TECHNICAL FIELD

The present disclosure relates to an electrically conductive multilayer film. The present disclosure further relates to a method for producing an electrically conductive multilayer film. The present disclosure further relates to the use of a transparent primer layer, to a touch sensing device, and to the uses of the electrically conductive multilayer film and of the touch sensing device.

BACKGROUND

Electrically conductive multilayer films are used in many different applications including touch sensing devices, photovoltaic systems, heating appli cations, and lighting systems. Such conductive films may be manufactured by e.g. using multiple layers of different materials, to achieve e.g. improved strength, stability, appearance or other properties from the use of differing materials. When forming a conductive film of different layers of material, their adhesion and bonding ability is of importance in order to avoid detachment of the distinct layers during the use thereof.

SUMMARY

An electrically conductive multilayer film is disclosed. The electrically conductive multilayer film may comprise a non-conductive base layer, a transparent layer comprising transparent conductor material, and a transparent primer layer. The non- conductive base layer, the transparent layer comprising transparent conductor material, and the transparent primer layer can be arranged one on the other in a vertical direction such that the transparent primer layer is situated between the non- conductive base layer and the transparent layer comprising transparent conductor material and is in direct contact with the transparent layer comprising transparent conductor material. The transparent primer layer may be formed of a composition comprising a polymer, wherein the polymer is selected from a group consisting of polyvinylidene chloride, a copolymer, wherein one of the monomers is vinylidene chloride, and any combination thereof.

An electrically conductive multilayer film is disclosed. The electrically conductive multilayer film may comprise a non-conductive base layer, a transparent layer comprising transparent conductor material, and a transparent primer layer. The non- conductive base layer, the transparent layer comprising transparent conductor material, and the transparent primer layer can be arranged one on the other in a vertical direction such that the transparent primer layer is situated between the non- conductive base layer and the transparent layer comprising transparent conductor material and is in direct contact with the transparent layer comprising transparent conductor material. The transparent primer layer may be formed of a composition comprising a polymer, wherein the polymer is selected from a group consisting of polyvinylidene chloride, a copolymer, wherein one of the monomers is vinylidene chloride, and any combination thereof, wherein and wherein the thickness of the transparent primer layer is 150 2000 nm.

Further, a method for producing an electrically conductive multilayer film is disclosed. The method may comprise: providing a non-conductive base layer; providing, on the non-conductive base layer, a transparent primer layer, wherein the transparent primer layer is formed of a composition comprising a polymer, wherein the polymer is selected from a group consisting of polyvinylidene chloride, a copolymer, wherein one of the monomers is vinylidene chloride, and any combination thereof; and providing, on the transparent primer layer and in direct contact with the transparent primer layer, a transparent layer comprising transparent conductor material.

Further, a method for producing an electrically conductive multilayer film is disclosed. The method may comprise: providing a non-conductive base layer; providing, on the non-conductive base layer, a transparent primer layer, wherein the transparent primer layer is formed of a composition comprising a polymer, wherein the polymer is selected from a group consisting of polyvinylidene chloride, a copolymer, wherein one of the monomers is vinylidene chloride, and any combination thereof, and wherein the thickness of the transparent primer layer is 150 2000 nm; and providing, on the transparent primer layer and in direct contact with the transparent primer layer, a transparent layer comprising transparent conductor material.

Further, a touch sensing device is disclosed. The touch sensing device may comprise an electrically conductive multilayer film as disclosed in the present disclosure .

Further, uses of the transparent primer layer, of the electrically conductive multilayer film, and of the touch sensing device are disclosed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a further understanding of the embodiments and constitute a part of this specification, illustrate various embodiments. In the drawings: Fig. 1 illustrates schematically a sectional view of an electrically conductive multilayer film ac cording to one embodiment; and

Fig. 2 illustrates schematically a sectional view of an electrically conductive multilayer film according to one embodiment.

DETAILED DESCRIPTION

The present application relates to an electrically conductive multilayer film comprising a non-conductive base layer, a transparent layer comprising transparent conductor material, and a transparent primer layer, wherein the non-conductive base layer, the transparent layer comprising transparent conductor material, and the transparent primer layer are arranged one on the other in a vertical direction such that the transparent primer layer is situated between the non-conductive base layer and the transparent layer comprising transparent conductor material and is in direct contact with the transparent layer comprising transparent conductor material, and wherein the transparent primer layer is formed of composition comprising a polymer, wherein the polymer is selected from a group consisting of polyvinylidene chloride, a copolymer, wherein one of the monomers is vinylidene chloride, and any combination thereof.

The present application relates to an electrically conductive multilayer film comprising a non-conductive base layer, a transparent layer comprising transparent conductor material, and a transparent primer layer, wherein the non-conductive base layer, the transparent layer comprising transparent conductor material, and the transparent primer layer are arranged one on the other in a vertical direction such that the transparent primer layer is situated between the non-conductive base layer and the transparent layer comprising transparent conductor material and is in direct contact with the transparent layer comprising transparent conductor material, and wherein the transparent primer layer is formed of composition comprising a polymer, wherein the polymer is selected from a group consisting of polyvinylidene chloride, a copolymer, wherein one of the monomers is vinylidene chloride, and any combination thereof, and wherein the thickness of the transparent primer layer is 150 - 2000 nm.

The expression "any combination thereof" should be understood in this specification, unless otherwise stated, as meaning any combination of the polyvinylidene chloride and the copolymer.

The present application further relates to a method for producing an electrically conductive multi layer film, wherein the method comprises:

- providing a non-conductive base layer;

- providing, on the non-conductive base lay er, a transparent primer layer, wherein the transpar ent primer layer if formed of a composition comprising a polymer, wherein the polymer is selected from a group consisting of polyvinylidene chloride, a copoly mer, wherein one of the monomers is vinylidene chlo ride, and any combination thereof; and

- providing, on the transparent primer layer and in direct contact with the transparent primer lay er, a transparent layer comprising transparent conduc tor material.

The present application further relates to a method for producing an electrically conductive multi layer film, wherein the method comprises:

- providing a non-conductive base layer;

- providing, on the non-conductive base lay er, a transparent primer layer, wherein the transpar ent primer layer if formed of a composition comprising a polymer, wherein the polymer is selected from a group consisting of polyvinylidene chloride, a copoly mer, wherein one of the monomers is vinylidene chlo ride, and any combination thereof, and wherein the thickness of the transparent primer layer is 150 2000 nm; and

- providing, on the transparent primer layer and in direct contact with the transparent primer lay er, a transparent layer comprising transparent conduc tor material.

The present application further relates to the use of a transparent primer layer in an electrically conductive multilayer film according to the present application for improving the adhesion of the transparent layer comprising transparent conductor material to the non-conductive base layer, for improving the electrical performance of the electrically conductive multilayer film, for strengthening the mechanical and/or environmental stability of the electrically conductive multilayer film, and/or for improving the optical reliability of the electrically conductive multilayer film.

The present application further relates to the use of a transparent primer layer formed of a composition comprising a polymer, wherein the polymer is selected from a group consisting of polyvinylidene chloride, a copolymer, wherein one of the monomers is vinylidene chloride, and any combination thereof, and wherein the thickness of the transparent primer layer is 150 - 2000 nm, in an electrically conductive multilayer film according to the present application for improving the adhesion of the transparent layer comprising transparent conductor material to the non- conductive base layer, for improving the electrical performance of the electrically conductive multilayer film, for strengthening the mechanical and/or environmental stability of the electrically conductive multilayer film, and/or for improving the optical reliability of the electrically conductive multilayer film.

The present application further relates to a touch sensing device comprising an electrically conductive multilayer film of the present application.

The present application further relates to the use of an electrically conductive multilayer film according to the present application in a touch sensor, in a photovoltaic system, in a heating application, in a current conductor, in a display system, in a display electrode, in a lighting system, in a light switch, or in a light control film.

The present application further relates to the use of a touch sensing device according to the present application in a photovoltaic system, in a heating application, in a current conductor, in a display system, in a display electrode, in a lighting system, in a light switch, or in a light control film.

The expression that the transparent layer comprising transparent conductor material is provided "on" the transparent primer layer should be understood in this specification, unless otherwise stated, as meaning that the transparent layer comprising trans parent conductor material is provided or formed to lie on or upon the transparent primer layer or is being at least partly embedded therein. The transparent primer film may serve as a carrier or support structure for the transparent layer comprising transparent conductor material .

The term "comprising" is used in this speci fication to mean including the feature (s) or act(s) followed thereafter, without excluding the presence of one or more additional features or acts.

It will further be understood that reference to "an" item refers to one or more of those items. The expression "film" should be understood in this specification, unless otherwise stated, as referring to a structure having its lateral dimensions substantially larger than its thickness. In that sense, a film may be considered as being a "thin" structure .

In one embodiment, the thickness of the elec trically conductive multilayer film is 0.5 nm - 6 mm. In one embodiment, the thickness of the electrically conductive multilayer film is 0.5 nm - 1000 nm. In one embodiment, the thickness of the electrically conduc tive multilayer film is 0.1 ym - 6 mm.

The expression that the base layer is "non- conductive" should be understood in this specifica tion, unless otherwise stated, as meaning that the base layer has a sheet resistance of 10 Mohms/square or higher.

The expression "transparent" should be under stood in this specification, unless otherwise stated, as referring to optical transparency of the film, lay er, or the parts and materials thereof in the relevant wavelength range at issue. In other words, "transpar ent" material or structure refers to a material or structure allowing light, or generally electromagnetic radiation, at such relevant wavelength to propagate through such material or structure. The relevant wave length range may depend on the application where the electrically conductive multilayer film is to be used. In one embodiment, the relevant wavelength range is the visible wavelength range of about 390 to about 700 nm. In one embodiment, the relevant wavelength range is the infrared radiation wavelength range of about 700 to about 1000 nm.

Further, the transparency of the film, layer or the parts thereof primarily refers to the transpar ency in the thickness direction of the film, layer, or the parts thereof so that in order to be "transpar- ent", sufficient portion of light energy incident on the film, layer, or a part thereof shall propagate through it in the thickness direction. Such sufficient portion may depend on the application in which the film is to be used. In one embodiment, the transmit tance of the film, layer, or the parts thereof is 20 - 99.99 % of the energy of light incident perpendicular ly thereon. In one embodiment, said transmittance is 20 % or higher, or 30 % or higher, or 40 % or higher, or 50 % or higher, or 60 % or higher, or 70 % or high er, or 80 % or higher, 90 % or higher. The transmit tance may be measured according to standard JIS-K7361, ASTM D1003.

In one embodiment, the transparent primer layer comprises or consists of a polymer, wherein the polymer is selected from a group consisting of polyvinylidene chloride, a copolymer, wherein one of the monomers is vinylidene chloride, and any combination thereof. In one embodiment the transparent primer layer is formed of a composition comprising or consisting of a polymer, wherein the polymer is selected from a group consisting of polyvinylidene chloride; a copolymer wherein one of the monomers is vinylidene chloride; and any combination thereof. In one embodiment, the main component of the copolymer is vinylidene chloride. In one embodiment, the copolymer is a copolymer of vinylidene chloride and vinyl chloride (VDC-VC copolymer) . In one embodiment, the copolymer comprises, in addition to vinylidene chloride, at least one monomer selected from a group consisting of vinyl chloride, vinyl acrylate, vinyl methacrylate, and acrylonitrile. In one embodiment, the transparent primer layer comprises 0.02 - 0.2 mg, or 0.02 - 0.1 mg, of polymer per cm ² . In one embodiment, the transparent primer layer comprises 90 - 100 weight-%, or 95 - 99 weight-%, or 96 98 weight-% of the polymer based on the total weight of the transparent primer layer.

In one embodiment, the transparent primer layer is formed by using a composition comprising 0.1 - 100 %, or 0.1 - 30 %, or 0.1 - 15 %, or 0.5 - 8 %, or 2 - 6 %, or 3 - 5 %, or about 4 %, of the polymer by weight based on the total volume of the composition. In one embodiment, the composition comprises, in addition to the polymer, a solvent. In one embodiment, the composition consists of a polymer and a solvent. In one embodiment, the composition consists of a polymer and a solvent, and optionally at least one additive. In one embodiment, the composition comprises at least one additive. In one embodiment, the at least one additive is selected from a group consisting of a plasticizer, a wax, a resin, a filler, a pigment, a dye, an anti-corrosive, a stabilizer, and an UV absorber.

The inventors surprisingly found out that using a composition comprising a polymer that is polyvinylidene chloride, a copolymer of vinylidene chloride, or a combination thereof, as the material of the transparent primer layer improves the adhesion of the transparent layer comprising transparent conductor material to the non-conductive base layer and thus enables a prolonged life time of the formed electrically conductive multilayer film while reducing detachment of the transparent layer comprising transparent conductor material from the other layers. Further, the inventors surprisingly noted that the use of a composition comprising a polymer that is polyvinylidene chloride, a copolymer of vinylidene chloride, or a combination thereof, as the material of the transparent primer layer has the added utility of improving the stability of the electrical conductivity of the electrically conductive multilayer film. The use of the primer layer has the added utility of improving the electrical conductivity of the electrically conductive multilayer film by making the sheet resistance thereof more stable.

In one embodiment, the thickness of the transparent primer layer is at least 50 nm and at most 10 ym. In one embodiment, the thickness of the transparent primer layer is at least 50 nm, or 50 - 2000, or 50 - 1000 nm, or 150 - 500 nm. If the thickness of the transparent primer layer is thinner than 50 nm, then the sheet resistance may increase faster compared to the situation when the thickness is at least 50 nm. Keeping the thickness of the transparent primer layer at a value of at most 1000 nm has the added utility that the optical property is not degraded as may be the situation if the thickness is above 1000 nm. However, in some embodiments the thickness of the transparent primer layer may be thicker, e.g. in the situation that the non-conductive base layer is a non-conductive non-transparent base layer .

In one embodiment, the transparent conductor material is at least partly embedded into the transparent primer layer. In one embodiment, the transparent conductor material is embedded into the transparent primer layer.

In one embodiment, the transparent primer layer is in direct contact with the non-conductive base layer and with the transparent layer comprising transparent conductor material.

In one embodiment, the non-conductive base layer is a non-conductive non-transparent base layer. In one embodiment, the non-conductive base layer is a non-conductive transparent base layer. In one embodi ment, the non-conductive base layer is translucent and/or opaque.

In one embodiment, the non-conductive base layer is made of dielectric material. In one embodi- ment, the material used to form the non-conductive base layer should be suitable for serving as a sub strate for the transparent primer layer as well as for the transparent layer comprising transparent conductor material. In one embodiment, the non-conductive base layer comprises or consists of polymer or glass. In one embodiment, the non-conductive base layer is formed of transparent plastic material. In one embodi ment, the material of the non-conductive base layer is selected from a group consisting of polyethylene ter- ephthalate (PET) , polycarbonate (PC) , polymethyl meth acrylate (PMMA) , cyclic olefin polymer (COP) , tri acetate (TAC) , cyclic olefin copolymer (COC) , poly (vinyl chloride) (PVC) , poly (ethylene 2,6- naphthalate (PEN), polyimide (PI), polypropylene (PP) , polyethylene (PE), and any combination thereof. In one embodiment, the material of the non-conductive base layer is selected from a group consisting of float glass (comprising of Si0 ₂ , Na ₂ 0, CaO, MgO) , sodalime, aluminosilicate glass, and borosilicate glass. The ma terial of the non-conductive base layer is not, howev er, limited to these examples.

In one embodiment, the non-conductive base layer has a thickness of 1 - 5000 pm, or 10 - 2000 pm, or 30 to 500 pm, or 50 - 300 pm. However, the non- conductive base layer may also be thicker in some ap plications .

In one embodiment, no further adhesive is used to bond together the non-conductive base layer, the transparent primer layer, and/or the transparent layer comprising transparent conductor material.

The transparent conductor material may com prise any appropriate, sufficiently transparent con ductor material or any combination of such materials.

In one embodiment, the transparent conductor material comprises or consists of a conductive high aspect ratio molecular structure (HARMS) network. In one embodiment, the transparent conductor material comprises a conductive high aspect ratio molecular structure (HARMS) network.

A conductive "HARMS" or a "HARM structure" refers to electrically conductive "nanostructures", i.e. structures with one or more characteristic dimen sions in nanometer scale, i.e. less or equal than about 100 nanometers. "High aspect ratio" refers to dimensions of the conductive structures in two perpen dicular directions being in significantly different magnitudes of order. For example, a nanostructure may have a length which is tens or hundreds times higher than its thickness and/or width. In a HARMS network, a great number of said nanostructures are interconnected with each other to form a network of electrically in terconnected molecules. As considered at a macroscopic scale, a HARMS network forms a solid, monolithic mate rial in which the individual molecular structures are disoriented or non-oriented, i.e. are oriented sub stantially randomly, or oriented. Various types of HARMS networks can be produced in the form of thin transparent layers with reasonable resistivity.

In one embodiment, the conductive HARM struc tures comprise metal nanowires, such as silver nan owires .

In one embodiment, the conductive HARM net work comprises carbon nanostructures. In one embodi ment, the carbon nanostructures comprise carbon nano tubes, carbon nanobuds, carbon nanoribbons, or any combination thereof. In one embodiment, the carbon nanostructures comprise carbon nanobuds, i.e. carbon nanobud molecules. The carbon nanobuds or the carbon nanobud molecules, have fullerene or fullerene-like molecules covalently bonded to the side of a tubular carbon molecule. Carbon nanostructures, especially carbon nanobuds, may provide advantages both from electrical, optical (transparency) , and mechanical (robustness combined with flexibility and/or deforma- bility) points of view.

In one embodiment, the transparent conductor material comprises or consists of a transparent con ductive oxide. In one embodiment, the transparent con ductor material comprises or consists of indium tin oxide (ITO), zinc oxide, aluminium-doped zinc oxide (AZO) , fluorine doped tin oxide (FTO) , or any combina tion thereof. In one embodiment, the transparent con ductor material comprises a transparent conductive ox ide. In one embodiment, the transparent conductive ox ide is indium tin oxide (ITO), zinc oxide, aluminium- doped zinc oxide (AZO) , fluorine doped tin oxide (FTO), or any combination thereof. In one embodiment, the transparent conductive oxide is doped with a dop ing agent, such as fluorine.

In one embodiment, the transparent conductor material comprises or consists of graphene, silver nanowires, poly (3, 4-ethylenedioxythiophene) PEDOT, poly (3, 4-ethylenedioxythiophene) polystyrene sulfonate PEDOT:PSS, polyaniline, a metal mesh conductor, or any combination thereof. In one embodiment, the transpar ent conductor material comprises graphene, silver nan owires, poly (3, 4-ethylenedioxythiophene) PEDOT, poly (3, 4-ethylenedioxythiophene) polystyrene sulfonate PEDOT:PSS, polyaniline, a metal mesh conductor, or any combination thereof.

In one embodiment, the transparent conductor material is doped.

The thickness of a transparent layer compris ing transparent conductor material may be designed in accordance with the properties of the transparent con ductor material, especially the resistivity or conduc tivity thereof. For example, in the case of the trans parent conductor material comprising carbon nanostruc tures, the transparent layer may have, for example, a thickness of 1 - 1000 nm. In one embodiment, the thickness of the transparent layer comprising trans parent conductor material is 0.1 - 1000 nm, or 10 - 100 nm, or 100 - 500 nm.

In one embodiment, the non-conductive base layer comprises or consists of polycarbonate, the transparent conductor material comprises or consists of a conductive HARMS network, and the transparent primer layer is formed of the composition comprising or consisting of a polymer, wherein the polymer is se lected from a group consisting of polyvinylidene chlo ride, a copolymer, wherein one of the monomers is vi- nylidene chloride, and any combination thereof. The inventors surprisingly found out that this combination has the added utility of the above polymer primer lay er providing good adhesion for the conductive HARMS network while simultaneously acting as a moisture and gas barrier thus shielding the HARMS network from neg ative environmental influences.

In one embodiment, the method comprises providing a non-conductive base layer. In one embodi ment, providing a non-conductive base layer comprises making available, a complete non-conductive base layer formed and manufactured beforehand. Such non- conductive base layer may be first prepared, by any appropriate process. In one embodiment, the non- conductive base layer is provided by an extrusion pro cess and/or a casting process. In one embodiment, providing a non-conductive base layer comprises manu facturing the non-conductive base layer as a part of the method for producing the electrically conductive multilayer film. In one embodiment, the non-conductive base layer formed of at least two layers of different materials or of the same material. I.e. the non- conductive base layer can be formed of e.g. extruded or coated layers arranged one on the other.

In one embodiment, the transparent primer layer is provided on the non-conductive base layer by using a coating process. In one embodiment, the trans parent primer layer is provided by using slot-die coating, roller coating, rod coating, curtain coating, inkjet printing, a dip coating, or screen printing.

In one embodiment, providing, on the trans parent primer layer, the transparent layer comprising transparent conductor material comprises forming or depositing transparent conductor material on the transparent primer layer.

Depending on the material of the transparent layer comprising transparent conductor material, vari ous procedures existing in the art may be used for providing the transparent layer comprising transparent conductor material. For example, ITO may be deposited by sputtering in vacuum conditions. PEDOT or silver nanowires may be formed, for example, by printing. Metal meshes may be formed, for example, by printing or electroplating or by any other appropriate method.

In the case of the transparent conductor ma terial comprising carbon nanostructures, such as car bon nanobud molecules, deposition may be carried out, for example, by using the commonly known methods of filtration from gas phase or from liquid, deposition in a force field, or deposition from a solution using spray coating or spin drying. The carbon nanobud mole cules can be synthesized, for example, using the meth od disclosed in WO 2007/057501, and deposited on a substrate, for example, directly from the aerosol flow, e.g. by assistance of e.g. electrophoresis or thermophoresis, or by a method described in Nasibulin et al : "Multifunctional Free-Standing Single-Walled 20 Carbon Nanotube Films", ACS NANO, vol. 5, no. 4, 3214- 3221, 2011.

In one embodiment, the transparent conductor material is formed or deposited in a predetermined pattern on the transparent primer layer. In one embod iment, a predetermined pattern is formed in the trans- parent layer after having formed or deposited the transparent conductor material on the transparent pri mer layer. In said patterning, various processes may be used. In one embodiment, a laser process, an etch ing process, direct printing, a mechanical process, a burning process, or any combination thereof, is used for the patterning. In one embodiment, the laser pro cess is laser ablation. In one embodiment, the etching process is a photolithographic process. In one embodi ment, the pattern is formed simultaneously or after the transparent layer comprising transparent conductor material is formed or deposited on the transparent primer layer.

In one embodiment, the transparent layer com prising transparent conductor material is at least partly covered with transparent dielectric material forming a coating layer on the transparent layer com prising transparent conductor material. In one embodi ment, the transparent layer comprising transparent conductor material is situated between the coating layer and the transparent primer layer. In one embodi ment, the thickness of the coating layer is 10 - 600 nm, or 20 - 500 nm, or 30 - 400 nm, or 50 - 300 nm, or 60 - 200 nm, or 70 - 150 nm. In on embodiment, the thickness of the coating layer is 50 - 150 nm. The thickness of the coating layer can be configured such that further processing of the transparent layer com prising transparent conductor material through the coating layer is enabled. In one embodiment, the pro cessing of the transparent layer comprising transpar ent conductor material through the coating layer com prises laser etching (patterning) , printing of elec tric contacts (screen printing) , or any other type of processing, of the transparent layer comprising trans parent conductor material. In one embodiment, the printing of electric contacts comprises printing Ag contacts . In one embodiment, the transparent conductor material is partly embedded in the transparent dielectric material such that at least a part of the transparent conductor material is exposed. In one embodiment, the transparent conductor material is partly embedded in the transparent dielectric material such that at least a part of the transparent conductor material extends out of the coating layer.

In one embodiment, the transparent dielectric material comprises or consists of a polymer. In one embodiment, the transparent dielectric material comprises or consists of a polymer, wherein the polymer is selected from a group consisting of polyvinylidene chloride (PVDC) , a copolymer, wherein one of the monomers is vinylidene, poly (methyl methacrylate) (PMMA) , polycarbonate (PC) , and a combination thereof. In one embodiment, the polymer is selected from a group consisting of polyvinylidene chloride (PVDC), poly (methyl methacrylate) (PMMA), polycarbonate (PC) , low-density polyethylene (LDPE) , polypropylene (PP) , polyurethane (PU) , polyethylene terephthalate (PET) , ethylene vinyl alcohol (EVOH) , and a combination thereof. In one embodiment, the polymer is selected from a group consisting of polyvinylidene chloride, a copolymer, wherein one of the monomers is vinylidene chloride, and any combination thereof. In one embodiment, the polymer is polycarbonate .

In one embodiment, the transparent dielectric material further comprises a solvent, an optical ab sorbing additive, a dopant, an adhesion promoter, a hardener, or any combination thereof. The optical ab sorbing additive may provide the protection against environmental UV radiation.

In one embodiment, the coating layer compris es 0.005 - 0.06 mg, or 0.005 - 0.03 mg, of polymer per cm ² . In one embodiment, the coating layer comprises 90 - 100 weight-%, or 95 - 99 weight-%, or 96 - 98 weight-% of the transparent dielectric material, e.g. the polymer, based on the total weight of the coating layer. In one embodiment, coating layer of transparent dielectric material is formed by using a composition comprising 0.1 - 100 %, or 0.1 - 30 %, or 0.1 - 15 %, or 0.1 - 6 %, or 0.3 - 5 %, or 0.5 - 4 %, of the poly mer by weight based on the total volume of the compo sition.

In one embodiment, the method comprises covering the transparent layer comprising transparent conductor material at least partly with transparent dielectric material to form a coating layer of transparent dielectric material having a thickness of 10 - 600 nm. In one embodiment, covering the transparent layer comprising transparent conductor material at least partly with transparent dielectric material is carried out by using at least one of the following processes: slot die coating, meniscus coating, roller coating, screen printing, gravure coating, flexo coating, offset coating, knife coating, physical vapor deposition.

In one embodiment, at least one metallic con tact pad is provided. In one embodiment, at least one metallic contact pad is provided on the transparent layer comprising transparent conductor material. In one embodiment, the at least one metallic contact pad is provided by using screen printing or ink-jet print ing. In one embodiment, the at least one metallic con- tact pad comprises silver, gold, copper or any combi nation thereof.

In one embodiment, the electrically conduc tive multilayer film comprises at least one additional component attached thereto. In one embodiment, the ad- ditional component is essentially transparent. In one embodiment, the additional component is essentially non-transparent. In one embodiment, the additional component is selected from a group consisting of a silicon chip, a piezo vibrator, a force sensor, a light emitting diode (LED), and a light guide. In one embodiment, the electrically conductive multilayer film is provided with at least one additional compo nent attached thereto, wherein the additional compo nent is selected from a group consisting of a silicon chip, a piezo vibrator, a force sensor, a light emit ting diode (LED), and a light guide.

In one embodiment, the method comprises providing at least one additional layer on the elec trically conductive multilayer film. In one embodi ment, the electrically conductive multilayer film com prises or is provided with at least one additional layer. In one embodiment, at least one of the at least one additional layers is essentially transparent. In one embodiment, at least one of the at least one addi tional layers is essentially non-transparent. In one embodiment, at least one of the at least one addition al layers is a decorative layer. The decorative layer may for example be used to form a pattern on the elec trically conductive multilayer film e.g. to provide location information for touch. In one embodiment, a protecting layer is provided on the electrically con ductive multilayer film. The additional layer may com prise base or cover plates. Any of the base and cover plates may comprise a transparent plastic material, such as acrylate or PC or a multilayer laminate of these, or a glass material, such as a float glass (comprising of Si0 ₂ , Na ₂ 0, CaO, MgO) , sodalime, or alu minosilicate or borosilicate glass, or a laminate con sisting of such glass and/or plastic materials. A typ ical automotive safety glass may comprise two float glass sheets with a plastic e.g. polyvinyl butyral (PVB) embedded in-between.

In one embodiment, the electrically conduc tive multilayer film is subjected to thermoforming and/or injection molding. In one embodiment, the elec trically conductive multilayer film is formed to have a three-dimensional shape.

In one embodiment, the electrically conduc tive multilayer film is formable, flexible, foldable, and/or stretchable. In one embodiment, the electrical ly conductive multilayer film is formable and/or stretchable. In one embodiment, the electrically con ductive multilayer film is formable and stretchable. In one embodiment, the electrically conductive multi layer film is formable.

In one embodiment, the electrically conduc tive multilayer film is formed as a flexible structure so as to allow bending thereof, preferably reversibly and repeatedly, along a three dimensional surface in at least one direction. In one embodiment, the elec trically conductive multilayer film is bendable in at least one direction. In one embodiment, the electri cally conductive multilayer film is bendable in at least two directions simultaneously. Depending on the material used for producing the electrically conduc tive multilayer film, the smallest radius of curvature in which the electrically conductive multilayer film may be bent may lie, for example, in the range of 0.5 mm to 3 or 10 mm. In one embodiment, the radius of curvature in which the electrically conductive multi layer film may be bent lies in the range of 0.5 mm to 3 or 10 mm. The smallest radius of curvature may be achieved for transparent layers comprising carbon nanostructures such as carbon nanobuds, whereas for other materials, the lowest possible radius of curva ture may be higher.

In one embodiment, the electrically conduc tive multilayer film is formed as a deformable struc ture so as to allow deforming of the electrically con ductive multilayer film along a three dimensional sur face. Said deforming may be based on, for example, stretchability of the electrically conductive multi layer film, and may be carried out, for example, by using thermoforming. Flexibility and/or deformability may have the added utility of enabling use of the electrically conductive multilayer film as a curved, or generally three dimensionally shaped structure, such as a dome shaped structure.

The embodiments described hereinbefore may be used in any combination with each other. Several of the embodiments may be combined together to form a further embodiment. An electrically conductive multi layer film, a method, a use, or a touch sensing de vice, to which the application is related, may com prise at least one of the embodiments described here inbefore. It will be understood that the benefits and advantages described herein may relate to one embodi ment or may relate to several embodiments. The embodi ments are not limited to those that solve any or all of the stated problems or those that have any or all of the stated benefits and advantages.

The electrically conductive multilayer film as described in this application has the added utility of having an improved adhesion of the transparent layer comprising transparent conductor material to the non-conductive base layer. The use of the transparent primer layer that is formed of a composition comprising a polymer, wherein the polymer is polyvinylidene chloride, a copolymer of vinylidene chloride, or a combination thereof, has the added utility of providing increased adhesion of the transparent layer comprising transparent conductor material to the non-conductive base layer thus simultaneously improving the electrical performance of the electrically conductive multilayer film. The use of the transparent primer layer as described in this application in the electrically conductive multilayer film as described in this application has the added utility of improving e.g. the environmental stability of the electrically conductive multilayer film making it more resistant to the effect of moisture and heat.

EXAMPLES

Reference will now be made in detail to the described embodiments, examples of which are illus trated in the accompanying drawings .

The description below discloses some embodi ments in such a detail that a person skilled in the art is able to utilize the method and the laminated film based on the disclosure. Not all steps of the em bodiments are discussed in detail, as many of the steps will be obvious for the person skilled in the art based on this specification.

For reasons of simplicity, item numbers will be maintained in the following exemplary embodiments in the case of repeating components.

Fig. 1 illustrates schematically a sectional view of an electrically conductive multilayer film 1 according to one embodiment described in this description. From Fig. 1 one can see an electrically conductive multilayer film 1 comprising a non- conductive base layer 2, a transparent layer comprising transparent conductor material 3, and a transparent primer layer 4. The non-conductive base layer 2, the transparent layer comprising transparent conductor material 3, and the transparent primer layer 4 are arranged one on the other in a vertical direction. The transparent primer layer 4 is situated between the non-conductive base layer 2 and the transparent layer comprising transparent conductor material 3. The transparent primer layer 4 may be in direct contact with the transparent layer comprising transparent conductor material 3. In one embodiment, the transparent primer layer 4 is also in direct contact with the transparent base layer 2. The transparent primer layer 4 is formed of a composition comprising a polymer, wherein the polymer is selected from a group consisting of polyvinylidene chloride, a copolymer, wherein one of the monomers is vinylidene chloride, and any combination thereof.

Fig. 2 illustrates schematically a sectional view of an electrically conductive multilayer film 1 as described in view of Fig. 1 with the addition that a transparent dielectric material forming a coating layer 5 is formed on the transparent layer comprising transparent conductor material. The thickness of the coating layer may be 10 - 600 nm.

The electrically conductive multilayer film 1 may comprise additional components thereon or attached thereto as will be clear to the skilled person even though these additional components are not illustrated in the accompanying figures.

Example 1 - Producing electrically conductive multilayer films

In this example an electrically conductive multilayer film, i.e. electrically conductive multilayer film 1, was produced by using the following materials:

The materials used for producing the electrically conductive multilayer film 1:

The PVDC co-polymer was a copolymer based on vinylidene chloride and vinyl chloride

In addition, a comparative electrically conductive multilayer film, i.e. comparative electrically conductive multilayer film Cl, was produced by using the following materials:

The materials used for producing the comparative electrically conductive multilayer film Cl:

Further, another comparative electrically conductive multilayer film C2 was produced by using the following materials:

The materials used for producing the comparative electrically conductive multilayer film C2 :

Firstly, the non-conductive base layers were provided. The thickness of the non-conductive base layer was 250 ym. Thereafter, the transparent primer layer was provided for producing the electrically conductive multilayer film 1 and the comparative electrically conductive multilayer film Cl. This was carried out by coating the non-conductive base layers with a composition of the selected polymer and a solvent (methyl isobutyl ketone (MIBK) ) using slot-die coating. The thickness of the formed transparent primer layers was in the range of 200 - 400 nm. After the slot-die coating, drying was carried out for about 10 minutes at a temperature of 100 °C .

The comparative electrically conductive multilayer film C2 was produced in an otherwise similar manner as the electrically conductive multilayer film 1 and the comparative electrically conductive multilayer film Cl, except that no transparent primer layer was formed between the non- conductive base layer and the transparent layer comprising transparent conductor material.

Then a transparent layer comprising transparent conductor material was provided on the transparent primer layer to be in direct contact with the transparent primer layer. The carbon nanobud molecules used in this example as the transparent conductor material can be synthesized from, for instance, a carbon source e.g. carbon monoxide using catalyst precursors such as ferrocene, or catalysts generated from a hot wire generator, such as metal particles and additional agents which, in addition to promoting the growth of nanobud molecules, increase the purity of the product. Details of the synthesis process can be found in publication WO 2007/057501 A1.

The carbon nanobud molecules were deposited as described in publication WO 2009/000969 on a nitrocellulose filter and then press transferred on the transparent primer layer, laying on the non- conductive base layer, to form a transparent layer comprising transparent conductor material thereon.

After the deposition the transparent conductor material was exposed to a solvent solution containing a gold chloride compound that was able to p-dope the carbon nanobud molecules (process step: p- doping) . After the p-doping, drying was carried out in an air circulated convection oven to improve bonding of the carbon nanobud molecules and to remove residual moisture (process step: drying).

Thereafter, contact pads of silver were printed by silk-screen printing on the transparent layer comprising transparent conductor material. The formed electrically conductive multilayer films were then allowed to dry for about 10 minutes at 100 °C (process step: silver contact printing).

Having produced the electrically conductive multilayer films as above described, the films were put through a TekNek contact cleaner with double sided elastomer rolls in order to remove dust and particles therefrom (process step: contact cleaning).

Thereafter, the three electrically conductive multilayer films were subjected to accelerated aging by keeping them at a temperature of 85 °C and at 85 % relative humidity for 72 hours (process step: accelerated aging) . The apparatus used was an environmental chamber of the model Weiss WKL 100.

Sheet resistance measurements

During the different process steps described above the sheet resistances (ohm/square) at the different process steps were measured using a four point probe (by Jandel Engineering Limited) before the accelerated aging and thereafter using the two silver contacts using an Agilent digital multimeter. For each measuring point a sample of 18 pieces of 30x30 mm CNB squares were used. The results can be seen in table 1.

Table 1. Results of measuring the sheet resistance during the different process steps during the production of the electrically conductive multilayer films

Based on the received test results it could be seen that film 1 is much more stable at high temperature and humidity than film Cl and film C2.

Adhesion test

The produced three electrically conductive multilayer films were thereafter subjected to an adhesion test in the following manner:

To evaluate the adhesion strength of the transparent layer comprising transparent conductor material on the non-conductive base layer (comparative film C2) or on the transparent primer layer (film 1 and film Cl), the sheet resistance (ohm/square) was first measured using a four point probe (by Jandel Engineering Limited) . Then a 3M scotch transparent film tape 600 was applied thereon by directly pressing the tape onto the transparent layer comprising transparent conductor material by using hand pressure. After 10 seconds of waiting time the tape was peeled off in a controlled motion and the sheet resistance (ohm/square) was re-measured to evaluate how much of the transparent conductor material was removed.

The results can be seen in table 2.

Table 2. Results from the adhesion test

Based on the received test results it could be seen that with the electrically conductive multilayer film 1 including the transparent primer layer formed by using the copolymer, good bonding strength of the transparent layer comprising transparent conductor material could be achieved compared to the comparative electrically conductive multilayer films. It is obvious to a person skilled in the art that with the advancement of technology, the basic idea may be implemented in various ways. The embodiments are thus not limited to the examples described above; instead they may vary within the scope of the claims.