WO2018104108A1

WO2018104108A1 - Composites comprising layers of nanoobjects and coating, preferably clear coating

Info

Publication number: WO2018104108A1
Application number: PCT/EP2017/080638
Authority: WO
Inventors: Byungil HWANG; Stefan Becker
Original assignee: Basf Se
Priority date: 2016-12-07
Filing date: 2017-11-28
Publication date: 2018-06-14
Also published as: TW201823035A

Abstract

Described are single or multiple layer composites, comprising a first layer of certain coating compositions or cured reaction products thereof, and an electrically conductive, transparent layer comprising a plurality of electrically conductive nanoobjects. The invention further relates to coated articles comprising base articles and coatings, where the coatings are single or multiple layer composites. The invention also relates to methods of making said single or multiple layer composites and said coated articles, as well as to the use of certain coating compositions for making scratch-resistant, transparent and electrically conductive single or multiple layer composites.

Description

Composites comprising layers of nanoobjects and coating, preferably clear coating

The present invention relates to single or multiple layer composites, comprising a first layer of certain coating compositions or cured reaction products thereof, and an electrically conductive, transparent layer comprising a plurality of electrically conductive nanoobjects. The invention further relates to coated articles comprising base articles and coatings, where the coatings are single or multiple layer composites. The invention also relates to methods of making said single or multiple layer composites and said coated articles, as well as to the use of certain coating compositions for making scratch-resistant, transparent and electrically conductive single or multiple layer composites.

Electrically conductive, transparent layers comprising pluralities of electrically conductive nanoobjects, e.g. layers comprising nanowires of metals, in particular of silver (Ag), are suitable for a variety of purposes. For example, such layers are or can be used in the manufacture of transparent electrodes, flat panel displays, liquid crystal displays (LCD), touch screens, electrochromic windows, solar cells, transparent or thin film heaters, smart glasses/spectacles, smart watches (including activity trackers), electronic wristbands, electronic textiles in general, triboelectricity nanoenergy generators and current collectors of batteries. Due to their small dimensions, yet substantially increased specific surface areas - compared e.g. to the corresponding bulk materials - electrically conductive, transparent layers comprising pluralities of electrically conductive nanoobjects and/or substrates carrying them can be susceptible to chemical, thermal and/or mechanical stress or dam- age. Said mechanical stress or damage can e.g. be caused by exposure to hard objects or by continued exposure to mechanical forces. Such exposures can occur during processes for the manufacture of said layers comprising electrically conductive nanoobjects, or thereafter, e.g. during conventional use of a product comprising such layers and/or substrates carrying them. Continued exposure to mechanical forces is e.g. common for transparent electrodes in touch screen applications. Mechanical damage or continued mechanical stress to the layers comprising electrically conductive nanoobjects and/or to substrates carrying them, usually appearing as scratches, may affect proper functioning of such layers or of products comprising them. E.g. such mechanical damage to the layers comprising electrically conductive nanoobjects may result in deterioration of their electrical conductivity and/or their optical properties. Mechanical damage to the substrates carrying said layers comprising electrically conductive nanoobjects may also result in deterioration of the said layers' optical properties.

In patent US 8,049,333 a transparent conductor is described, including a conductive layer comprising a network of nanowires which may be embedded in a matrix. The conductor can further comprise hard coats for providing protection against i.a. scratches. Suitable hard coats can include synthetic polymers.

C.-H. Liu et al (Nanoscale Research Letters 201 1 , 6:75) describe Ag nanowire-based transparent and conductive films. Using nail polish, Ag nanowire films showed better stability under both scratching and bending. Document WO 2014/137352 A1 describes a process for providing metallic substrates with corrosion resistance.

Document US 2014/0277318 A1 pertains to an implantable electrode comprising a conductive polymeric coating.

Document DE 102006024823 A1 (equivalent to US 2009/0223631 A1 ) describes the use of curable mixtures comprising silane compounds and phosphonic diesters or disphos- phonic diesters as coupling agents. Document WO 2006/122730 A1 describes a coating substance for in-mould-coating on the basis of an aminofunctional reactant for isocyanates and a method for the production thereof.

It was a primary object of the present invention to provide single or multiple layer compo- sites comprising electrically conductive, transparent layers comprising pluralities of electrically conductive nanoobjects, where said electrically conductive, transparent layers comprising pluralities of electrically conductive nanoobjects are effectively protected against mechanical damage, in particular against scratches. It was a further object of the invention to provide said single or multiple layer composites in a transparent and clear appearance. A yet further object of the invention was to provide said single or multiple layer composites in a flexible form, in particular in a flexible form which allows mechanical manipulation without damaging said composites.

It was another object of the present invention to provide coated articles comprising said single or multiple layer composites. It was yet another object of the invention to provide methods of making said single or multiple layer composites.

It was also an object of the present invention to provide a new use of certain coating compositions for making scratch-resistant, transparent and electrically conductive single or multiple layer composites. The invention as well as preferred embodiments thereof are defined in the claims. The invention and its embodiments and preferred embodiments are also described and explained in more detail here below. If not indicated otherwise, preferred embodiments and/or preferred aspects of the invention can be combined with other embodiments and/or aspects of the invention as described herein, in particular with other preferred embodiments and/or preferred aspects. Combinations of preferred embodiments and/or preferred aspects with other preferred embodiments and/or preferred aspects of the invention will usually also result in preferred embodiments and/or preferred aspects of the invention.

Embodiments, aspects and/or characteristics which are described or set forth herein with respect to the single or multiple layer composites of the invention, or which are described or set forth in this respect as preferred, shall also be applicable mutatis mutandis with respect to the coated articles of the invention, the methods of making of the invention of said single or multiple layer composites and/or the uses of the invention of certain coating compositions, if not stated otherwise.

Where single or multiple layer composites, coated articles, methods of making or uses of the invention are described herein which are "comprising" or "containing" certain further defined embodiments, elements, features and/or parameters, this broader definition shall in each case also comprise the disclosure of the narrower alternatives which are "consisting of" said embodiments, elements, features and/or parameters, if not stated otherwise.

It has now been found that the primary object and other objects of the invention are accomplished by a single or multiple layer composite, comprising i) a first layer comprising a coating composition comprising

(a) at least one binder (A) having reactive groups, which is a hydroxyl- containing compound (A),

(b) at least one crosslinking agent (B) which is able to react, with crosslinking with the reactive groups of the binder (A), which is a compound (B) having free and/or blocked isocyanate groups and

(c) at least one catalyst (C) for the crosslinking of silane groups, which is a

phosphoric acid compound, more particularly phosphoric acid or phosphonic acid, which is blocked with a bicyclic amine having a pKb > 3 and a boiling point > 100°C, where one or more constituents (A) and/or (B) and/or at least one further constituent of the coating composition contain hydrolysable silane groups, or a cured reaction product thereof, and ii) an electrically conductive, transparent layer comprising a plurality of electrically conductive nanoobjects, wherein said first layer and said electrically conductive, transparent layer (also referred to as "nanoobject layer" in the following) are the same or different. Specific coating compositions and cured products thereof as used in the present invention are known per se. Specific coating compositions are e.g. disclosed in documents EP 2225299B1 ; WO 2009/077180 and US 8,808,805, which documents and their disclosures are all incorporated herein by reference in their entireties.

In the coating compositions according to the invention, the at least one catalyst (C) for the crosslinking of silane groups is a phosphoric acid compound, preferably a phosphoric acid, which is blocked with a bicyclic amine having a pKb > 3 and a boiling point > 100°C. Preferred are coating compositions of the present invention wherein catalyst (C) is selected from the group consisting of substituted phosphoric monoesters and phosphoric diesters blocked with a bicyclic amine having a pKb > 3 and a boiling point > 100°C, preferably from the group consisting of acyclic phosphoric diesters and cyclic phosphoric diesters blocked with a bicyclic amine having a pKb > 3 and a boiling point > 100°C. More preferably the catalyst (C) is selected from the group consisting of amine-blocked phosphoric acid ethylhexyl partial esters and amine-blocked phosphoric acid phenyl partial esters, and even more preferably the catalyst (C) is selected from the group consisting of amine-blocked phosphoric acid bis(ethylhexyl) esters. In one particularly preferred variant of the present invention, the blocking bicyclic amine present in the catalyst (C) is diazabicyclooctane.

Further, coating compositions of the present invention are preferred wherein one or more constituents of the coating composition at least partly contain one or more, identical or different structural units of the formula (I)

-X-Si-R"_XG₃-_X (I) with

G is/are identical or different hydrolysable groups, more particularly (i.e. highly

preferably) G is an alkoxy group (O R'), X is an organic radical, more particularly linear and/or branched alkylene or cycloalkylene radical having a total number of 1 to 20 carbon atoms, very preferably X is an alkylene radical having a total number of 1 to 4 carbon atoms,

R" is alkyl, cycloalkyl, aryl, or aralkyl, it being possible for the carbon chain to be interrupted by nonadjacent oxygen, sulfur or NR_a groups, with R_a is alkyl, cycloalkyl, aryl or aralkyl, preferably R" is an alkyl radical, more particularly having a total number of 1 to 6 carbon atoms, and x is 0 to 2, preferably 0 to 1 , more preferably x is 0.

In the group or groups G, the substituent R' is preferably an alkyl radical having a total number of 1 to 6, preferably of 1 to 4, carbon atoms. Alkoxy groups OR' in the group or groups G are identical or are different. Preferred are groups G wherein the alkoxy groups OR' are identical.

A more detailed description and definition of suitable coating compositions, their preferred embodiments and methods of producing coatings, preferably clear coatings, from said coating compositions is given in EP 2 225 299 B1 ; WO 2009/077180 and/or US 8,808,805. Preferred coating compositions for use in a single or multiple layer composite of the present invention are defined in claims 3, 4, 6, 7, 8, 9, 10, 1 1 , 12, and 13 of EP 2 225 299 B1 ; these definitions are incorporated herein by reference. Also preferred are the cured reaction products (i.e., coatings) of preferred coating compositions as defined above.

Coatings, preferably clear coatings produced from said coating compositions are to be regarded as cured reaction products of said coating compositions. Preferred coating compositions for use according to the present invention are commercially available from BASF under the trademark "iGloss".

The term "nanoobjects" as used herein is meant to denote objects with one, two or three of their external dimensions being in the nanoscale. Definitions as used herein to further describe and explain terms related to nanotechnologies are referring to standard technical specification ISO/TS 27687:2008 (first ed.). "Nanoscale" as used herein is therefore meant to comprise the size range of from about 1 to 100 nm. Nanoscale dimensions can be determined for the purposes of the present invention by means of transmission electron microscopy ("TEM"), known in the art. E.g. the thickness of layers comprised by the single or multiple layer composite of the invention can be determined from TEM images of the cross-section of a sample from said layer or said composite, respectively. Nanoscale dimensions can also be determined for the purposes of the present invention by scanning electron microscopy ("SEM"), e.g. by a field-emission scanning electron microscope, as known in the art. Samples for studying the cross-section(s) can be prepared by means of focused ion beam ("FIB") technology, as is known in the art. Nanoobjects as used herein are electrically conductive and preferably comprise or consist of a material which has a high conductivity, preferably a material which has a conductivity of no less than 1 x 10⁵ S/m at 20 °C. Nanoobjects can be selected for the purposes of the present invention from the group consisting of nanoparticles, nanoplates, nanoflakes, nanofibres, nanotubes, nanorods, nanospheres, nanoribbons and nanowires. Nanowires are preferred, in particular where the nanoobjects comprise or consist of metals or their alloys. Nanotubes are preferred, in particular where the nanoobjects comprise or consist of carbon. The term "nanoparticle" as used herein is meant to denote a nanoobject with all three external dimensions being in the nanoscale, while the length of the longest axis and the length of the shortest axis of said nanoobject do not differ significantly.

The term "nanoplate" as used herein is meant to denote a nanoobject with one of its external dimensions being in the nanoscale while the two other external dimensions may be significantly larger (e.g. larger by three times or more) and not necessarily be in the nanoscale. The smallest external dimension is regarded as the thickness of the nanoplate. Another common term often used to denote nanoobjects which have only one dimension in the nanoscale is "nanoflakes".

The term "nanofiber" as used herein is meant to denote a nanoobject with two similar external dimensions in the nanoscale and the third dimension being significantly larger. The two similar external dimensions are considered to differ in size by less than three times and the one significantly larger external dimension is considered to differ from the other two by three times or more and may not necessarily be in the nanoscale. Said largest external dimension corresponds to the length of the nanofiber. Nanofibers can be flexible or rigid.

The term "nanotubes" as used herein is meant to denote a nanofiber which is hollow. The term "nanorod" as used herein is meant to denote a nanoobject with two similar external dimensions in the nanoscale and the third dimension being significantly larger and which is rigid (i.e. not flexible). Nanorods can be regarded as solid (or rigid) nanofibers. The term "nanospheres" as used herein is meant to denote approximately isometric nanoparticles, i.e. nanoparticles where the aspect ratios of all three orthogonal external dimensions are close to 1. The aspect ratio denotes the ratio of the longest to the shortest dimension of an object (usually the ratio of height : length).

The term "nanoribbons" as used herein is meant to denote nanoobjects having two similar external dimensions in the nanoscale, while the third external dimension (length) is significantly larger. Nanoribbons have a nearly rectangular-shaped cross-section extending the third external dimension (length) perpendicularly.

The term "nanowire" as used herein is meant to denote an electrically conductive or semi- conductive nanofibre, preferably an electrically conductive nanofiber. The term "electrically conductive" as used herein generally has the meaning that a material with this property is capable of allowing the flow of an electric current when an appropriate voltage is applied. The electrically conductive, transparent layer comprised by the single or multiple layer composite of the invention comprises a plurality of electrically conductive nanoobjects. Said electrically conductive nanoobjects partly contribute to, preferably contribute to, and more preferably fully establish the electrically conductive properties of said electrically conductive, transparent layer. The nature of the electrically conductive nanoobjects, their number and their arrangement in the electrically conductive, transparent layer must be selected in a way so as to allow for, increase and/or determine the electrical conductivity of the electrically conductive, transparent layer. With respect to the electrically conductive nanoobjects, preferably the electrically conductive metal nanoobjects, as used in the present invention, "electrically conductive" preferably has the meaning that the respective nanoobjects have (respectively the material of which the electrically conductive nanoobjects are made has) a conductivity of no less than 1 x 10⁵ S/m at 20 °C, preferably in the range of from 1x 10⁵ to 1x 10⁹ S/m at 20 °C. With respect to the electrically conductive, transparent layer comprising a plurality of electrically conductive nanoobjects, electrical conductivity can best be provided in terms of its "sheet resistance" (see below for details). Preferably, the electrically conductive, transparent layer comprising a plurality of electrically conductive nanoobjects has a sheet resistance in the range of from 10 to 150 ohm/sq, more preferably of from 10 to 60 ohm/sq, as measured by the four point probe, or by a non-contact-type sheet resistance measurement system (inductive measurement), on the respective surface of said electrically conductive, transparent layer comprising a plurality of electrically conductive nanoobjects. Preferably, the sheet resistance of a single or multiple layer composite of the invention is measured by non-contact-type sheet resistance measurement as defined in more detail below, more preferably according to standard procedure ASTM F1844 - 97 (2016). Electrical conductivity is present in one or more directions and/or areas of the electrically conductive, transparent layer, and typically is at least present within said layer in a direction and/or in one or more areas parallel to the surface of the layer itself.

With respect to the single or multiple layer composites of the invention, electrical conductivity can likewise best be provided in terms of their "sheet resistances" (see below for details). Preferably, the single or multiple layer composites of the invention have sheet resistances in a range of from 10 to 150 ohm/sq, more preferably of from 10 to 60 ohm/sq, as measured by a non-contact-type sheet resistance measurement system as defined in more detail below (inductive measurement) on the surface of said first layer of said single or multiple layer composites. Preferably, the sheet resistance of a single or multiple layer composite of the invention is measured by non-contact-type sheet resistance measurement according to standard procedure ASTM F1844 - 97(2016).

The electrically conductive nanoobjects, in particular the nanowires, of the present invention can comprise or consist of one or more metals (also referred to as "metal nanoobjects" or "metal nanowires", as applicable) and/or of one or more non-metallic materials, including mixtures of one or more metallic (like e.g. Ag) and one or more non- metallic (like e.g. carbon) materials.

Suitable one or more metals which are comprised by the electrically conductive metal nanoobjects of the present invention or of which the electrically conductive metal nanoobjects of the present invention consist are selected from the group consisting of cobalt (Co), copper (Cu), gold (Au), iron (Fe), molybdenum (Mo), nickel (Ni), palladium (Pd), silver (Ag), tin (Sn), tungsten (W) and - where possible - alloys made of two or more of said metals. Preferred metals are Ag, Au, Cu and Ni and any alloys made of two or more of said metals. Pure metals are preferred over alloys. Most preferred is Ag. A suitable non-metallic material for electrically conductive nanoobjects is carbon, in particular in the form of graphene and/or in the form of carbon nanotubes.

Metal nanoobjects, in particular metal nanowires, more in particular Ag nanowires, are preferred electrically conductive nanoobjects with respect to all aspects of the present invention (single or multiple layer composites, coated articles, methods of making and uses).

Preferably the above-defined electrically conductive nanoobjects are metal nanowires, more preferred metal nanowires having in each case an average length (without any coating or adsorptive agent on their external surfaces) in a range of from 10 μιη to 50 μιη, preferably an average length in a range of from 15 μιη to 40 μιη, more preferred an average length in a range of from 20 μιη to 30 μιη, e.g. a length of about 25 μιη, and in each case an average diameter in the range of from 10 nm to 100 nm, preferably an average diameter in the range of from 15 nm to 80 nm, more preferred an average diameter in the range of from 20 nm to 50 nm, e.g. a diameter of about 30 nm. Generally, electrically conductive nanoobjects as described herein and methods for preparing them are both known in the art (see e.g. US 7,922,787 or US 8,049,333 and references cited therein in each case). Moreover, many of said electrically conductive nanoobjects are commercially available, in particular metal nanowires like Au or Ag nanowires. Typical commercial presentations are e.g. alcoholic or aqueous dispersions of e.g. Ag or Au nanowires, wherein suitable preservatives may be used which are coated or adsorbed to the surfaces of said nanowires, e.g. polyvinylpyrrolidone or polyethylene glycol.

Non-metallic electrically conductive nanoobjects like carbon nanotubes, and methods for their preparation and use are known in the art, see e.g. US 6,232,706, R. Chavan et al., International Journal of Pharmaceutical Sciences Review and Research, Vol. 13/1 (2012) 125-134 or K. Saeed et al., Carbon Letters Vol. 14/3 (2013) 131-144. Carbon nanotubes are also commercially available, e.g. from Sigma-Aldrich, see e.g. brochure by Sigma- Aldrich Co. "Material Matters" Vol. 4 No. 1 (2009).

Preferred is a single or multiple layer composite according to the invention as defined herein (or a single or multiple layer composite according to the invention as defined herein as preferred), comprising i) a first layer comprising a coating composition comprising

(c) at least one catalyst (C) for the crosslinking of silane groups, which is a phosphoric acid compound, selected from the group consisting of substituted phosphoric monoesters and phosphoric diesters, preferably from the group consisting of acyclic phosphoric diesters and cyclic phosphoric diesters, which is blocked with a bicyclic amine having a pKb > 3 and a boiling point > 100°C, where one or more constituents (A) and/or (B) and/or at least one further constituent of the coating composition contain hydrolysable silane groups, or a cured reaction product thereof, and ii) an electrically conductive, transparent layer comprising a plurality of electrically conductive metal nanoobjects, wherein the metal is preferably selected from the group consisting of cobalt, copper, gold, iron, molybdenum, nickel, palladium, silver, tin, tungsten and alloys made of two or more of said metals, and wherein said first layer and said electrically conductive, transparent layer are the same or different. Preferably, the "electrically conductive, transparent layer" is an electronically conductive, transparent layer (as opposed to "ionically conductive"). Likewise, preferably the "electrically conductive nanoobjects" are electronically conductive nanoobjects. Preferably, the "electrically conductive, transparent layer comprising a plurality of electrically conductive nanoobjects" is an electronically conductive, transparent layer comprising a plurality of electronically conductive nanoobjects. Most preferably, in such an electronically conductive, transparent layer comprising a plurality of electronically conductive nanoobjects at least 90 % of the total electrical conductivity of the electronically conductive, transparent layer is caused by the presence of said plurality of electronically conductive nanoobjects. The terms "transparent", "transparency" or "optically transparent" as used herein, in particular with respect to the transparence or light transmission of a layer of the single or multiple layer composite of the invention preferably have the meanings that said layer (i.e.: each transparent layer), e.g. the electrically conductive, transparent layer comprising a plurality of electrically conductive nanoobjects, has a light transmission of 70 % or more, more preferred of 75 % or more, yet more preferred of 80 % or more, even more preferred of 85 % or more and yet even more preferred of 90 % or more, in each case in the visible region of the electromagnetic spectrum, i.e. in a range of from about 380 nm to 780 nm, more in particular in a range of from about 400 to 700 nm, when measured in each case according to standard method ASTM D1003-13 (procedure A). In a preferred embodiment, the first layer as defined above is transparent and clear and more preferably said first layer is in the form of a transparent clear coating.

In another preferred embodiment, the single or multiple layer composite of the invention exclusively comprises transparent layers and preferably is transparent itself.

As will be understood, the light transmission capacity of each layer is i.a. a function of its thickness and its material. The overall light transmission capacity of a transparent single or multiple layer composite of the invention is i.a. a function of the thickness, material and/or number of the layers forming it. Generally, the single or multiple layer composite of the invention may comprise one, two or more layers (including e.g. three, four or five layers). However, in those preferred embodiments of the invention where a transparent single or multiple layer composite is desired, this will exclusively comprise transparent layers and only in such number and thickness as to allow for transparency of the entire single or multiple layer composite. Preferably, the single or multiple layer composite of the invention does not comprise more than one of each of (i) first layer and (ii) electrically conductive, transparent layer comprising a plurality of electrically conductive nanoobjects as well as, if at all present, substrate layer.

In a further preferred embodiment, the single or multiple layer composite of the invention is flexible. The term "flexible" as used herein means that a material with this property can be bent (but not necessarily folded) in all directions without experiencing damage to its structure, while maintaining all or at least a part of its optical and/or electrical properties. Those skilled in the art will understand the level of mechanical stress that can reasonably be applied when manipulating electronic components like the single or multiple layer composite of the invention. Preferred is a single or multiple layer composite that is a single or multiple layer composite film, preferably in the form of a roll film.

In certain preferred embodiments, the single or multiple layer composite of the invention can further comprise one or more substrate layers, effectively resulting in a multiple layer composite (i.e. at least two-layer composite) of the invention.

Preferably, a substrate layer as used in a single or multiple layer composite of the present invention is in a form selected from the group consisting of foils, films, webs, panes and plates. Further preferred are substrate layers which have a thickness in a range of from 5 μιη to 250 μιη, preferably in a range of from 10 μιη to 200 μιη, more preferably in the range of from 50 μιη to 100 μιη, in each case perpendicular to an interface of the substrate layer. Where flexible single or multiple layer composites are desired, the substrate layers are typically also flexible per se.

The substrate layer or layers preferably comprise or consist of one or more materials selected from the group consisting of glass, metals, sapphire, silicon (Si) and plastics, unless otherwise stated.

In specific and preferred cases, in particular where transparent single or multiple layer composites are desired, said substrate layer or layers comprise or consist of a transparent material. Preferably, said substrate layers in these cases are also electrically insulating. Suitable transparent materials for substrate layers can e.g. be selected from the group consisting of glass and plastics. Preferred types of glass are e.g. float glass, low iron float glass, heat strengthened glass and chemically strengthened glass. Optionally, the glass has a low-emissivity (low-e) coating, sun-protection coating or any other coating on the surface facing away from the above-described nanoobject layer ii). Preferred types of plastics are organic polymers, more preferably organic polymers selected from the group consisting of polymethylmethacrylate (PMMA, commercially available e.g. as Plexiglas™), polycarbonate (PC), polyethylene (PE), low density polyethylene (LDPE), linear low density polyethylene (LLDPE), polypropylene (PP), low density polypropylene (LDPP), polyethylene terephthalate (PET), glycol modified polyethylene terephthalate, polyethylene naphthalate (PEN), cellulose acetate butyrate, polylactide (PL), polystyrene (PS), polyvinyl chloride (PVC), polyiimides (PI), polypropyleneoxide (PPO) and mixtures of any of the foregoing organic polymers. PET and PEN are particularly preferred.

Preferably, a substrate layer as used in an embodiment of the present invention (i.e. as used in a single or multiple layer composite according to the invention) is flexible. Further, a substrate layer as used in an embodiment of the present invention is preferably transparent. Still further, a substrate layer as used in an embodiment of the present invention preferably has a surface which shows appropriate hardness, in particular resistance against mechanical stress, and more preferably is scratch-resistant. Moreover, a substrate layer as used in an embodiment of the present invention preferably has a low moisture permeability and/or high thermal resistance. A substrate layer as used in an embodiment of the present invention preferably comprises or consists of organic polymers as defined above. An appropriate hardness of a surface of a substrate layer as used in an embodiment of the present invention is in a range of 1 H to 9H, more preferred in the range of from 2H to 4H, in each case as measured according to the pencil standard test method for film hardness, ASTM D3363-00.

As explained above, the single or multiple layer composite of the invention comprises said first layer i) and said nanoobject layer ii), wherein said first layer and said nanoobject layer can be the same or different.

In one preferred embodiment of said single or multiple layer composite, said first layer and said nanoobject layer are the same, and the concentration of electrically conductive nanoobjects in the first layer has a gradient in a direction perpendicular to an interface of the layer or the concentration of electrically conductive nanoobjects in the first layer is the same in all directions of the layer. The alternative where the concentration of electrically conductive nanoobjects in the first layer has a gradient is preferred and can preferably be obtained by first creating a nanoobject layer and subsequently embedding said nanoobject layer in a matrix material, thus creating said first layer as a single layer, e.g. as further described below. In one preferred option of this alternative the above-defined plurality of electrically conductive nanoobjects, more preferably a plurality of metal nanoobjects and/or metal nanowires, is arranged in the nanoobject layer in the form of an electrically conductive network of adjacent and contacting metal nanoobjects or metal nanowires, respectively, with sufficient interconnection (i.e. mutual contact) between individual electrically conductive nanoobjects or electrically conductive nanowires, preferably metal nanoobjects or metal nanowires, so as to enable a flow of electrons along the interconnected electrically conductive nanoobjects or electrically conductive nanowires, preferably metal nanoobjects or metal nanowires, within the network. Where such network is built of electrically conductive nanowires, it will also be referred to as "nanowire network" (or "metal nanowire net- work", respectively) herein. In one particularly preferred option of this alternative, a plurality of electrically conductive nanowires in the electrically conductive, transparent layer is embodied by a network of silver nanowires ("AgNWs").

The alternative where the concentration of electrically conductive nanoobjects in the first layer is the same in all directions of the layer can preferably be obtained by pre-mixing a suitable preparation of metal nanoobjects, e.g. a suitable preparation of metal nanowires like AgNWs, with at least one suitable component of the above-defined coating composition, preferably until a homogeneous distribution is reached in the pre-mixture, and using this (preferably homogeneous) pre-mixture for further processing, e.g. as further described below. To facilitate electrical conductivity in the resulting nanoobject layer, the concentration of electrically conductive nanoobjects in the pre-mixture can be adjusted to a suitable value.

In preferred embodiments of the single or multiple layer composite of the invention, said first layer (i)) has a thickness of not more than 30 μιη, preferably a thickness in the range of from 0.1 to 30 μιη, more preferably a thickness in a range of from 0.1 to 10 μιη, in each case perpendicular to an interface of the first layer. This embodiment is particularly preferred where said first layer and said nanoobject layer are the same. This embodiment is also particularly preferred where said first layer and said nanoobject layer are the same and wherein the concentration of electrically conductive nanoobjects in the first layer has a gradient in a direction perpendicular to an interface of the layer. In some embodiments of the single or multiple layer composite of the invention, said first layer (i)) has a thickness of not more than 500 μιη, preferably a thickness in the range of from 20 to 150 μιη, in each case perpendicular to an interface of the first layer. This embodiment is particularly preferred where said first layer and said nanoobject layer are different.

In multiple layer composites of the invention where said first layer i) and said nanoobject layer ii) are the same and the composite further comprises a substrate layer, the combined first and nanoobject layer may be arranged on a surface of said substrate in such manner that it extends over the complete surface of said substrate, or only within limited regions of said surface. In specific cases, the plurality of electrically conductive nanoobjects in the combined first and nanoobject layer forms a pattern on said surface of said substrate. The pattern may be selected from any random and non-random structures, like grids, stripes, waves, dots and circles.

In another preferred embodiment, the single or multiple layer composite of the invention is a multiple layer composite, wherein said first layer and said electrically conductive, transparent layer comprising a plurality of electrically conductive nanoobjects are different and wherein said first layer and said electrically conductive, transparent layer are separated from each other by one or more substrate layers. Preferred are single or multiple layer composites of this embodiment which comprise not more than one layer of each type, first layer; electrically conductive, transparent layer comprising a plurality of electrically conductive nanoobjects and substrate layer.

In an alternative of this embodiment, the nanoobject layer may be arranged on a surface of said substrate in such manner that it extends over the complete surface of said substrate, or only within limited regions of said surface. In specific cases, the plurality of electrically conductive nanoobjects in the nanoobject layer forms a pattern on said surface of said substrate. The pattern may be selected from any random and non-random structures, like grids, stripes, waves, dots and circles.

The present invention also relates to a coated article, said article comprising a base article, and a coating on the base article, wherein the coating is a single or multiple layer composite of the present invention as defined herein or a single or multiple layer composite of the present invention as defined herein as preferred.

Generally, all aspects of the present invention discussed herein in the context of the inventive single or multiple layer composite apply mutatis mutandis to the coated article according to the present invention, as defined here above and below, and vice versa.

Said coated article can e.g. be an intermediate product in the manufacture of, or, as applicable, can be a product or a part of a product selected from the group comprising transparent electrodes, flat panel displays, liquid crystal displays (LCD), touch screens, electrochromic windows, solar cells, transparent or thin film heaters, smart glasses/spectacles, smart watches (including activity trackers), electronic wristbands, electronic textiles in general, triboelectricity nanoenergy generators and current collectors of batteries.

The present invention further relates to a method of making a single or multiple layer composite as defined herein or a coated article as defined herein, the method comprising the following steps: providing or preparing a coating composition, said coating composition comprising

(a) at least one binder (A) having reactive groups, which is a hydroxyl-containing compound (A),

(c) at least one catalyst (C) for the crosslinking of silane groups, which is a phosphoric acid compound, more particularly phosphoric acid or phosphonic acid, which is blocked with a bicyclic amine having a pKb > 3 and a boiling point > 100°C, preferably a phosphoric acid compound selected from the group consisting of substituted phosphoric monoesters and phosphoric diesters, which is blocked with a bicyclic amine having a pKb > 3 and a boiling point > 100°C, where one or more constituents (A) and/or (B) and/or at least one further constituent of the coating composition contain hydrolysable silane groups, providing or preparing a mixture comprising a plurality of electrically conductive nanoobjects and applying said coating composition and said mixture to a single (preferably the same) surface or to at least two different surfaces (preferably said coating composition and said mixture are applied to the same of the at least two surfaces in each of the cases) of a substrate, o in a single step after pre-mixing of said coating composition with said mixture or o in separate steps without pre-mixing of said coating composition with said mixture.

As stated above, preferred methods of producing coatings, preferably clear coatings, from coating compositions are explained and disclosed in more detail in documents EP 2225299B1 ; WO 2009/077180 and US 8,808,805, incorporated herein by reference.

Generally, all aspects of the present invention discussed herein in the context of the inventive single or multiple layer composite and the coated article apply mutatis mutandis to the method of making according to the present invention, as defined here above and below, and vice versa.

In one preferred embodiment of said method of making of the present invention, said coating composition and said mixture comprising a plurality of electrically conductive nanoobjects, without pre-mixing, are applied to a single (i.e. at least one, preferably the same) surface of a substrate in separate steps, wherein - in a first application step said mixture comprising a plurality of electrically conductive nanoobjects is applied to the surface of the substrate and subsequently in a second application step said coating composition is applied o onto the mixture on the surface of the substrate or o onto the plurality of electrically conductive nanoobjects on the surface of the substrate, so that a first, electrically conductive, transparent layer comprising a plurality of electrically conductive nanoobjects is created on the substrate, wherein preferably

(aa) the first layer on the surface has a thickness of not more than 30 μιη, preferably a thickness in the range of from 0.1 to 10 μιη, perpendicular to an interface of the layer and/or

(ba) the concentration of electrically conductive nanoobjects in the first layer has a gradient in a direction perpendicular to an interface of the layer.

Said first application step and said second application step can be carried out as many times as desired in order to create as many first, electrically conductive, transparent layers comprising a plurality of electrically conductive nanoobjects as desired. Preferably, each of the first application step and second application step is only carried out once so that only one first, electrically conductive, transparent layer comprising a plurality of electrically conductive nanoobjects is created.

In this preferred embodiment of said method of making, a single or multiple layer composite can be prepared wherein said first layer i) and said nanoobject layer ii) are the same and where the concentration of electrically conductive nanoobjects, preferably of metal nanoobjects, in the combined first layer and nanoobject layer has a gradient in a direction perpendicular to an interface of the layer. Preferably, the electrically conductive nanoobjects are embedded in this case in the first layer and at least a portion of said electroconductive nanoobjects are exposed on a surface or interface of said first layer, i.e. in a way to provide electrical contact.

Where metal nanoobjects, more preferably metal nanowires, are used in a method of the present invention, the mixture comprising a plurality of metal nanoobjects is preferably provided or prepared in a way known in the art, e.g. by first depositing a plurality of un- coated metal nanoobjects on a surface of a substrate, so that metal-metal junctions between adjacent and overlapping (contacting) metal nanoobjects are formed. Typically, said plurality of metal nanoobjects is applied to said surface of said substrate in the form of a suspension (sometimes referred to as an ink) comprising metal nanoobjects, dis- persed in a carrier liquid. The carrier liquid usually has a boiling point below 120 °C. Commonly used carrier liquids are e.g. ethanol, isopropyl alcohol (propan-2-ol), water or mixtures of any of the foregoing. Thus, disposing a plurality of metal nanoobjects on a surface of a substrate in this alternative is usually carried out by: forming on a surface of said substrate a wet film by applying a suspension of metal nanoobjects dispersed in a carrier liquid to said surface of said substrate and removing said carrier liquid from the wet film formed on said surface of said substrate.

Preferably said ink is applied to said surface of said substrate by a technique selected from the group consisting of coating and printing techniques. Preferred techniques are selected from the group consisting of (doctor) blade coating, slot-die coating, ink-jet printing, spin-coating and spray-coating (including air spraying and electrostatic spraying).

Said carrier liquid having a boiling point of less than 120 °C is usually removed from the wet film by evaporation (drying). Preferably, said carrier liquid having a boiling point of less than 120 °C is removed by exposing the wet film formed on said surface of said substrate to air having a temperature of less than 150 °C, preferably at a temperature in the range of from 20 °C to 120 °C, e.g. at about 120 °C. In some cases, the carrier liquid is removed at room temperature, i.e. at a temperature in the range of 20 to 23 °C.

Preferably, the coverage of the surface of said substrate by said plurality of metal nano- objects is in the range of from 10 % to 65 %, preferably in the range of from 15 % to 35 %. For calculating the coverage, images of the surface having said plurality of metal nanoobjects disposed thereon are taken by optical microscopy or scanning electron microscopy, and the images are analyzed by means of an image analyzing software capable of differentiating within said images said metal nanoobjects from the bare surface of the substrate and calculating the fraction of the surface covered by the metal nanoobjects, as is known in the art. The thickness of a resulting layer comprising a plurality of electrically conductive nanoobjects, preferably metal nanoobjects, but not yet a coating composition as defined above, is usually in a range of from 10 to 150 nm, preferably in a range of from 20 to 100 nm.

After depositing said plurality of metal nanoobjects on said surface of said substrate, said coating composition is preferably applied onto the plurality of metal nanoobjects previously prepared. It is assumed that deposition of the coating on the plurality of metal nanoobjects does not significantly alter the junctions between adjacent and overlapping (mutually contacting) metal nanoobjects of said plurality of metal nanoobjects disposed on said surface of said substrate. Applying said coating composition onto the plurality of metal nanoobjects can preferably be carried out according to the general methods disclosed in any of documents EP 2225299B1 ; WO 2009/0777180 and/or US 8,808,805, as discussed above.

In the coating composition employed according to the present invention (in particular, single or multiple layer composite of the invention or method of making), the weight fractions of the polyol (A) and of the polyisocyanate (B) are preferably selected such that the molar equivalent ratio of the unreacted isocyanate groups of the isocyanate- containing compounds (B) to the hydroxyl groups of the hydroxyl-containing compounds

(A) is in a range of from 0.9: 1 to 1 : 1.1 , preferably in a range of from 0.95: 1 to 1.05: 1 , more preferably in a range of from 0.98: 1 to 1.02: 1. A coating component comprising the hydroxyl-containing compound (A) and optionally also further components (as described in more detail in e.g. US 8,808,805) is typically mixed with a further coating component comprising the isocyanato-containing compound

(B) and, where appropriate, further of the optional components as described: this mixing is typically conducted shortly before the resulting coating composition is applied. General- ly speaking, the coating component that comprises the compound (A) typically also comprises the catalyst (C) and also part of the solvent. Solvents suitable for the coating compositions of the invention are in particular those which, in the coating composition, are chemically inert toward the compounds (A) and (B) and also do not react with (A) and (B) when the coating composition is being cured (see e.g. US 8,808,805 for more details). The coating composition can be applied onto the plurality of metal nanoobjects by any coating method selected from the group consisting of (doctor) blade coating, slot-die coating, ink-jet printing, spin-coating and spray-coating (including air spraying and electrostatic spraying). Any solvent present can subsequently be removed, partially or completely, preferably by evaporation. E.g. the solvent can be evaporated by exposure to air or compressed air for a period in a range of from 10 to 60 min., like e.g. 20 min.

The applied coating compositions can subsequently be cured or annealed into a finished coating, preferably into a clear or transparent coating, preferably after removal of the solvent and (where necessary) a certain additional rest time (usually a time period not exceeding 1 h). Such rest time serves, for example, for the leveling and devolatilization of the coating films and/or for evaporation of volatile constituents such as solvents. The rest time may be assisted and/or shortened by the application of elevated temperatures and/or by a reduced humidity, provided this does not entail any damage or alteration to the coating films, such as e.g. premature complete crosslinking. The thermal curing of the coating compositions is usually not critical in terms of the method to be applied and common methods known in the art can be used like heating in a forced-air oven or irradiation with infrared lamps. The thermal cure may also take place in stages. Another preferred curing method is that of curing with near infrared (NIR) radiation. The thermal cure is preferably carried out at a temperature in the range of from 30 to 200 °C, more preferably in a range of from 40 to 190° C, in particular in a range of from 50 to 180° C like 140 °C, in each case for a time period in a range of from 1 min to 10 h, more preferably in the range of from 2 min to 5 h, and even more preferably in a range of from 3 min to 3 h, e.g for a time period of from 5 min to 60 min, like 20 min. In an embodiment of said method of making of the present invention, said coating composition and said mixture comprising a plurality of electrically conductive nanoobjects, after pre-mixing, are applied to at least one surface of a substrate, wherein said mixture comprising a plurality of electrically conductive nanoobjects is first pre- mixed with at least one component of said coating composition and - subsequently said pre-mixture is applied to a single surface or at least two surfaces of a substrate. In this embodiment, the mixture comprising a plurality of electrically conductive nanoobjects is usually pre-mixed with component (A) or component (B) of the coating composition as defined herein, in a concentration suitable for the purpose. All further process steps are essentially similar to the process steps as described here above with respect to other embodiment(s). In particular, after applying the pre-mixture there is typically a subsequent step of curing or annealing the coating composition or pre-mixture to receive a finished coating, preferably clear coating.

In preferred embodiments of the method of making of the present invention, a first, electrically conductive, transparent layer comprising a plurality of electrically conductive nanoobjects is created on the substrate (see above for preferred steps of making such first layer in a method of the present invention), wherein said first layer is subsequently detached from the surface of the substrate. Herein, the first layer preferably is a film and/or the detaching comprises peeling off the first layer from the surface of the substrate. According to this embodiment, the substrate does not remain a part of the single or multiple layer composite, but rather serves as a template. Thus, said substrate may be rigid or flexible, transparent or non-transparent. Preferably, however, the substrate used in this preferred embodiment has properties which facilitate the detaching or peeling off the first layer. A preferred suitable property for this purpose is a high hydrophobicity, in particular a high hydrophobicity of the substrate's surface carrying the first layer. As is known in the art, a high hydrophobicity of a substrate's surface can either be a property of the substrate itself, or the substrate's surface can be hydrophobized, e.g. by applying a self-assembled monolayer ("SAM") of organic molecules on the substrate's surface. SAMs of organic molecules are molecular assemblies formed spontaneously on surfaces by adsorption and are organized into more or less large ordered domains. For the pur- poses of the present invention, a suitable substrate, e.g. Si or glass, can be wetted with a suitable reagent for applying a SAM to the substrate's surface. Suitable reagents for applying a SAM to the substrate's surface are e.g. octadecyltrichlorosilane or dodecyltri- chlorosilane. Thus, the surface of preferred substrates is hydrophobized, i.e. modified so as to provide an increased hydrophobicity in comparison with the unmodified surface. In preferred embodiments of the method of making a single or multiple layer composite according to the present invention, said coating composition and said mixture comprising a plurality of electrically conductive nanoobjects, without pre-mixing, are applied to at least two different surfaces of a substrate (preferably two surfaces on opposite sides of a flat substrate) in separate steps, wherein in one application step, said mixture comprising a plurality of electrically conductive nanoobjects is applied to at least one surface of the substrate and in a separate application step, said coating composition is applied to at least one other (i.e., different, preferably opposite) surface of the substrate (so as to prepare a "first layer").

Preferably, in this preferred embodiment, the first layer (i)) has a thickness of not more than 500 μιη, preferably a thickness in a range of from 20 to 150 μιη, perpendicular to an interface of the layer.

Preferably, the coating composition applied in the separate application step does not comprise any electrically conductive nanoobjects.

Generally, the application steps in such preferred embodiments can be carried out analogously to the application steps as described above for the preferred embodiment of said method of making a single or multiple layer composite according to the present invention, wherein said coating composition and said mixture comprising a plurality of electrically conductive nanoobjects, without pre-mixing, are applied to at least one surface of a substrate in separate steps, but according to the present embodiment of course with the proviso, that said coating composition and said mixture comprising a plurality of electrically conductive nanoobjects are not applied to the same surface of a substrate, but are applied to different surfaces of the same substrate. The application steps in this preferred embodiment can be carried out in either order, i.e. the mixture comprising a plurality of electrically conductive nanoobjects can first be applied to at least one surface of the substrate, followed by applying said coating composition to at least one other surface of the same substrate, or the coating composition can first be applied to at least one surface of the substrate, followed by applying the mixture comprising a plurality of electrically conductive nanoobjects to at least one other surface of the same substrate, or both steps can be conducted simultaneously. In a variant of this preferred embodiment, said coating composition in a separate application step can also be applied in addition or alternatively (a) onto said mixture on the surface of the substrate or (β) onto the plurality of electrically conductive nanoobjects on the surface of the sub- strate. Preferred is applying the mixture comprising a plurality of electrically conductive nanoobjects and the coating composition to opposite sides of a flat substrate, selected from the group consisting of foils, films, webs, panes and plates. Preferably, after apply- ing to the surface(s) of the substrate, the mixture comprising a plurality of electrically conductive nanoobjects or the coating composition are first processed for better adhesion before applying the coating composition or mixture comprising a plurality of electrically conductive nanoobjects, respectively, to the respective other surface(s) of the substrate, i.e. the coating composition may be cured or annealed as described above and the mixture comprising a plurality of electrically conductive nanoobjects may be dried as described above.

The present invention also relates to a use of a coating composition, where said coating composition comprises:

(a) at least one binder (A) having reactive groups, which is a hydroxyl-containing

compound (A),

(c) at least one catalyst (C) for the crosslinking of silane groups, which is a phosphoric acid compound, more particularly phosphoric acid or phosphonic acid, which is blocked with a bicyclic amine having a pKb > 3 and a boiling point > 100°C, preferably a phosphoric acid compound selected from the group consisting of substituted phosphoric monoesters and phosphoric diesters, which is blocked with a bicyclic amine having a pKb > 3 and a boiling point > 100°C, where one or more constituents (A) and/or (B) and/or at least one further constituent of the coating composition contain hydrolysable silane groups, or a cured reaction product thereof, for making a scratch-resistant, transparent and electrically conductive single or multiple layer composite.

Generally, all aspects of the present invention discussed herein in the context of the inventive single or multiple layer composite, the coated article and the method of making apply mutatis mutandis to the use according to the present invention, as defined here above and below, and vice versa.

Preferred is a use according to the present invention wherein the single or multiple layer composite comprises a plurality of electrically conductive nanoobjects in the single layer or at least one of the multiple layers.

Surprisingly it has been found that the coating composition as defined above, or cured reaction products thereof, effectively protect an electrically conductive, transparent layer comprising a plurality of electrically conductive nanoobjects in the single or multiple layer composite of the invention, from mechanical stress or damage, in particular from scratch- es, while the optical and electrical properties of said electrically conductive, transparent layer comprising a plurality of electrically conductive nanoobjects are only partially, preferably not significantly, more preferably not at all affected or compromised. It has further been found that preferred embodiments of the present invention provide flexible, transparent, electrically conductive single or multiple layer composites with high scratch- resistance under mechanical stress (e.g. bending, scratching, wiping) and excellent optical and electrical properties.

This finding is particularly surprising for the single or multiple layer composites of the invention wherein the first layer and the electrically conductive, transparent layer are the same, and wherein the concentration of electrically conductive nanoobjects in the first layer has a gradient in a direction perpendicular to an interface of the layer.

Thus, a single or multiple layer composite of the invention preferably has one or more, more preferably it has all, of the following optical and/or electrical properties: a light transmission of 70 % or more, more preferred of 75 % or more, yet more preferred of 80 % or more, even more preferred of 85 % or more and yet even more preferred of 90 % or more, in each case in the visible region of the electromagnetic spectrum, i.e. in a range of from about 380 nm to 780 nm, more in particular in a range of from about 400 to 700 nm, when measured in each case according to standard method ASTM D 1003-13 (procedure A); a haze of 3 % or less, more preferred of 2 % or less, further preferably of 1.5 % or less, when measured in each case according to ASTM D1003-13 (procedure A); a sheet resistance in a range of from 10 to 150 ohm/sq, more preferably of from 10 to 60 ohm/sq, as measured by a non-contact-type sheet resistance measurement system (inductive measurement), preferably according to standard procedure ASTM F1844 - 97 (2016), on said surface of said first layer of said single or multiple layer composite.

The measurement of haze and light transmission by means of a hazemeter is defined in ASTM D1003-13 as "Procedure A - Hazemeter". The values of haze and light transmission (corresponding to the luminous transmittance as defined in ASTM D1003-13) given in the context of the present invention refer to this procedure. Generally, the parameter haze is an index of the light diffusion. It refers to the percentage of the quantity of light which is separated from the incident light and scattered during transmission. Unlike "light transmission", which is largely a property of the medium, "haze" is often a production concern and is typically caused by surface roughness, and by embedded particles or compositional heterogeneities in the medium. According to ASTM D1003-13, in light transmission, haze is the scattering of light by a specimen responsible for the reduction in contrast of objects viewed through said specimen, i.e. the percent of transmitted light that is scattered so that its direction deviates more than a specified angle (2.5 °) from the direction of the incident beam.

The sheet resistance (sometimes also referred to as "square resistance") is a measure of the resistance of a thin body (sheet), namely uniform in thickness. The term "sheet resistance" implies that the current flow is along the plane of the sheet, not perpendicular to it. For a sheet having a thickness t, a length L and a width W, the resistance R is given by the following equation:

R = p *— = ^ *— = R_sh *—

Wt t W W wherein R_sh is the sheet resistance. Accordingly the sheet resistance R_sh is given by the following equation:

In the equation given above, the bulk resistance R is multiplied with a dimensionless quantity (W/L) to obtain the sheet resistance Rsh, thus the unit of sheet resistance is "Ohm". For the sake of avoiding confusion with the bulk resistance R, the value of the sheet resistance is commonly indicated as "Ohms per Square" (ohm/sq.) because in the specific case of a square sheet, the following relationships apply: W = L and R = Rsh.

The sheet resistance can be measured by means of a "four point-probe" as is known in the art. Devices for use in four point probes and instructions for carrying out associated methods can be obtained, for example, from Four Point Probes / Bridge Technology, Chandler Heights AZ, 85127, USA. Preferably, the measuring of sheet resistances by the four point probe method can be carried out for the purposes of the present invention according to standard procedure ASTM F171 1 - 96 (2016).

The sheet resistance is however preferably measured by non-contact sheet resistance measurement, also known as inductive measurement. Generally, this method measures the shielding effect created by "eddy currents". Eddy currents (also called "Foucault currents") are loops of electrical current induced within conductors by a changing magnetic field in the conductor, due to Faraday's law of induction. Eddy currents flow in closed loops within conductors, in planes perpendicular to the magnetic field. They can be induced within nearby stationary conductors by a time-varying magnetic field created by an alternating current electromagnet or transformer, for example, or by relative motion be- tween a magnet and a nearby conductor. The magnitude of the current in a given loop is proportional to the strength of the magnetic field, the area of the loop, and the rate of change of flux, and inversely proportional to the resistivity of the material. Thereby a high- frequency magnetic field is generated and the sample is placed in the magnetic field. The conductive material acts on the resonant circuit, such as a resistive load and thus leads to a change in the power consumption in the oscillator circuit. In one version of this technique a conductive sheet under test is placed between two coils. This non-contact sheet resistance measurement method also allows characterizing encapsulated thin-films or films with rough surfaces. Suitable measuring systems are known and are commercially available, e.g. from Suragus GmbH, Dresden, Germany or from KITEC microelectronic technologie GmbH, Erding, Germany. Preferably, the measuring of sheet resistances by the non-contact sheet resistance measurement method is carried out for the purposes of the present invention according to standard procedure ASTM F1844 - 97 (2016).

The two methods for measuring sheet resistances provided herein (four point-probe and inductive measurement) are generally equivalent and sheet resistance values measured with any of the methods are usually essentially identical, within a measuring tolerance. The inductive measurement method is however preferred in cases where the electrically conductive medium (e.g. the electrically conductive nanoobjects and/or the electrically conductive transparent layer) are not directly accessible or cannot directly be contacted, e.g. because they are covered by an insulating medium. The inductive measurement method is therefore preferred for measuring sheet resistances of the single or multiple layer composites of the invention.

Examples:

The following examples are meant to further explain and illustrate the invention without limiting its scope.

If not otherwise stated, all experiments and/or measurements as provided herein were conducted under normal conditions (laboratory conditions: 20 °C, 1013 mbar, equivalent to 1013 hPa).

For measuring transmittance and haze according to ASTM D1003-13 (procedure A), an UV-Vis spectrometer "haze-gard I" (by BYK-Gardner Instruments) was used.

For measuring sheet resistances, a non-contact sheet resistance measurement system was used.

Cross-sectional specimens of layers, e.g. of single or multiple layer composites according to the invention, were prepared using a focused ion beam system (FIB, Helios Nanolab 450 F1 ).

For examining the surface and/or vertical morphology of specimens, e.g. of single or multiple layer composites according to the invention, a field-emission scanning electron microscope (FE-SEM, Philips XL30 ESEM-FEG) was used.

The appended figures schematically show the following:

Figure 1 : Shows an example of a single or multiple layer composite of the invention, where the first layer (1 ) and the electrically conductive, transparent layer comprising a plurality of electrically conductive nanoobjects (2) are the same (1 ,2) and the concentration of electrically conductive nanoobjects in the first layer has a gradient in a direction perpendicular to an interface of the layer. Figure 2: Shows an example of a single or multiple layer composite of the invention, where the first layer (1 ) and the electrically conductive, transparent layer comprising a plurality of electrically conductive nanoobjects (2) are the same (1 ,2) and the concentration of electrically conductive nanoobjects in the first layer is the same in all directions of the layer, i.e. the electrically conductive nanoobjects are homogeneously distributed within the first layer.

Figure 3: Shows an example of a single or multiple layer composite of the invention, where the first layer (1 ) and the electrically conductive, transparent layer comprising a plurality of electrically conductive nanoobjects (2) are different and are separated by one substrate layer (3).

Example 1 : Preparation of a single or multiple layer composite of the invention

A plurality of Ag nanowires which had a length in a range of from about 15 to 30 μιη (average length about 25 μιη) and a diameter in a range of from about 20 to 40 nm (average diameter about 30 nm) was deposited on a surface of a substrate made of glass, which had been pretreated with octadecyltnchlorosilane (by dipping the surface of the glass substrate into the octadecyltnchlorosilane, as is known in the art) by: forming on said surface of said substrate a wet film by applying by means of doctor- blade-coating a suspension of silver nanowires, dispersed in isopropyl alcohol as a carrier liquid, to said surface of said substrate and - removing said carrier liquid from the wet film formed on said surface of said substrate by evaporation (drying) for about 10 min. in air, at a temperature of about 120 °C, to produce an Ag nanowire network.

Subsequently, components "binder" ("Bindemittel") and "curative" ("Harter") of a coating composition - which was equivalent and/or comparable to a coating composition as disclosed in the "preparation examples" ("Herstellbeispiele") of patent EP 2225299 B1 (incorporated herein by reference), in particular a coating composition as shown in the "Formulation" ("Formulierung"), see table in paragraph [0092], composition of "product" ("Produkt") - were mixed with each other and applied to the dried Ag nanowire network using a doctor blade method, followed by curing or annealing the coating composition on the Ag nanowire network for about 20 min. at a temperature of about 140 °C in air. The thickness of the resulting clear coat could be steered by changing the blade height and/or the blade moving speed and/or it could be steered by the volume of coating composition that was fed into the doctor blade coating device. The resulting clear coat had a thickness of about 5 μιη, as determined by scanning electron microscopy (SEM).

The resulting overlay was finally peeled off the substrate by manually taping one edge of the overlay and pulling it off the substrate to yield an electrically conductive, flexible, transparent Ag nanowire electrode as a single layer composite according to the invention.

Example 2: Scratch test

Samples of Ag nanowire electrodes were prepared according to the method described in example 1. The samples were scratched manually (scratching force in a range of from about 1 to 5 N) on the surface of the composite layer where the coating composition had been applied, using a plastic pen. The total number of scratching was 100 times. Before the first scratching (n = 0) and then after every 20 scratches, values were recorded for (i) light transmission, (ii) haze and (iii) sheet resistance (for applicable methods see above) of the samples. The results of the scratch test are shown in table 1 below:Table 1 : Re- suits of scratch test

The results from example 2 show that, upon repeated scratching on the coated surface of the composite layer, its optical and electrical properties were not significantly impacted. Example 3: Bending test

Samples of Ag nanowire electrodes were prepared according to the method described in example 1. The samples were bent using a bending system, where two ends of a sample where anchored on opposite plates which were installed so as to be able to move towards and away from each other, thereby applying bending strain to a sample. The bending radius was 3 mm and the number of bending cycles was 100. Before the first bending (n = 0) and then after every 20 bendings, values were recorded for (i) light transmission, (ii) haze and (iii) sheet resistance of the samples (for applicable methods see above). The results of the bending test are shown in table 2 below:

Table 2: Results of bending test

The results from example 3 show that, upon repeated bending of the composite layer, its optical and electrical properties were not significantly impacted.

Example 4: Wiping test Samples of Ag nanowire electrodes were prepared according to the method described in example 1. A wiping test was performed on the samples using textiles soaked in isopropyl alcohol on the surface of the composite layer where the coating composition had been applied. Before the first wiping (n = 0) and then after every 5 wipings, values were recorded for (i) light transmission, (ii) haze and (iii) sheet resistance of the samples (for applicable methods see above). The results of the wiping test are shown in table 3 below: Table 3: Results of wiping test

The results from example 4 show that, upon repeated wiping on the coated surface of the composite layer, its optical and electrical properties were not significantly impacted.

Example 5: Impact of scratching on optical properties

Two samples of a common PET substrate (film type, thickness about 125 μιη) were provided, of which one was coated with a coating composition analogously as described in example 1 (thickness of coating about 5 μιη).

Both samples were then scratched manually, using a plastic pen, under comparable conditions (scratching force was about 1 to 5 N in each case). The samples were then examined for (i) visible scratches (using an optical microscope), (ii) light transmission properties before and after scratching (see above for method of determining light transmission) and (iii) haze properties before and after scratching (see above for method of determining haze).

As results of these tests, the following was found:

After the scratching test, the uncoated PET substrate clearly showed multiple scratches while the PET substrate coated with a coating composition as defined above hardly showed any scratches. After the scratching test, the uncoated PET substrate showed a significant decrease in light transmittance (from about 92 % to about 90 %), while the PET substrate coated with a coating composition as defined above only showed a very weak decrease in light transmittance. After the scratching test, the uncoated PET substrate showed a significant increase in haze (from about 0.75 % to about 2.0 %), while the PET substrate coated with a coating composition as defined above only showed a very weak increase in haze.

The results from example 5 show that the coating compositions as used in the present invention can effectively protect a flexible, transparent surface, e.g. a transparent sub- strate or an electrically conductive transparent layer comprising a plurality of electrically conductive nanoobjects, from mechanical damage, in particular from scratches, while effectively preserving the optical properties of the transparent surface.

Example 6: PLED lighting test

A flexible Ag nanowire electrode was prepared according to the method as provided in example 1 and applied as anode in an organic light emitting diode ("OLED"):

1 , 4, 5, 8, 9, 1 1 -hexaazatriphenylenehexacarbonitrile (HAT-CN), N,N'-Bis(naphthalen-1- yl)-N,N'-bis(phenyl)benzidine (NPB), tris(8-hydroxyguinoline)aluminum (Alg3), 8-hydroxy- guinolinolatolithium (Lig), Al, and Mo0₃ layers were seguentially deposited on the prepared flexible Ag nanowire electrode using a thermal evaporator (a base pressure of around 10^"6 Torr, eguivalent to about 1 ,33 x 10^~4 Pa) without an air exposure; thickness of each layer was about 35 nm (HAT-CN), 40 nm (NPB), 50 nm (Alg3), 1.5 nm (Lig), 100 nm (Al), and 50 nm (Mo0₃), respectively. In this OLED structure, HAT-CN, a-NPB, Alg3, Lig, and, Al worked as hole injection layer, hole transporting layer, emitting layer, electron injection layer, and cathode, respectively. Mo0₃ was used as a capping layer to prevent the oxidation of Al cathode.

The OLED so received was bent in different directions and the brightness of the OLED lighting visually inspected during and after bending.

It was found that the OLED lighting showed no noticeable degradation in brightness during or after bending.

Claims

Claims:

1. Single or multiple layer composite, comprising i) a first layer comprising a coating composition comprising (a) at least one binder (A) having reactive groups, which is a hydroxyl- containing compound (A),

(b) at least one crosslinking agent (B) which is able to react, with crosslinking with the reactive groups of the binder (A), which is a compound (B) having free and/or blocked isocyanate groups and (c) at least one catalyst (C) for the crosslinking of silane groups, which is a phosphoric acid compound, more particularly phosphoric acid or phosphonic acid, which is blocked with a bicyclic amine having a pKb > 3 and a boiling point > 100°C, where one or more constituents (A) and/or (B) and/or at least one further constituent of the coating composition contain hydrolysable silane groups, or a cured reaction product thereof, and ii) an electrically conductive, transparent layer comprising a plurality of elec- trically conductive nanoobjects, wherein said first layer and said electrically conductive, transparent layer are the same or different.

2. Single or multiple layer composite according to claim 1 , wherein catalyst (C) is selected from the group consisting of substituted phosphoric monoesters and phosphoric diesters, preferably from the group consisting of acyclic phosphoric diesters and cyclic phosphoric diesters.

Single or multiple layer composite according to any of the preceding claims, wherein one or more constituents of the coating composition at least partly contain one or more, identical or different structural units of the formula (I)

-X-Si-R"_XG₃-_X (I) with

G is/are identical or different hydrolysable groups, more particularly G is an alkoxy group (O R'),

X is an organic radical, more particularly linear and/or branched alkylene or cycloalkylene radical having a total number of 1 to 20 carbon atoms, very preferably X is an alkylene radical having a total number of 1 to 4 carbon atoms,

Single or multiple layer composite according to any of the preceding claims, wherein the electrically conductive nanoobjects are metal nanoobjects, wherein the metal is preferably selected from the group consisting of cobalt, copper, gold, iron, molybdenum, nickel, palladium, silver, tin, tungsten and alloys made of two or more of said metals.

Single or multiple layer composite according to any of the preceding claims, wherein component (c) of the coating composition comprises at least one catalyst (C) for the crosslinking of silane groups which is a phosphoric acid compound, selected from the group consisting of substituted phosphoric monoesters and phosphoric diesters, preferably from the group consisting of acyclic phosphoric diesters and cyclic phosphoric diesters, which is blocked with a bicyclic amine having a pKb > 3 and a boiling point > 100°C, and the electrically conductive nanoobjects are metal nanoobjects, wherein the metal is preferably selected from the group consisting of cobalt, copper, gold, iron, molybdenum, nickel, palladium, silver, tin, tungsten and alloys made of two or more of said metals

6. Single or multiple layer composite according to any of the preceding claims, wherein the first layer is transparent and clear, preferably the first layer is in the form of a transparent clear coating and/or wherein the single or multiple layer composite is flexible.

7. Single or multiple layer composite according to any of the preceding claims, further comprising one or more substrate layers.

8. Single or multiple layer composite according to any of the preceding claims, wherein said first layer and said electrically conductive, transparent layer are the same, and wherein the concentration of electrically conductive nanoobjects in the first layer has a gradient in a direction perpendicular to an interface of the layer or the concentration of electrically conductive nanoobjects in the first layer is the same in all directions of the layer. Single or multiple layer composite according to any of the preceding claims, wherein the first layer has a thickness of not more than 30 μιη, preferably a thickness in the range of from 0.1 to 30 μιη, perpendicular to an interface of the layer.

Single or multiple layer composite according to claims 1 to 7, wherein said first layer and said electrically conductive, transparent layer are different and wherein said first layer and said electrically conductive, transparent layer are separated from each other by one or more substrate layers.

Coated article, comprising a base article, and a coating on the base article, wherein the coating is a single or multiple layer composite according to any of claims 1 to 10.

Method of making a single or multiple layer composite according to any of claims 1 to 10 or a coated article according to claim 1 1 , comprising the following steps: providing or preparing a coating composition, said coating composition comprising

(b) at least one crosslinking agent (B) which is able to react, with cross- linking with the reactive groups of the binder (A), which is a compound (B) having free and/or blocked isocyanate groups and

(c) at least one catalyst (C) for the crosslinking of silane groups, which is a phosphoric acid compound, more particularly phosphoric acid or phosphonic acid, which is blocked with a bicyclic amine having a pKb > 3 and a boiling point > 100°C, preferably a phosphoric acid compound selected from the group consisting of substituted phosphoric monoesters and phosphoric diesters, which is blocked with a bicyclic amine having a pKb > 3 and a boiling point > 100°C, where one or more constituents (A) and/or (B) and/or at least one further constituent of the coating composition contain hydrolysable silane groups, providing or preparing a mixture comprising a plurality of electrically conductive nanoobjects,

applying said coating composition and said mixture to a single surface or at least two different surfaces of a substrate, o in a single step after pre-mixing of said coating composition with said mixture

o in separate steps without pre-mixing of said coating composition with said mixture.

Method according to claim 12, wherein said coating composition and said mixture comprising a plurality of electrically conductive nanoobjects, without pre-mixing, are applied to at least one surface of a substrate in separate steps, wherein in a first application step said mixture comprising a plurality of electrically conductive nanoobjects is applied to the surface of the substrate and subsequently in a second application step said coating composition is applied o onto the mixture on the surface of the substrate or o onto the plurality of electrically conductive nanoobjects on the surface of the substrate, so that a first, electrically conductive, transparent layer comprising a plurality of electrically conductive nanoobjects is created on the substrate, wherein preferably

Method according to claim 13, wherein said first layer is subsequently detached from the surface of the substrate, wherein the first layer preferably is a film and/or the detaching comprises peeling off the first layer from the surface of the substrate.

Use of a coating composition, said coating composition comprising

Use according to claim 15, wherein the single or multiple layer composite comprises a plurality of electrically conductive nanoobjects in the single layer or at least one of the multiple layers.