physicochemical treatment, chemical activation, or a combination of these different techniques. A method for manufacturing a coated cooking body (1).

10. A method for manufacturing the coated cooking body (1) according to any one of claims 1 to 9, wherein the metal mesh (3) is a woven metal mesh or an expanded metal mesh, preferably made of stainless steel. A method for manufacturing a coated cooking body (1).

11. A method for manufacturing the coated cooking body (1) according to any one of claims 1 to 10, wherein the metal mesh (3) has a thickness configured between 50 μm and 800 μm. A method for manufacturing a coated cooking body (1).

12. A method for manufacturing the coated cooking body (1) according to any one of claims 1 to 11, wherein the attachment of the metal mesh (3) to the surface (2a) of the metal substrate (2) is obtained by die pressing, and the metal mesh (3) is at least partially embedded in the surface (2a). A method for manufacturing a coated cooking body (1).

13. A method for manufacturing the coated cooking body (1) according to any one of claims 1 to 12, wherein the film (4) comprises a single layer (4a) forming a cooking surface (5) and containing one or more semi-crystalline or amorphous thermoplastic polymers. A method for manufacturing a coated cooking body (1).

14. A method for manufacturing the coated cooking body (1) according to any one of claims 1 to 12, wherein the film (4) further comprises one or more layers, each containing one or more semi-crystalline or amorphous thermoplastic polymers. A method for manufacturing a coated cooking body (1).

15. A method for manufacturing the coated cooking body (1) according to any one of claims 1 to 14, wherein the layer (4a), and optionally one or more additional layers of the same or different semi-crystalline or amorphous thermoplastic polymers of the film (4) are, - Polytetrafluoroethylene (PTFE), tetrafluoroethylene and perfluoropropyl vinyl ether (PFA) copolymer, tetrafluoroethylene and hexafluoropropene (FEP) copolymer, polyvinylidene fluoride (PVDF), tetrafluoroethylene and polymethyl vinyl ether (MVA) copolymer, tetrafluoroethylene terpolymer, polymethyl vinyl ether and fluoroalkyl vinyl ether (TFE / PMVE / FAVE), ethylene tetrafluoroethylene (ETFE), and mixtures thereof, - 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) - containing polyaryl ether ketone (PAEK), - Poly(phenylene oxide) (PPO), polyether sulfone (PES), poly(phenylene ether sulfone) (PPSU) - containing poly(aryl ether sulfone) polymer (PAES), polyphenylene sulfide (PPS) - containing poly(arylene sulfide) (PAS), liquid crystal polymer, - Polyamideimide (PAI), polyimide (PI), polyetherimide (PEI), polybenzimidazole (PBI), - And a method for manufacturing the coated cooking body (1), characterized in that it is selected from the group consisting of mixtures thereof.

16. A method for manufacturing the coated cooking body (1) according to any one of claims 1 to 15, wherein the film (4) further comprises at least one filler and / or at least one reinforcing material. A method for manufacturing the coated cooking body (1), characterized by this.

17. A method for manufacturing the coated cooking body (1) according to any one of claims 1 to 16, wherein during the step (vi), the surface (2a) of the metal substrate (2) and the surface (4a) of the film (4) in contact with the metal mesh (3) are subjected to mechanical or chemical surface treatment. A method for manufacturing the coated cooking body (1).

18. A method for manufacturing the coated cooking body (1) according to any one of claims 1 to 17, wherein the thickness of the film (4) is between 5 μm and 500 μm, preferably between 25 μm and 150 μm. A method for manufacturing the coated cooking body (1).

19. A method for manufacturing the coated cooking body (1) according to any one of claims 1 to 18, comprising a step (a) of press-forming the coated cooking body (1) obtained at the end of the step (vi). A method for manufacturing the coated cooking body (1).

20. A method for manufacturing the coated cooking body (1) according to claim 19, further comprising a step (b) of stretching the coated cooking body (1) obtained at the end of the step (a). A method for manufacturing the coated cooking body (1).

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