FR3057733A1 - USE AS A HEATING ELEMENT OF A CONDUCTIVE AND TRANSPARENT POLYMERIC FILM BASED ON POLY (THIO- OR SELENO-) PHENIC POLYMERS - Google Patents

Abstract

The present invention relates to the use, as a transparent heating element, especially in transparent conductive heating devices, of a conductive and transparent polymeric film formed of at least 70% by weight of one or more polymers. (S) poly (thio- or seleno-phen) s (s) in a form combined or not with one or more counter anion (s), said film not comprising a percolating network of ancillary electrically conductive materials. It also relates to a transparent conductive heating device comprising such a conductive and transparent polymeric film, and a method for preparing such a heating device.

Description

Holder (s): COMMISSION OF ATOMIC ENERGY AND ALTERNATIVE ENERGIES Public establishment, UNIVERSITE GRENOBLE ALPES Public establishment.

Extension request (s)

Agent (s): NONY CABINET.

USE AS A HEATING ELEMENT OF A CONDUCTIVE AND TRANSPARENT POLYMERIC FILM BASED ON POLY (THIO- OR SELENO-) PHENIC POLYMERS.

FR 3 057 733 - A1

The present invention relates to the use, as a transparent heating element, in particular in transparent conduction heating devices, of a conductive and transparent polymeric film formed to at least 70% by weight of one or more polymer (s) poly (thio- or seleno-) phenic (s) in a form combined or not with one or more counter-anion (s), said film not comprising a percolating network of ancillary electrically conductive materials.

It also relates to a transparent conduction heating device comprising such a conductive and transparent polymeric film, as well as to a process for the preparation of such a heating device.

i

The present invention relates to the use of a conductive and transparent polymeric film based on poly (thio- or selenophenic) polymers, as a heating element for Joule effect heating devices, for which a visibility requirement is required. .

Transparent conductive heating films are attracting increasing interest in a wide range of applications, for example for display devices, automobile demisting or defrosting systems, heated glazing, etc.

Currently, the techniques for manufacturing transparent heating films are based on the use of films of transparent conductive oxides (TCOs) and more particularly of tin-doped indium oxide (ITO).

However, the use of these materials has a certain number of drawbacks, in particular with regard to the high and fluctuating cost of indium and the great mechanical brittleness of ITO. Also, the manufacturing techniques for these films are complex, requiring to proceed under vacuum and limited to deposits on flat surfaces.

Recent advances in the field of nanotechnologies have made it possible to offer networks of nano-objects, in particular based on carbon nanomaterials (carbon nanotubes (CNT), graphene), metallic nanowires, in particular silver or copper, or even hybrid networks of nanowires associated with carbon nanotubes, graphene or a conductive polymer, making it possible to combine electrical conductivity and transparency properties (Gupta et al., ACS Appl. Mater. Interfaces, 2016, 8, 12559-12575 ).

However, these materials are not entirely satisfactory, in particular due to insufficient conductivity, too high a cost, a difficult or even expensive implementation, an insufficient visible transmittance and / or d '' too low a mechanical resistance.

In fact, the properties which condition good compatibility of a conductive material for use as a heating material are low surface resistance and high thermal stability. However, in the context of the present invention, these two properties must also be associated with a high transmittance in the visible range and good mechanical properties, compatible in particular with a certain flexibility or deformability of the heating material, in particular for applications in optical systems such as helmet visors or ski goggles.

There therefore remains a need for transparent heating elements capable of meeting all of these expectations.

The present invention aims precisely to meet this need.

More specifically, the present invention relates, according to a first of its aspects, the use as a transparent heating element, in particular in transparent conduction heating devices, of a conductive and transparent polymer film formed at least 70% by weight of one or more poly (thio- or selenophenic) polymers in a form combined or not with one or more counter anions, said film not comprising a percolating network of annexed electrically conductive materials.

The conductive and transparent polymeric film according to the invention will more simply be designated, in the remainder of the text, under the name "transparent heating film".

By “percolating network of ancillary electrically conductive materials”, it is intended to denote electrically conductive materials, such as nanowires, present in the form of a network so that the current can percolate over the whole of the layer thus formed.

The present invention relates more particularly to the use, as a transparent heating element, in particular in transparent conduction heating devices, of a conductive and transparent polymer film formed at least 70% by weight of one or more poly polymers. (thio- or seleno-) phenics in a form combined or not with one or more counter anions, said film being free of electrically conductive ancillary materials.

By “free of annexed electrically conductive materials”, it is meant to mean that the polymeric film according to the invention does not comprise (in other words, is devoid / devoid of) electrically conductive entities, distinct from poly (thioou seleno) phenic polymers, conventionally used for their electrical conductivity properties in conductive heating films, such as for example metallic nanoparticles, carbon nanotubes (CNT), metallic nanowires, in particular silver or copper, graphene sheets, etc. ..

In fact, the heating film according to the invention is distinct from so-called "hydride" films which combine at least two electrically conductive materials.

The invention more particularly uses, as a transparent heating element, a single polymeric film (or single layer) formed to at least 70% by weight of one or more poly (thio- or seleno-) phenic polymers under a form whether or not combined with one or more counter anions, said film not comprising a percolating network of annexed electrically conductive materials, preferably being free of annexed electrically conductive materials.

According to a particularly preferred embodiment, the transparent heating film according to the invention is formed exclusively from poly (thio- or seleno-) phenic polymer (s) associated or not with one or more counter anions.

According to a particular embodiment, the poly (thio- or seleno-) phenic polymer used is poly (3,4-ethylenedioxythiophene), commonly called PEDOT.

To the knowledge of the inventors, poly (thio- or selenophenic) conductive polymers have never been used to form, on their own, in the absence of annexed electrically conductive materials such as metallic nanowires, a film transparent heater as a Joule effect heating element, in particular intended for heating, defrosting and / or demisting devices.

In fact, polymers of poly (thio- or seleno-) phenic type, such as PEDOT, are usually used for their high electrical conductivity (σ> 500 S / cm) in the fields of organic electronics, organic photovoltaics and organic thermoelectricity. PEDOT is systematically combined with a counterion, usually sodium poly (styrene sulfonate) (PSS), p-toluene sulfonate also called tosylate (Tos) or trifluoromethylsulfonate also called triflate (OTf). These materials have the advantage of being easily implemented by low-cost printing techniques, for example by screen printing, ink jet deposition, spray coating (“spray-coating” in English), coating by slot (“slot-die” in English) or liquid flow coating (“flow-coating” in English).

Against all expectations, the inventors have found that it is possible to form, from these conductive poly (thio- or seleno-) polymers, combined or not with counter anions, polymer films with electrical conductivity sufficient to allow efficient heating by Joule effect, while remaining transparent.

The Joule effect is a heat producing effect which occurs when electric current passes through a conductor with resistance. It manifests as an increase in the thermal energy of the conductor and its temperature.

In the remainder of the text, we will designate a film or element dedicated to providing Joule heating under the term "heating" film or element.

The implementation, as a heating element, of a conductive and transparent polymeric film based on poly (thio- or selenophenic) polymer according to the invention proves to be advantageous in several respects.

First, a film based on poly (thio- or seleno-) phenic polymer advantageously combines good heating performance and transparency.

In particular, a polymeric film according to the invention has a surface resistance less than or equal to 500 ohm / square, in particular less than or equal to 300 ohm / square, preferably less than or equal to 150 ohm / square and more preferably less than or equal at 100 ohm / square.

It also has a transmittance, over the entire visible spectrum, of greater than or equal to 70%, in particular greater than or equal to 80% and more particularly greater than or equal to 85%.

Furthermore, compared to hybrid conductive films, the polymeric film according to the invention, in particular formed exclusively from poly (thio- or seleno-) phenic polymer (s) according to the invention, has improved stability. In fact, there is no possible reaction (for example redox or acid-base reaction) between the different constituents of the mixture. Also, the polymeric films according to the invention are easier to process, do not require the use of metals, and their cost is lower.

A polymeric film according to the invention can advantageously be used, as a transparent heating element, in an optical heating device.

Thus, according to another of its aspects, the present invention relates to a transparent conduction heating device, comprising at least:

- a substrate having a transmittance, over the entire visible spectrum, of at least 70%;

- as a transparent heating element, a conductive and transparent polymer film, formed at least 70% by weight of one or more poly (thio- or seleno-) phenic polymers in a form combined or not with one or more against anions, and not comprising a percolating network of ancillary electrically conductive materials, preferably being free of ancillary electrically conductive materials, said film being supported by the substrate; and

- contact recovery electrodes.

Preferably, the conductive and transparent polymeric film according to the invention is used, as a single heating element (in other words dedicated to providing heating by Joule effect), in a transparent heating device according to the invention.

In other words, the transparent heating element is formed of a single film (or single layer) based on poly (thio- or selenophenic) polymer (s) in a form combined or not with one or more against anion (s) and not comprising a percolating network of annexed electrically conductive materials, preferably being free of annexed electrically conductive materials.

In particular, the polymeric film according to the invention is not associated with one or more additional layers of additional electrically conductive materials, for example a layer of metallic nanowires.

Preferably, the transparent heating element is formed of a single film (or layer) formed only of one or more poly (thio- or selenophenic) polymer (s) in a form combined or not with a or more counter anion (s).

The heating device can also comprise a transparent encapsulation layer, as detailed in the text below.

Advantageously, the device according to the invention combines both heating and optical transparency properties, which makes it suitable for the design of various transparent heating, defrosting and / or demisting systems, for example for glazing. , shower panels, glasses, heating elements for optoelectronic devices, etc.

In particular, a heating device according to the invention is compatible with use in a temperature range between 1 ° C and 250 ° C, in particular between 2 and 50 ° C.

Furthermore, a transparent heating device according to the invention advantageously has an overall transmittance, over the entire visible spectrum, of at least 70%, in particular at least 80%.

Finally, the polymer films, used as transparent heating elements according to the invention, are mechanically resistant and compatible with application on flexible and / or non-planar substrates, and therefore suitable for applications where flexibility or deformability of the transparent heating device are sought, for example for heating vision devices, such as helmet visors or ski masks.

Finally, the production of transparent heating devices according to the invention is easy and advantageous in terms of cost. In particular, as detailed in the following text, the films based on poly (thio- or seleno-) phenic polymers can be formed on the surface of a substrate, by low-cost printing techniques such as, for example, screen printing. , inkjet, spray or slot coating.

The present invention relates, according to yet another of its aspects, to a process for preparing a transparent conduction heating device, in particular as defined above, comprising at least the steps consisting of:

(i) have a substrate having a transmittance, over the entire visible spectrum, of at least 70%;

(ii) forming, on all or part of the surface of at least one of the faces of said substrate, a conductive and transparent polymeric film as defined above; and (iii) establish contact recovery electrodes, step (iii) being carried out before or after the formation of said conductive and transparent polymeric film.

An encapsulation layer can be formed on the outer surface of said transparent conductive polymer film. It can be deposited before or after the formation of the contact recovery electrodes, in the case where these are established after the formation of the conductive and transparent polymer film.

Other characteristics, advantages and modes of application of the heating device according to the invention and of its preparation will emerge more clearly on reading the detailed description which follows, given by way of illustration and not limitation.

In the following text, the expressions "between ... and ...", "ranging from ... to ..." and "varying from ... to ..." are equivalent and are intended to mean that the terminals are included, unless otherwise stated.

Unless otherwise indicated, the expression "comprising / comprising a" must be understood as "comprising / comprising at least one".

CONDUCTIVE AND TRANSPARENT POLYMERIC FILM

As mentioned previously, the transparent conductive film according to the invention is based on polymer (s) of poly (thio- or seleno-) phenic type (s).

Preferably, the poly (thio- or selenophenic) polymer is used in a combined form with one or more counter anions.

The counter anions can more particularly be of the triflate, sulfonate, triflimidate, mesylate, perchlorate and hexafluorophosphate type.

In particular, they can be chosen from sodium poly (styrene sulfonate) (PSS), toluene sulfonate or tosylate (OTs), Triflate (OTf) and methylsulfonate (Ms).

According to a particularly preferred embodiment, the transparent conductive film according to the invention is based on a polymer of polythiophenic type.

The polythiophenic type polymer can more particularly be derived from the polymerization of monomer (s) chosen from thiophene, 3-alkylthiophenes, 3,4dialkylthiophenes, 3,4-cycloalkylthiophenes, 3,4-dialkoxythiophenes, and 3,4alkylenedioxythiophenes , in which the identical or different alkyl groups have the formula C _n H _2n + i with n between 1 and 12.

According to a preferred variant, the thiophenic polymer derives from the polymerization of monomer (s) chosen from 3,4-dialkylthiophenes, 3,4-cycloalkylthiophenes, 3,4dialkoxythiophenes, and 3,4-alkylenedioxythiophenes, in which the groups alkyls, identical or different, have the formula C _n H _2n + i with n between 1 and 12.

Thus, the thiophenic polymer can for example be:

a poly (3,4-dialkylthiophene) of formula:

a poly (3,4-cycloalkylthiophene) of formula:

a poly (3,4-dialkoxythiophene) of formula:

.p

I Ù / 7 jn ° ° T a poly (3,4-alkylenedioxythiophene) of formula:

^S *

Ly, ff i

Orv

In particular, the monomers are chosen from thiophene, 3,4ethylenedioxythiophene (EDOT), 3-hexylthiophene and 3,4-propylenedioxythiophene (PRODOT).

Preferably, the monomer is 3,4-ethylenedioxythiophene (EDOT).

Thus, according to a particular embodiment, the transparent conductive film according to the invention is based on poly (3,4-ethylenedioxythiophene) (PEDOT).

PEDOT is advantageously used in a form combined with a counterion, more particularly chosen from sodium poly (styrene sulfonate) (PSS), toluene sulfonate or tosylate (OTs), triflate (OTf) and methylsulfonate (Ms), in particular chosen from sodium poly (styrene sulfonate) (PSS), tosylate (OTs) and triflate (OTf).

According to a particular embodiment, the transparent conductive film according to the invention is based on PEDOT: PSS, PEDOT: OTf or PEDOT: OTs, in particular PEDOT: PSS or PEDOT: OTf.

Preferably, the transparent conductive film according to the invention is based on PEDOT: PSS.

PEDOT: PSS type polymers include:

- poly (3,4-EthyleneDiOxyThiophene) or PEDOT with chemical structure:

À 'fl 8 © l with n a positive integer; and PolyStyrene Sulphonate or PSS in protonated form (on the right) or not (on the left), of chemical structure:

T

O *

with x and y positive integers.

According to another alternative embodiment, the transparent conductive film according to the invention is based on a polyselenophenic type polymer.

The polyselenophenic type polymer can more particularly be derived from the polymerization of monomer (s) chosen from selenophene, 3,4dialkylselenophenes, 3,4-cycloalkylselenophenes, 3,4-dialkoxyselenophenes, and 3,4alkylenedioxyselenophenes, in which the alkyl groups, identical or different, have the formula C _n H _2n + i with n between 1 and 12.

The selenophenic polymer can for example be:

- a poly (3,4-dialkylselenophene) of formula:

j Γ »CH% ηΜ« n -b » ¹ * 2i *» * 1 ίο

a poly (3,4-cycloalkylselenophene) of formula:

! Se 1 ..

L \\ ff jn

- a poly (3,4-dialkoxyselenophene) of formula:

a poly (3,4-alkylenedioxyselenophene) of formula:

i ï

Se 't,' *

L \\ // Jn

O, O ’m

In particular, the monomers are chosen from selenophene, 3,4ethylenedioxyselenophene (EDOS), 3-hexyl selenophene, and 3,4propy 1 enedi oxy sel enophene (PRODO S).

In particular, the monomer can be 3,4-ethylenedioxyselenophene (EDOS).

Thus, according to a particular embodiment, the transparent conductive film according to the invention is based on poly (3,4-ethylenedioxyselenophene) (PEDOS).

Of course, other alternative embodiments of a film according to the invention can be envisaged, for example combining several polymers of the poly (thio- or seleno-) phenic type, in particular as defined above.

According to a particular embodiment, the polymeric film of the invention can comprise two distinct species of counter anion with at least one of them being an anionic form of a sulfurized acid.

According to a preferred embodiment, only one of the two species is an anionic form of a sulfurized acid, in particular chosen from sulfuric acid or any sulfonic acid.

Preferably, the sulfurized acid is sulfuric acid.

Thus, a conductive and transparent polymeric film according to the invention can contain at least hydrogen sulfate and triflate counter anions.

Preferably, the conductive and transparent polymer film, used as a transparent heating element according to the invention, is formed at least 80% by weight, and more particularly at least 90% by weight of polymer (s) poly (thio- or seleno-) phenic (s) in a form combined or not with one or more counter-anions.

In other words, the said poly (thio- or selenophenic) polymer (s), possibly combined with one or more counter anions, represent at least 70% by weight, in particular at least 80% by weight, preferably at minus 90% by weight, of the total weight of the heating film according to the invention.

Furthermore, as mentioned above, the transparent heating film according to the invention is devoid of additional electrically conductive materials, such as for example metallic nanoparticles, carbon nanotubes (CNT), metallic nanowires, graphene sheets, etc. .

Thus, according to a particularly preferred embodiment, the transparent heating film according to the invention is formed exclusively of poly (thio- or selenophenic) polymer (s) associated or not with one or more counter- anions.

For example, the transparent heating film according to the invention can be formed of PEDOT, optionally in a combined form with one or more counter anions as described above, for example PEDOT: PSS, PEDOT: OTs or PEDOT: OTf .

Also, as mentioned above, the transparent heating film of the invention, preferably formed from poly (thio- or selenophenic) polymer (s) associated or not with one or more counter anions, n is not associated with one or more layers of ancillary electrically conductive materials, for example a layer of metallic nanowires.

Advantageously, the polymeric film according to the invention has a surface resistance less than or equal to 500 ohm / square.

The surface resistance, also called “square resistance”, can be defined by the following formula:

e a.e in which:

e represents the thickness of the conductive film (in cm), σ represents the conductivity of the film (in S / cm) (σ = 1 / ρ), and p represents the resistivity of the film (in Q.cm).

The surface resistance can be measured by techniques known to a person skilled in the art, for example by a 4-point resistivity meter, for example of the Loresta EP type.

Preferably, the transparent heating film according to the invention has a surface resistance less than or equal to 500 ohm / square, in particular less than or equal to 300 ohm / square, preferably less than or equal to 150 ohm / square and more preferably less than or equal to 100 ohm / square.

Eine low electrical resistance improves the heating performance, the thermal power dissipated by the heating film being proportional to V ² / R (Joule effect), V representing the voltage applied across the conductive film (in DC direct current) and R the resistance of the heating film from one terminal to the other.

As illustrated in the examples which follow, a transparent heating film according to the invention thus exhibits good low voltage heating properties. More particularly, it makes it possible to reach a temperature of at least 40 ° C by applying low voltages, for example voltages less than 12 V.

Advantageously, the polymeric film according to the invention also has properties of high transparency.

More particularly, the polymer film has a transmittance, over the entire visible spectrum, of greater than or equal to 70%, in particular greater than or equal to 80% and more particularly greater than or equal to 85%.

The transmittance of a given structure represents the light intensity crossing the structure on the visible spectrum. It can be measured by EiV-Vis-IR spectrometry, for example using an integrating sphere on a Varian Carry 5000 type spectrometer.

The transmittance on the visible spectrum corresponds to the transmittance for wavelengths between 350 and 800 nm.

This transmittance is particularly decisive for guaranteeing a lack of visibility of this film when it is used as a heating element for a heating vision device.

In particular, it is possible with the transparent heating films of the invention to obtain systems which scatter very little light. Typically, Haze factors (diffuse transmission / total transmission) of less than 3%, in particular less than 1% can be obtained, which is a singular advantage for the production of the optoelectronic devices targeted according to the invention.

The polymeric film of the invention thus combines both high electrical conductivity and high transparency properties, allowing it to be used in transparent heating devices, in particular for optical heating, defrosting and / or demisting systems.

The thickness of the conductive and transparent polymer film according to the invention can be between 5 and 1000 nm, preferably between 20 and 200 nm.

The transparent and conductive polymer film according to the invention is advantageously used in a form supported by a base substrate in particular as defined below.

Preparation of conductive and transparent polymer film

The conductive and transparent polymeric film according to the invention can be formed on the surface of a base substrate, according to different variants.

According to a first variant embodiment, the polymer film according to the invention is formed on the surface of the substrate by deposition in the liquid phase, in particular in the aqueous phase, of a material based on poly (thio- or seleno-) phenic polymer, followed by one or more stages of drying and possibly washing.

More particularly, the polymeric film can be formed by application to the surface of the substrate of an aqueous dispersion of poly (thio- or seleno-) phenic polymer, in particular of PEDOT, combined with at least one counteranion, preferably chosen among sodium poly (styrene sulfonate) (PSS), toluene sulfonate or tosylate (OTs), Triflate (OTf) and methylsulfonate (Ms), for example an aqueous dispersion of PEDOT: PSS.

The liquid phase deposition of said material can be carried out by any deposition technique known to a person skilled in the art, for example by soaking, spinning deposition, deposition by nebulization (“spray-coating” in English), deposition by flow coating, inkjet deposition, slot coating deposition ("slot die" in English), impregnation deposition, liquid flow deposition ("flow-coating" in English), dip coating or screen printing.

The layer formed, for example based on PEDOT, can be subjected to one or more stages of drying and optionally washing.

The drying can be carried out by heating at temperatures between 30 ° C and 200 ° C, in particular between 40 and 120 ° C.

Once the deposited layer has dried, it can be soaked in an organic solvent, in particular chosen from N-methyl-2-pyrrolidone (NMP), N, N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), ethylene glycol, Tisopropanol or any other alcohol, then dried again. Such solvents advantageously make it possible to increase the electrical conductivity of the polymer film thus formed.

Alternatively, a small amount of one or more of the above solvents, preferably ethylene glycol or Tisopropanol, can be added to the initial aqueous dispersion of poly (thio- or selenophenic) polymer, then the dried layer .

If necessary, the deposition / drying / washing steps can be repeated several times to reach the desired thickness for the polymer film.

According to a second alternative embodiment, the polymer film can be formed on the surface of said substrate via the in situ polymerization, that is to say directly on the surface of the substrate, of at least one precursor monomer of said poly (thio- or selenophenic).

In the context of this second variant, the polymer film can be more particularly obtained by depositing, on the surface of the substrate, a formulation comprising:

at least one precursor monomer of said poly (thio- or seleno) phenic polymer, for example 3,4-ethylenedioxythiophene (EDOT),

3,4-propylenedioxythiophene (PRODOT) or 3,4-ethylenedioxyselenophene (EDOS); and

one or more species allowing the polymerization of the above-mentioned monomer (s), for example iron triflate (tris complex (iron trifluoromethanesulfonate); and

- one or more solvents, in particular of the alcohol type, preferably chosen from monoacools having from 1 to 5 carbon atoms.

According to a particular embodiment, the formulation of precursor monomers of the poly (thio- or seleno-) phenic polymer further comprises one or more additional solvents chosen in particular from solvents of the amine type, N-methyl-2-pyrrolidone (NMP), Ν, Ν-dimethylformamide (DMF), dimethylsulfoxide (DMSO) or ethylene glycol and isopropanol.

The said additional solvent (s) are used at a rate of at most 20% by mass in the said formulation.

The addition of such solvents advantageously makes it possible to increase the conductivity of the poly (thio- or seleno-) phenic polymer.

The formulation of precursor monomers of the poly (thio- or selenophenic) polymer may also comprise one or more additional polymers of polyethylene glycol type or its derivatives, in particular of the block copolymer polyethylene glycolpolypropylene glycol-polyethylene glycol (PEG-PPG-PEG).

The addition of such a copolymer during the synthesis of the poly (thio- or seleno-) phenic polymer advantageously makes it possible to inhibit the crystallization of the molecules of the solution, to slow down the rate of polymerization and to increase the conductivity of the material. polymer obtained.

The deposition of the formulation on the surface of the substrate can be carried out by any deposition technique in the liquid phase, known to those skilled in the art, such as for example by soaking, spin coating, deposition by nebulization, screen printing, flexography and flowcoating.

The layer formed, for example based on PEDOT, can be subjected to one or more stages of drying and optionally washing.

Drying can be carried out by heating at temperatures between 30 ° C and 200 ° C. Drying can be carried out in an ambient atmosphere or under a controlled atmosphere.

Washing can be carried out with a hydroxylated solvent, typically ethanol, followed by drying of the layer formed.

If necessary, the deposition / drying / washing steps can be repeated several times to reach the desired thickness for the polymer film.

Whatever the variant embodiment of the polymeric film of the invention, it can be formed on a surface of a substrate brought to a temperature of at least 5 ° C.

The polymer film formed can also be annealed at a temperature between 30 and 200 ° C.

TRANSPARENT CONDUCTION HEATING DEVICE

As stated previously, the invention relates, according to another of its aspects, to a transparent conduction heating device comprising at least:

- a substrate having a transmittance, over the entire visible spectrum, of at least 70%;

- a transparent and conductive polymer film, as defined above, as a transparent heating element; and

- contact recovery electrodes.

Substrate

In the context of the present invention, the term “substrate” refers to a solid base structure on at least one of the faces of which the conductive and transparent polymeric film of the invention is formed.

The basic substrate can be of various natures.

It can be a flexible or rigid substrate. It can be flat or not.

It is understood that the substrate is chosen adequately with regard to the intended application for the heating element.

As stated above, the substrate has good transparency properties.

It advantageously has a transmittance, over the entire visible spectrum, of greater than or equal to 70%.

Preferably, the substrate has a transmittance, over the entire visible spectrum, greater than or equal to 80%, in particular greater than or equal to 85%.

The transmittance can for example be measured by UV-Vis-IR spectrometry as indicated previously for the polymer film.

The substrate can thus be a substrate made of glass or of transparent polymers such as polycarbonate, polyolefins, polyethersulfone, polysulfone, phenolic resins, epoxy resins, polyester resins, polyimide resins, polyetherester resins, polyetheramide resins , polyvinyl (acetate), cellulose nitrate, cellulose acetate, polystyrene, polyurethanes, polyacrylonitrile, polytetrafluoroethylene (PTFE), polyacrylates such as polymethyl methacrylate (PMMA), polyarylate, polyetherimides , polyether ketones, polyether ketone ethers, polyvinylidene fluoride, polyesters such as polyethylene terephthalate (PET) or polyethylene naphthalate (PEN), polyamides, zirconia, or their derivatives.

Preferably, the base substrate may be glass, polycarbonate, polyethylene naphthalate (PEN), polyethylene terephthalate (PET), polyimide resin, polymethyl methacrylate (PMMA) or an acrylonitrile / butadiene / styrene copolymer. , commonly called "ABS" (dispersion of butadiene nodules in a matrix of styrene and acrylonitrile copolymer).

The substrate may in particular have a thickness of between 500 nm and 1 cm, in particular between 10 pm and 5 mm.

According to a particular embodiment, the surface of said substrate, intended to support the polymeric film according to the invention, can be subjected to a pre-treatment, in particular of activation, to increase its affinity with the polymeric film.

In particular, this treatment aims to make the surface of said substrate more hydrophilic.

The surface treatment can be carried out dry, for example by UV / ozone or O2 plasma.

It can also be operated wet, for example using an oxidizing solution, for example a mixture of sulfuric acid and hydrogen peroxide, known under the name “Pirahna” solution, such as for example a mixture of H2SO4 / H2O2 3/1.

A person skilled in the art is able to adapt the operating conditions for the implementation of such treatment. For example, the substrate can be activated by immersion in the piranha solution (H2SO4 / H2O2 3/1) for 10 minutes.

Contact recovery electrodes

As is clear from the above, the operation of the heating element according to the invention is based on a Joule effect. It is the transport of a current in the conductive polymer film which generates the heating by Joule effect.

The arrangement of contact recovery electrodes on a heating device of the invention falls within the competence of a person skilled in the art. The contact recovery electrodes are arranged to ensure the circulation of current in the conductive polymer film of the invention.

They can for example be deposited in contact with two opposite edges of the polymer film, as shown in Figures 1 and 3, the heating device of the invention can be used by applying a voltage between the two electrodes.

These contact recovery electrodes can be produced from a metallic deposit. They can for example be produced from a conductive ink or lacquer (preferably based on silver) and / or metallic wires / films.

They can be based on copper, silver, gold, indium, tin, nickel, carbonaceous materials (CNT, graphene for example), and / or conductive polymers.

In particular, the contact recovery electrodes may have a surface resistance less than or equal to 10 ohm / square.

These contact recoveries can be carried out according to usual techniques, for example by chemical vapor deposition CVD (for “Chemical Vapor Deposition” in English) or by physical vapor deposition PVD (for “Physical Vapor Deposition” in English) ).

Contact restorations can also be carried out using metal wires or ribbons, for example copper-based, deposited, fixed or clipped, on the surface intended to support them.

Contact resumption can be carried out before or after the formation of the conductive polymer film according to the invention.

Thus, they can be formed on the surface of the base substrate or on the surface of the conductive polymer film, these two variants being illustrated in FIGS. 1 and 3.

The contact recovery electrodes are connected to a voltage generator.

The electrical supply of the device incorporating a heating element according to the invention can be fixed or nomadic, for example a battery, a battery, and supplied continuously or discontinuously.

Preferably, the voltage generator is capable of generating a supply voltage between 0 and 48 V, in particular between 0 and 20 V, and preferably between 0 and 12 V.

Encapsulation layer

The heating device according to the invention may, in addition, comprise at least one so-called encapsulation layer, present on the external surface of the conductive and transparent polymer film of the invention.

This encapsulation layer can have one or more functions, such as for example being a scratch-resistant, anti-reflection layer, impermeable to water, to oxygen, to thermal conductor and / or to polarization.

It is understood that the nature of the encapsulation layer used depends on the properties expected at the level of this layer with regard to the applications envisaged for the heating device of the invention.

The encapsulation layer is deposited, subsequently to the formation of the polymeric film according to the invention, before or after depositing the contact recovery electrodes.

The encapsulation layer can be formed by liquid or physical deposition.

As an example of a layer deposited in the liquid route, there may be mentioned a layer of varnish.

The encapsulation layer can also be formed by chemical vapor deposition CVD (for “Chemical Vapor Deposition” in English) or also by a process for depositing thin atomic layers ALD (for “Atomic Layer Deposition” in English) from an encapsulation material.

In particular, the encapsulation material may be based on silicon, for example a silicon oxide SiO _x or silicon nitride SiN _x , of aluminum, for example of aluminum nitride (AIN), of oxide of aluminum (AI2O3) or polymers of aluminum oxide known under the name "Alucone", of zirconium, for example of zirconium oxide (ZrCl ·).

It may also be a protective film laminated (or colaminated) on the surface of the polymer film, for example a pressure-sensitive barrier adhesive (PSA).

It is understood that the encapsulation layer must have a high transparency in order to satisfy the transparency requirement of the heating device according to the invention.

Thus, the encapsulation layer advantageously has a transmittance, over the entire visible spectrum, greater than or equal to 70%, in particular greater than or equal to 80% and more particularly greater than or equal to 90%.

The transmittance can for example be measured by UV-Vis-IR spectrometry as indicated previously for the polymer film.

The thickness of the encapsulation layer can vary from 50 nm to 1 mm, in particular from 100 nm to 150 μm.

Preferably, the transparent heating device according to the invention has, as the sole heating element (in other words dedicated to providing a Joule effect), a single conductive and transparent polymer film according to the invention, preferably formed only of polymer (s) poly (thio- or seleno-) phenic (s) in a form combined or not with one or more counter-anion (s).

In particular, the transparent heating film according to the invention is not associated with one or more layers of ancillary electrically conductive materials, for example a layer of metallic nanowires.

For example, the transparent conductive polymeric film according to the invention is not associated with one or more layers of ancillary electrically conductive materials, for example a layer of metallic nanowires.

APPLICATIONS

As mentioned above, the transparent heating device according to the invention advantageously has good heating and transparency performance.

The heating device according to the invention may in particular have an overall transmittance, over the entire visible spectrum, of at least 70%, in particular greater than or equal to 80%.

By "global" transmittance is meant the transmittance of the entire structure of the heating device according to the invention formed by the stack of substrate, polymer film and possibly encapsulation layer according to the invention.

The temperatures for using conduction heating devices in accordance with the invention depend on the conditions of use of the devices or articles with which they are associated and on the thermal stability of their substrates.

Generally they are compatible with a surface temperature of the order of 1 to 250 ° C, and preferably between 2 and 50 ° C.

Furthermore, the heating devices according to the invention diffuse little light.

In particular, they may have a Haze factor of less than 3%, in particular less than 1%.

The Haze factor, expressed as a percentage, can be measured on 25x25 mm thin films using an Agilent Cary 5000 spectrometer equipped with an integrating sphere. This coefficient can be defined by the following formula:

H = T _d / T _avg * 100 in which:

T _avg represents the average value of the total transmittance between 400 and 800 nm;

T _d represents the value of the transmittance scattered between 400 and 800 nm.

The lower this ratio, the less the sample diffuses light and the more an image observed through the transparent device will appear sharp.

Thus, the transparent conduction heating device according to the invention, incorporating as a heating element, the polymeric film according to the invention, can be used for various applications, in particular in heating systems, demisting and / or defrosting.

Man is able to adapt the shape and dimensions of the heating device according to the invention to integrate it into the desired system.

The heating system according to the invention can be used by applying a voltage between the contact recovery electrodes of the heating device according to the invention.

According to another of its aspects, the present invention thus relates to a heating, demisting and / or defrosting system comprising a transparent device for heating by conduction as described above.

In general, the heating, demisting and / or defrosting system can relate to all types of devices known in the state of the art requiring the use of a transparent heating film.

The system can be implemented for example for a glazing, a shower panel, a mirror element, a motorcycle visor, a ski mask, headlight glass, helmets and protective masks, glasses, a heating element of '' an optoelectronic device, for example a display screen, camera lenses, cameras, greenhouses, mirror mirrors.

For example, in the context of the implementation of the heating device according to the invention for a heated windshield, the heating element is intended to heat the windshield in order to demist or defrost it. The performances of the heating device according to the invention in terms of heating and high transparency allow rapid access, within the framework of an application for an automobile windshield, to a clear vision, after activation of the element of heater.

A particularly interesting application of a transparent heating device according to the invention is in particular its implementation for a heating vision device, for example a visor for a helmet or ski mask.

Of course, the invention is not limited to the systems described above, and other applications of the transparent heating device according to the invention can be envisaged.

The invention will now be described by means of the following examples and figures, given by way of non-limiting illustration of the invention.

FIGURES

Figure 1: Schematic representation, in top view (Figure la) and in a vertical sectional plane (Figure lb), the structure of a transparent heating device (1) according to the invention prepared according to Example 1;

Figure 2: Schematic representation of the temperature measurement zones on the heating devices according to Example 1 and 2;

Figure 3: Schematic representation, in top view (Figure 3a) and in a vertical sectional plane (Figure 3b), of the structure of a transparent heating device (2) according to the invention prepared according to Example 2.

It should be noted that, for reasons of clarity, the different elements visible in the figures are shown in free scale, the actual dimensions of the different parts not being observed.

EXAMPLES

Methods of measurement

Total transmittance is measured using an integrating sphere on a Varian Cary 5000 spectrometer.

The transmittance on the visible spectrum corresponds to the transmittance for wavelengths between 350 and 800 nm. The transmittance is measured every 2 nm.

The surface electrical resistance is measured by a 4-point resistivity meter of the Loresta EP type.

EXAMPLE 1

1.1. Creation of a transparent heating device (1)

On a substrate (21) made of polyethylene naphthalate (PEN), are made by sputtering, contact resumptions (11) consisting of a deposit of square shape of 150 nm Au. Before the PEDOT conductive film is deposited, the substrate is activated by O2 plasma treatment (O2, 100 sccm, 120 W, 90 s).

The conductive film is produced by spraying with a PEDOT: PSS solution (PH1000 sold by the company Heraeus) diluted to 25% in Tisopropanol on the substrate heated to 80 ° C. using a Sonotek spray.

After deposition, the film is annealed at 90 ° C for 10 min on a hot plate before being immersed in an ethylene glycol bath for 20 min. A drying step on a hot plate at 120 ° C. makes it possible to obtain a film (31) with a thickness strictly less than 150 nm and a surface resistance strictly less than 100 ohm / square.

A protective layer (41) is formed based on a PSA barrier adhesive laminated to the sample.

The contact recovery electrodes (11) are linked to a low voltage generator (51).

Figure 1 is a schematic representation, in a top view and in a vertical sectional plane, of the heating and transparent device (1) thus obtained.

1.2. Temperature distribution following Joule heating

Figure 2 is used to locate the temperature measurement zones (1, 2, 3, 4, 5 and 6) using a type K thermocouple and to position the contact breakers. The substrate is suspended by the ends to limit heat exchange during heating.

The ambient temperature is 22 ° C.

The surface resistance of the heating film is 100 ohm / square. The transmittance of the heater is 85% at 550 nm.

Table 1 below lists the temperatures measured in the different positions (shown in Figure 2) on the surface of the heating device for different voltages (6 V or 9 V) applied to the contact pickups.

Areas of measured 1 2 3 4 5 6 6 V 40, l ° C 40, l ° C 40.3 ° C 40.0 ° C 40.2 ° C 40.4 ° C 9 V 50.3 ° C 50.5 ° C 50.2 ° C 50.5 ° C 50.3 ° C 50, l ° C

TABLE 1

The surface temperature is homogeneous in the zone of interest with less than 0.5 ° C of variation on the zone swept by the points 1, 2, 3, 4, 5 and 6 represented in figure

2. The temperatures measured are compatible with demisting of the surface.

This embodiment is particularly suitable for a non-planar substrate such as, for example, visors.

EXAMPLE 2

2.1. Creation of a transparent heating device (2)

A polycarbonate substrate (22) is activated by O ₂ plasma treatment (O ₂ , 100 sccm, 120 W, 90 s).

A transparent conductive heating layer (32) of PEDOTOTf is produced by polymerization of EDOT with iron triflate according to the process described in the Supplementary Material part of the article Chem Mater., 2016, pp 3462-8. The residual thickness after drying at 100 ° C for 30 min is 30 nm.

Contact resumption (12) is carried out by depositing with a brush a silver lacquer (Ferro Ag L200). On the silver lacquer strip is deposited a copper wire which is itself connected to a low voltage generator (52).

A resin from Isochem (Varnish 300-1) diluted in n-butanol is then deposited by spraying on this device, and heated at 70 ° C for 2 hours, to form a protective film (42).

Figure 3 is a schematic representation, in a top view and in a vertical sectional plane, of the heating and transparent device (2) thus obtained.

2.2. Temperature distribution following Joule heating

As in Example 1, the temperature is measured in different zones, identified in Figure 2.

The ambient temperature is 22 ° C. The surface resistance of the heating film is 70 ohm / square. The transmittance of the heater is 90% at 550 nm.

Table 2 below lists the temperatures measured in the different positions (shown in Figure 2) on the surface of the heating device for different voltages (6 V or 9 V) applied to the contact pickups.

Areas of measured 1 2 3 4 5 6 6 V 50, l ° C 50, l ° C 50.3 ° C 50.0 ° C 50.2 ° C 50.4 ° C 9 V 60.3 ° C 60.5 ° C 60.2 ° C 60.5 ° C 60.3 ° C 60, l ° C

TABLE 2

The surface temperature is homogeneous in the area of interest with less than 5 0.5 ° C of variation on the area swept by the points 1, 2, 3, 4, 5 and 6 represented in figure

2. The temperatures measured are compatible with demisting of the surface.

Claims (22)

1. Use, as a transparent heating element, in particular in transparent conduction heating devices, of a transparent and conductive polymer film formed to at least 70% by weight of one or more poly (thio) polymer (s) - or seleno-) phenic (s) in a form combined or not with one or more counter-anion (s), said film not comprising a percolating network of electrically conductive ancillary materials. 2. Use according to claim 1, wherein said conductive and transparent polymeric film is free of electrically conductive ancillary materials. 3. Use according to claim 1 or 2, wherein the conductive and transparent polymeric film is formed only of one or more poly (thioou selenophenic) polymer (s) in a form combined or not with one or more contreanion (s). 4. Use according to any one of the preceding claims, in which said poly (thio- or selenophenic) polymer is a polythiophenic polymer derived from the polymerization of monomer (s) chosen from thiophene, 3alkylthiophenes, 3 , 4-dialkylthiophenes, 3,4-cycloalkylthiophenes, 3,4-dialkoxythiophenes, and 3,4-alkylenedioxythiophenes, in which the identical or different alkyl groups have the formula C _n H _2n + i with n between 1 and 12 . 5. Use according to the preceding claim, in which the polythiophenic polymer derives from the polymerization of monomer (s) chosen (s) thiophene, 3.4- ethylenedioxythiophene (EDOT), 3-hexylthiophene and 3,4propy 1 enenedioxythiophene (PRODOT). 6. Use according to any one of claims 1 to 3, in which the poly (thio- or seleno-) phenic polymer is a polyselenophenic polymer derived from the polymerization of selected monomer (s) selenophene, the 3, 4-dialkylselenophenes, 3.4- cycloalkylselenophenes, 3,4-dialkoxyselenophenes, and 3,4-alkylenedioxyselenophenes, in which the alkyl groups, identical or different, have the formula C _n H _2n + i with n between 1 and 12. 7. Use according to the preceding claim, in which the polyselenophenic polymer is derived from the polymerization of monomer (s) chosen from selenophene, 3,4-ethylenedioxy selenophene (EDOS), 3-hexylselenophene, and 3 , 4propy 1 enedi oxy sel enophene (PRODO S). 8. Use according to any one of the preceding claims, in which the counter anion is of the triflate, sulfonate, triflimidate, mesylate, perchlorate and hexafluorophosphate type, in particular is chosen from sodium poly (styrene sulfonate) (PSS), tosylate (OTs), triflate (OTf) and methylsulfonate (Ms). 9. Use according to any one of the preceding claims, in which said conductive and transparent polymeric film is based on poly (3,4ethylenedioxythiophene) (PEDOT), in particular combined with a counter anion chosen from poly (styrene sulfonate) of sodium (PSS), tosylate (OTs), triflate (OTf) and methylsulfonate (Ms), and more particularly based on PEDOT: PSS, PEDOT: OTs or PEDOT: OTf. 10. Use according to any one of the preceding claims, in which said conductive and transparent polymeric film has a transmittance, over the entire visible spectrum, greater than or equal to 70%, in particular greater than or equal to 80% and more particularly greater than or equal to 85%. 11. Use according to any one of the preceding claims, in which said conductive and transparent polymeric film has a surface resistance less than or equal to 500 ohm / square, in particular less than or equal to 300 ohm / square, preferably less than or equal to 150 ohm / square and more preferably less than or equal to 100 ohm / square. 12. Use according to any one of the preceding claims, in which said conductive and transparent polymeric film is supported by a substrate having a transmittance, over the entire visible spectrum, greater than or equal to 70%. 13. Transparent conduction heating device, comprising at least: - a substrate having a transmittance, over the entire visible spectrum, of at least 70%; - as a transparent heating element, a conductive and transparent polymer film formed to at least 70% by weight of one or more poly (thio- or selenophenic) polymer (s) in a combined or non-combined form with one or more counter-anion (s) and not comprising a percolating network of ancillary electrically conductive materials, preferably being free of ancillary electrically conductive materials, said film being supported by the substrate; - contact recovery electrodes. 14. Device according to the preceding claim further comprising, on the external surface of said conductive and transparent polymer film, at least one encapsulation layer having a transmittance, over the entire visible spectrum, greater than or equal to 70%, in particular greater or equal to 80% and more particularly greater than or equal to 90%. 15. Device according to claim 13 or 14, wherein the polymeric film is as defined according to any one of claims 2 to 11. 16. Device according to any one of claims 13 to 15, in which the substrate is made of glass or of transparent polymers such as polycarbonate, polyolefins, polyethersulfone, polysulfone, phenolic resins, epoxy resins, polyester resins , polyimide resins, polyetherester resins, polyetheramide resins, polyvinyl (acetate), cellulose nitrate, cellulose acetate, polystyrene, polyurethanes, polyacrylonitrile, polytetrafluoroethylene (PTFE), polyacrylates such as polymethyl methacrylate (PMMA), polyarylate, polyetherimides, polyether ketones, polyether ether ketones, polyvinylidene fluoride, polyesters such as polyethylene terephthalate (PET) or polyethylene naphthalate (PEN), polyamides, zirconia, or their derivatives. 17. A method of preparing a transparent conduction heating device, comprising at least the steps consisting in (i) having a substrate having a transmittance, over the entire visible spectrum, of at least 70%; (ii) forming, on all or part of the surface of at least one of the faces of said substrate, a conductive and transparent polymeric film formed at least 70% by weight of one or more poly (thio) polymer (s) - or seleno-) phenic (s) in a form combined or not with one or more counter anion (s), and not comprising a percolating network of annexed electrically conductive materials, preferably being free of annexed electrically conductive materials; and (iii) establish contact recovery electrodes, step (iii) being carried out before or after the formation of said conductive and transparent polymeric film. 18. Method according to the preceding claim, in which the conductive and transparent polymer film in step (ii) is formed on the surface of the substrate by deposition in liquid phase, in particular in aqueous phase, of a material based on poly (thio polymer). - or seleno-) phenic, followed by one or more stages of drying and possibly washing. 19. The method of claim 17, wherein the conductive and transparent polymer film in step (ii) is formed on the surface of said substrate by in situ polymerization of at least one precursor monomer of said poly (thio- or selenophenic) polymer. 20. Method according to any one of claims 17 to 19, in which the surface of said substrate, intended to support the polymeric film, is subjected to a pretreatment, prior to the formation of the polymeric film of step (ii), in in particular an activation treatment, said treatment being more particularly carried out by the dry route, in particular by UV / ozone or plasma O2 or by the wet route, in particular using an oxidizing solution, in particular a mixture of sulfuric acid and hydrogen peroxide. 21. A heating, demisting and / or defrosting system comprising a transparent conduction heating device as defined according to any one of claims 13 to 16. 22. System according to the preceding claim, said system being implemented for a glazing, a shower panel, a mirror element, a motorcycle visor, a ski mask, headlight glass, helmets and protective masks, glasses , a heating element of an optoelectronic device, for example a display screen, camera lenses, cameras, heated greenhouses, rear-view mirrors, in particular for a helmet visor or a ski mask. 1/2