The present invention relates to a coated non-electric substrate, a method for the manufacture of this coated non-electric substrate and a method for heating the coated non-electric substrate. It is particularly well suited for construction field, especially in real estate field, aeronautic, car industry and nautical industry.

It is known to use conventional heating systems to warm a room. It is also known to use a heating system in a car or in a plane to warm the indoor atmosphere. Usually, an electric heating system or a gas heating system are used. However, these systems are usually expensive and unattractive. Moreover, these systems take a lot of space. Finally, gas heating systems are the origin of a large proportion of CO2 omission, especially in urban environments.

The purpose of the invention is to provide a cheap and efficient heating system which allow to spread out the source of the heat to large surface that can be used notably in real estate field, in aeronautic field, in car industry and in nautical industry. Moreover, the object of the invention is to provide a heating system which is space saving.

This is achieved by providing a heating system according to claim 1 . The coated steel substrate can also comprise any characteristic of claims 2 to 15.

The invention also covers a method for the manufacture of the heating system according to claims 16 to 23.

The invention also covers a method for heating the heating system according to claim 24.

Finally, the invention also covers the use of the heating system according to claim 25.

The following terms are defined:

- Sheet resistance is a common electrical property used to characterize thin films of conducting and semiconducting materials. It is a measure of the lateral resistance through a thin square of material, i.e. the resistance between opposite sides of a square,

- Four Probe Method is employed when the sample is in the form of a thin wafer, such as a thin semiconductor material deposited on a substrate. It consists of four probes arranged linearly in a straight line at equal distance from each other. A constant current is passed through the two end probes and the potential drop V across the middle two probes is measured. An oven is provided with a heater to heat the sample so that behavior of the sample is studied with increase in temperature.

To illustrate the invention, various embodiments and trials of non-limiting examples will be described, particularly with reference to the following figures:

- Figure 1 illustrates a front view of a heating system according to the present invention.

- Figure 2 illustrates an exploded view of a heating system according to the present invention.

- Figure 3 illustrates an exploded view of a heating system according to a variant of the present invention.

- Figure 4 illustrates a first pattern of the heating coating according to the present invention.

- Figure 5 illustrates a second pattern of the heating coating according to the present invention.

- Figure 6 illustrates an example of at least one element chosen from kish- graphite, graphite and nanographite according to the present invention.

Other characteristics and advantages of the invention will become apparent from the following detailed description of the invention.

The invention relates to a heating system comprising in the following order: a) A first electrical insulator substrate, b) A combination of at least a first electrode, a second electrode and a heating coating comprising at least one element chosen from kish- graphite, graphite and nanographite; the heating coating not comprising : carbon nanotubes, iron, zinc, aluminum, magnesium, manganese, copper, nickel or an alloy containing one or more of these metals, metal halide, cuprous chloride, metal sulfate, acetate or carbonate and wherein: o The first electrode is arranged on the first electrical insulator substrate, o The heating coating covers at least partially the first electrode and is in contact with the second electrode so that the first electrode and the second electrode are electrically connected through the heating coating, c) A second electrical insulator film.

Without willing to be bound by any theory, it seems that the heating system according to the present invention acts like a heater. Indeed, it is believed that the heating coating has a low sheet resistance. Thus, when an electric voltage is applied on the at least two electrodes, an electric current goes through the electrodes and the heating system starts to release heat, the heating power being very high. Moreover, independent heating systems are not needed anymore. Indeed, the heating system can be included in the structure of houses, cars, etc. by sticking it on the walls or the floors.

Moreover, it seems that if the heating coating comprises at least one of the elements chosen from among: carbon nanotubes, iron, zinc, aluminum, magnesium, manganese, copper, nickel or an alloy containing one or more of these metals, metal halide, cuprous chloride, metal sulfate, acetate and carbonate; there is a risk that these elements affect the sheet resistance of the coating leading to a poor heater quality. Finally, the coated non-electric substrate according to the present invention is cheap and does not take space anymore.

Figure 1 illustrates an example of a heating system according to the present invention. In this example, the first electrical insulator substrate 1 is coated with a first electrode 2, a second electrode 2’, a heating coating 3 comprising at least one element chosen from kish-graphite, graphite and nanographite and a second electrical insulator film 4. Figure 2 illustrates the exploded view of this heating system according to the present invention.

Preferably, the first electrical insulator substrate 1 is made of a polymeric film comprising for example polyvinyl chloride (PVC), polypropylene, polyethylene terephthalate (PET), polyvinyl fluoride (PVF), polyphenylene ether (PPE), Polyester, ethylene-vinyl acetate (EVA), Tedlar®/PET/EVA (TPE) or Tedlar@/Polyester/Tedlar® (TPT) or other combinations thereof. It is preferably flexible. Preferably, the first electrical insulator substrate is coated with an adhesive underneath, i.e. on the opposite side of the heating coating. In this case, the heating system can be glued on a structure.

Preferably, the at least two electrodes are made of copper, silver, aluminum, steel or graphite.

According to one variant, the first and second electrodes are positioned side by side on the first electrical insulator substrate 1 . The gap between them strongly depends on the use of the heating system. Preferably the gap is comprised between 5 and 100 cm. Preferably, the two electrodes are in the form of ribbons. The heating coating 3 covers at least partially each of the two electrodes 2, 2’. Therefore, the electrical connection between the electrodes and the heating coating is made. In other words, electricity can go from the first electrode to the second electrode through the heating coating. According to the variant illustrated on Figure 2, the heating coating 3 is a one-piece coating covering the two electrodes in full. According to the variant illustrated on Figure 3, the heating coating is made of several ribbons transversally applied over the electrodes. Other possible patternings of the heating coating are illustrated on Figures 4 and 5. The heating system can notably comprise more than two electrodes.

According to another variant, the first electrode 2 is arranged on the first electrical insulator substrate. Preferably, the first electrode is in the form of a ribbon. The heating coating 3 covers at least partially the first electrode. It can be, for example, in the form of a ribbon, of several ribbons or of a large surface. The second electrode 2’ then covers at least partially the heating coating so that the electrical connection between the electrodes and the heating coating is made. Flere again, other patternings of the heating system are possible. The heating system can notably comprise more than two electrodes.

Preferably, the at least one element chosen from kish-graphite, graphite and nanographite has a form of nanoplatelet. Figure 6 illustrates an example of the element according to the present invention. In this example, the lateral size means the highest length of the element through the X axis and the thickness means the height of the element through the Z axis. The width of the element is illustrated through the Y axis. Advantageously, the heating coating comprises at least one element chosen from kish-graphite, graphite and nanographite having a lateral size between 1 .5 and 50pm and more preferably between 1 .5 and 20pm.

Preferably, the width size of the at least one element chosen from kish- graphite, graphite and nanographite is between 1.2 and 20pm.

Advantageously, the thickness of the at least one element chosen from kish- graphite, graphite and nanographite is between 60 and 90 nm.

Preferably, the heating coating further comprises binders including sodium carboxymethyl cellulose (NaCMC) and sodium polyacrylate (PaNa). Indeed, it is believed that the presence of these binders further improves the coating adhesion.

Preferably, NaCMC has a molecular weight between 90000 and 700000g.mol ¹ .

Preferably, the heating coating further comprises a surfactant including sodium deoxycholate (SDC). Without willing to be bound by any theory, it is believed that this surfactant further leads to a homogeneous coating.

Advantageously, in the heating coating, the at least one element chosen from kish-graphite, graphite and nanographite comprises above 95% by weight of C and more preferably above 99wt.%.

Preferably, the heating coating comprises above 70% by weight of C. More preferably, it comprises above 70% by weight of C, between 1 and 20% by weight of O, between 0.1 and 10% by weight of H and between 0.1 and 10% by weight of Na.

Preferably, the heating coating has a sheet resistance between 1 and 200 W/sq, preferably between 10 and 50 W/sq. Without willing to be bound by any theory, it is believed that this sheet resistance allows for an improvement of the released heat.

Preferably, the thickness of the heating coating is between 5 and 200pm, preferably between 10 and 75 pm.

The second electrical insulator film 4 is preferably made of an epoxy resin, polyacrylates, a polyester resin, a polyurethane resin, non-conductive polymers or other kind of solvent base resins or a mixture thereof. In a variant, the second electrical insulator film is made of a polymeric film comprising polyvinyl chloride (PVC), polypropylene, polyethylene terephthalate (PET), polyvinyl fluoride (PVF), polyphenylene ether (PPE), polyester or ethylene-vinyl acetate (EVA) or a combination thereof.

The second electrical insulator film 4 isolates the user of the heating system from the electrical part of the heating system. Accordingly, it preferably covers the at least two electrodes and the heating coating. According to one variant of the invention, the second electrical insulator film covers the first electrical insulator substrate in full.

Optionally, the heating system can comprise additional layers above the second electrical insulator film such as for example a thermochromic layer. Such layer can notably consist in a water-based ink containing thermochromic microcapsules so that the layer changes color once the temperature reaches the range of the thermochromic microcapsules. It can be applied by spray at 200- 500g/m ² .

The invention also relates to a method for the manufacture of the heating system according to the present invention, comprising the successive following steps:

A. The provision of a first electrical insulator substrate 1 ,

B. The deposition, on the first electrical insulator substrate, of a combination of at least a first electrode 2, a second electrode 2’ and a heating coating 3 comprising at least one element chosen from kish- graphite, graphite and nanographite; the coating not comprising : carbon nanotubes, iron, zinc, aluminum, magnesium, manganese, copper, nickel or an alloy containing one or more of these metals, metal halide, cuprous chloride, metal sulfate, acetate or carbonate and

C. The deposition of a second electrical insulator substrate film 4.

According to one variant, the step B) comprises the successive following sub steps:

- The deposition of the first electrode 2 and the second electrode 2’ on the first electrical insulator substrate,

- The deposition of the heating coating 3 on at least partially each of the first electrode and the second electrode. According to another variant, the step C) comprises the successive following sub-steps:

- The deposition of the first electrode 2 on the first electrical insulator substrate,

- The deposition of the heating coating 3 on at least partially the first electrode,

- The deposition of the second electrode 2’ on at least partially the heating coating.

Preferably, in step B), the deposition of the first and second electrodes 2,2’ is performed by printing, sticking, fused deposition or screen-printing.

Preferably, in step B), the heating coating comprising at least one element chosen from kish-graphite, graphite and nanographite is deposited by spraying, roll coating, brushing, printing or screen-printing.

Preferably, in step B), the heating coating is deposited using an aqueous- based solution comprising at least one element chosen from kish-graphite, graphite and nanographite. More preferably, the concentration of the at least one element chosen from kish-graphite, graphite and nanographite in the aqueous-based solution is between 5.0wt.% and 20.0wt.%. Without willing to be bound by any theory, it is believed that this concentration further improve the texture of the coating.

Preferably, the aqueous-based solution further comprises binders including sodium carboxymethyl cellulose (NaCMC) and sodium polyacrylate (PaNa). It is believed that the presence of these binders further improves the viscosity of the solution leading to a better coating adhesion. More preferably, the concentration of carboxymethyl cellulose (NaCMC) and sodium polyacrylate (PaNa) independently from each other in the solution is between 0.05wt.% and 10wt.%. Without willing to be bound by any theory, it is believed that these concentrations further improve the sheet resistance of the heating coating leading to a better heating.

Preferably, the aqueous-based solution further comprises a surfactant including sodium deoxycholate (SDC). Without willing to be bound by any theory, it is believed that this surfactant further leads to a homogeneous solution and thus to a homogeneous coating. More preferably, the concentration of the surfactant in the solution is between 0.05wt.% and 10wt.%. Preferably, the aqueous-based solution comprises above 10% by weight of C, between 40 and 80% by weight of O, between 5 and 15% by weight of H and between 0.1 and 5% by weight of Na.

Preferably, the viscosity is between 10 and 20 Pa-s.

In a preferred embodiment, the heating coating is dried after step B). Without willing to be bound by any theory, it is believed that the drying step allows for an improvement of the coating adhesion. Indeed, since water evaporates, the binder becomes tackier and more viscous leading to a hardened condition. In a preferred embodiment, the drying is performed at room temperature or a temperature between 50 and 150°C and preferably between 80 and 120°C.

In another preferred embodiment, no drying step is performed.

Preferably, when a drying is applied, the drying step is performed with hot air.

Advantageously, when a drying is applied, the drying is performed during 5 to 60 minutes and for example, between 15 and 30 minutes.

Preferably, in step C), the deposition of the second electrical insulator film is performed by spraying, roll-coating, brushing, printing or screen-printing.

The invention also relates to a method for heating the heating system according to the present invention comprising: a) The application of an electric voltage through the first and second electrodes of the heating system.

Preferably, the electric voltage is between 0.5 and 50Volts in directional current (DC) or between 110 and 230volts in alternative courant (AC).

Finally, the invention relates to the use of a heating system according to the present invention for the manufacture of heating wall, underfloor heating or textile.

The invention will now be explained in trials carried out for information only. They are not limiting.

Examples:

For Trials 1 and 2, an electrical insulator substrate being a PVC was used.

Then, two copper electrodes were located side by side on the flexible PVC substrate with a gap of 10 cm. For trial 1 , such substrate was then coated by screen-printing an aqueous solution comprising 9 wt.% of kish graphite, 0.6 wt.% of sodium carboxymethyl cellulose (NaCMC), 0.4 wt.% of sodium polyacrylate (PaNa) and 0.9 wt.% of sodium deoxycholate (SDC). Kish graphite was in the form of nanoplatelets having a lateral size between 1.5 and 50pm, a width between 1.2 and 20 pm and a height between 60 and 90nm. The viscosity of the aqueous solution was of 40 Pa.s. Then, the coating was dried with hot air during 20 minutes at 100°C.

For trial 2, the PVC substrate was then coated by printing an aqueous solution comprising 2.9 wt.% of reduced graphene oxide having a lateral size between 25 and 30pm, a width lower than 30 pm and a height between 2-5nm; 1.4 wt.% of sodium carboxymethyl cellulose (NaCMC) and 1.3 wt.% of sodium deoxycholate (SDC) onto the electrical insulator substrate. The viscosity of the aqueous solution was of 10 Pa.s. Then, the coating was dried with hot air during 15 minutes at 100°C. Both Trials were then coated with a second electrical insulator film being a covercoat L406/TFIIX® deposited by screen-printing.

An electric voltage of 46V was applied through the copper electrodes. The sheet resistance, the heating speed and the power density were determined by the four-probe method at room temperature, a system of thermocouples, a voltage source and a multimeter. The heating performance was also evaluated by naked eyes.

The results are in the following Table 1 :

^* : according to the present invention.

Trial 1 according to the present invention shows an excellent heating quality.