The process of creating thin films on a substrate, materials including thin films, and preparations including polysiloxane.

Abstract

The invention relates to a process for producing thin films on a substrate from a composition of polysiloxane containing silane monomers of formulations (I) and (II) as defined below, an article, preferably an article with a coated metal surface or an anodized aluminum, including the thin films that can be obtained by this process; the composition of which consists of polysiloxane containing at least two silane monomers of formulations (I) and (II) and describes the use of such composition for producing coatings on the article.

Description

[0001] Easy to clean coatings with low fingerprint visibility

[0002] The present invention relates to a process for preparing a thin film on a substrate from a composition comprising a polysiloxane comprising silane monomers according to formulas (I) and (II) as defined below, an article, preferably an article with a coated metal or anodized aluminum surface, comprising the thin film obtainable by said process; a composition comprising said polysiloxane comprising at least two silane monomers according to formulas (I) and (II) and the use of said composition for preparing a coating on an article.

[0003] Technical background

[0004] For many applications, such as touch panel displays, tablet and laptop computer and mobile phone enclosures and covers, console panels, home appliances, kitchen and other worktop surfaces, solar panel screens, and windows it is important to be able to keep the surface clear from stains for hygienic and visual appearance reasons as well as to be able to use the device with its best potential.

[0005] Human beings naturally produce sebum and other oily substances from face and fingertips, which are deposited on surfaces, such as ceramics, glass, metals, natural and man-made stone, polymeric materials of any kind of articles, such as display screens and device enclosures and covers. On surfaces, such as the above mentioned applications, the oily substances are often visible and can reduce the aesthetic quality or even reduce the technical quality of the surface, e.g. by reducing the quality of images seen on a display.

[0006] Invisible fingerprint (IFP) coatings are generally oleophilic coatings, which cause the oily substances e.g. from fingerprints, to spread along the surface so that they do not reflect light and appear transparent and therefore are invisible or nearly invisible. In contrast to that on more hydrophilic coatings having a rather high oil contact angle (OCA) oily substances form microdroplets, which reflect light and make fingerprints appear white. Especially on dark surfaces, such as displays, transparent fingerprints appearing black instead of white are preferable, as black appearing fingerprints contribute better to the invisibility compared to white fingerprints.

[0007] An invisible fingerprint coating should have sufficient hydrophobicity, e.g. indicated in water contact angles (WCA) and oil contact angles (OCA) to cause the oily substances e.g. from fingerprints, to spread along the surface, and to be easy to clean (E2C).

[0008] Additionally, an invisible fingerprint coating should have good abrasion and wear resistance and stabile performance against common chemicals, which may get in contact with the coating. Furthermore, the coating should have sufficient thermal, UV stability and stability against changing ambient condition such as high humidity combined with high temperature. Finally the coating has to be applicable by standard industrial coating techniques.

[0009] The present invention resides in the finding of a polysiloxane coating on surfaces, based on a specific selection of silane monomers, which surprisingly show good IFP properties, in which fingerprints are transparent and appear black on dark surfaces resulting in very low visibility, represent good easy cleanability (E2C) properties and high abrasion and chemical resistances. Furthermore, the polysiloxane coating is applicable as single layer coating on article surfaces. Finally the present invention provides a process for producing a fluoro-free thin film on article surfaces.

[0010] Summary of the invention

[0011] In a first aspect the present invention relates to a process for preparing a thin film on a substrate, the process comprising the steps of a) admixing at least two different silane monomers to a first solvent to form a mixture, with the proviso that

[0012] • a first silane monomer is selected from compounds of formula (I)

[0013] Si(O-R1)4(I) wherein

[0014] R1is independently selected from a linear or branched alkyl group having 1 to 10, preferably 1 to 6, more preferably 1 or 2 carbon atoms; and

[0015] • a second silane monomer is selected from compounds of formula (II)

[0016] Ar-Si(R2)a(O-R3)3-a(II) wherein

[0017] Ar is a substituted or unsubstituted aromatic group, preferably selected from a substituted or unsubstituted phenyl group, naphthyl group, anthracenyl group and phenanthrenyl group, more preferably an unsubstituted phenyl group; R2is independently selected from hydrogen and a linear or branched hydrocarbyl group, preferably a linear or branched alkyl group having 1 to 10, more preferably 1 to 6, still more preferably 1 or 2 carbon atoms;

[0018] R3is independently selected from a linear or branched alkyl group having 1 to 10, preferably 1 to 6, more preferably 1 or 2 carbon atoms; and a is 0 or 1 , preferably 1 ; b) at least partially hydrolysing the silane monomers in the presence of a catalyst and polymerizing at least the silane monomers according to formulas (I) and (II) to obtain a composition comprising a polysiloxane comprising silane monomers according to formulas (I) and (II); c) optionally changing the first solvent to a second solvent; d) forming a thin layer from the composition obtained in step c), if present, or step b) on the substrate; e) optionally partially or completely removing solvent, if present, after step d); f) curing the intermediate product obtained in step e), if present, or step d), if step e) is not present, thereby obtaining a thin film.

[0019] In a further aspect the present invention relates to an article, preferably an article with a coated metal or anodized aluminum surface, comprising the thin film obtainable by the process as defined above or below as a coating on at least one surface, preferably a coated metal or anodized aluminum surface of said article.

[0020] In yet another aspect the present invention relates to a composition comprising a polysiloxane comprising at least two silane monomers according to formulas (I) and (II)

[0021] Si(O-R1)4(I) wherein

[0022] R1is independently selected from a linear or branched alkyl group having 1 to 10, preferably 1 to 6, more preferably 1 or 2 carbon atoms; and

[0023] Ar-Si(R2)a(O-R3)3-a(II) wherein

[0024] Ar is a substituted or unsubstituted aromatic group, preferably selected from a substituted or unsubstituted phenyl group, naphthyl group, anthracenyl group and phenanthrenyl group, more preferably an unsubstituted phenyl group;

[0025] R2is independently selected from hydrogen and a linear or branched hydrocarbyl group, preferably a linear or branched alkyl group having 1 to 10, more preferably 1 to 6, still more preferably 1 or 2 carbon atoms;

[0026] R3is independently selected from a linear or branched alkyl group having 1 to 10, preferably 1 to 6, more preferably 1 or 2 carbon atoms; and a is 0 or 1 , preferably 1 . In still another aspect the present invention relates to the use of the composition as described above or below for preparing a coating on an article, preferably an invisible fingerprint coating on an article.

[0027] The thus obtained coatings provide good IFP properties, in which fingerprints appear in black, high abrasion resistance and excellent surface cleanability.

[0028] Detailed description of the invention

[0029] In a first aspect the present invention relates to a process for preparing a thin film on a substrate, the process comprising the steps of a) admixing at least two different silane monomers to a first solvent to form a mixture, with the proviso that

[0030] • a first silane monomer is selected from compounds of formula (I)

[0031] Si(O-R1)4(I) wherein

[0032] R1is independently selected from a linear or branched alkyl group having 1 to 10, preferably 1 to 6, more preferably 1 or 2 carbon atoms; and

[0033] • a second silane monomer is selected from compounds of formula (II)

[0034] Ar-Si(R2)a(O-R3)3-a(II) wherein

[0035] Ar is a substituted or unsubstituted aromatic group, preferably selected from a substituted or unsubstituted phenyl group, naphthyl group, anthracenyl group and phenanthrenyl group, more preferably an unsubstituted phenyl group;

[0036] R2is independently selected from hydrogen and a linear or branched hydrocarbyl group, preferably a linear or branched alkyl group having 1 to 10, more preferably 1 to 6, still more preferably 1 or 2 carbon atoms;

[0037] R3is independently selected from a linear or branched alkyl group having 1 to 10, preferably 1 to 6, more preferably 1 or 2 carbon atoms; and a is 0 or 1 , preferably 1 ; b) at least partially hydrolysing the silane monomers in the presence of a catalyst and polymerizing at least the silane monomers according to formulas (I) and (II) to obtain a composition comprising a polysiloxane comprising silane monomers according to formulas (I) and (II); c) optionally changing the first solvent to a second solvent; d) forming a thin layer from the composition obtained in step c), if present, or step b) on the substrate; e) optionally partially or completely removing solvent, if present, after step d); f) curing the intermediate product obtained in step e), if present, or step d), if step e) is not present, thereby obtaining a thin film.

[0038] “Different” in this connection means that the silane monomers differ in at least one chemical moiety.

[0039] The first silane monomer is selected from compounds of formula (I) Si(O-R1)4(I) wherein

[0040] R1is independently selected from a linear or branched alkyl group having 1 to 10, preferably 1 to 6, more preferably 1 or 2 carbon atoms.

[0041] The first silane monomer according to formula (I) is a tetraalkyloxysilane. Thereby, the alkyl-groups of residue R1can be the same or different.

[0042] The first silane monomer is preferably selected from tetramethoxysilane and tetraethoxysilane and mixtures thereof. Especially preferred is tetraethoxysilane.

[0043] The second silane monomer is selected from compounds of formula (II) Ar-Si(R2)a(O-R3)3-a(II) wherein

[0044] Ar is a substituted or unsubstituted aromatic group, preferably selected from a substituted or unsubstituted phenyl group, naphthyl group, anthracenyl group and phenanthrenyl group, more preferably an unsubstituted phenyl group;

[0045] R2is independently selected from independently selected from hydrogen and a linear or branched hydrocarbyl group, preferably a linear or branched alkyl group having 1 to 10, more preferably 1 to 6, still more preferably 1 or 2 carbon atoms;

[0046] R3is independently selected from a linear or branched alkyl group having 1 to 10, preferably 1 to 6, more preferably 1 or 2 carbon atoms; and a is 0 or 1 , preferably 1 . The optional substituents of the aromatic group Ar are preferably selected from Ci to C20 organyl or organoheteryl groups.

[0047] The heteroatom(s) present in the organoheteryl group of R2are preferably selected from N, O, P or S, more preferably selected from N and O.

[0048] An organyl group is an organic substituent group, having one free valence at a carbon atom.

[0049] An organoheteryl group is an organic substituent group, having one free valence at an atom different from a carbon atom.

[0050] The second silane monomer is selected from phenylmethyldimethoxysilane, phenylmethyldiethoxysilane, phenylethyldimethoxysilane, phenylethyldiethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane and mixtures thereof, preferably phenylmethyldimethoxysilane, phenylmethyldiethoxysilane, phenylethyldimethoxysilane, phenylethyldiethoxysilane and mixtures thereof.

[0051] Especially preferred are phenylmethyldimethoxysilane, phenylmethyldiethoxysilane and mixtures thereof. Most preferred is phenylmethyldimethoxysilane.

[0052] In step a) one or more, such as one to five, preferably one to three, more preferably one or two, still more preferably one silane monomer is selected from compounds of formula (I) and one or more, such as one to five, preferably one to three, more preferably one or two, still more preferably one silane monomer is selected from compounds of formula (II) are used to form the mixture.

[0053] Additionally, silane monomers different from the first and second silane monomers can be added to the mixture.

[0054] In one embodiment the at least two different silane monomers consist of one silane monomer according to formula (I) and one silane monomer according to formula (II).

[0055] In said embodiment, the first silane monomer is preferably selected from tetramethoxysilane and tetraethoxysilane and mixtures thereof, more preferably is tetraethoxysilane, and the second silane monomer is preferably selected from phenylmethyldimethoxysilane, phenylmethyldiethoxysilane and mixtures thereof, more preferably is phenylmethyldimethoxysilane.

[0056] In another embodiment, in step a) additionally one or more, such as one to five, preferably one to three, more preferably one or two, still more preferably one silane monomers different from the first and second silane monomer of formulas (I) and (II) are preferably admixed together with the first and second silane monomer of formulas (I) and (II) to the first solvent.

[0057] The one or more silane monomers different from the first and second silane monomer of formulas (I) and (II) are preferably selected from (3-glycidyloxypropyl)trimethoxysilane (GPTMS), (3-glycidoxypropyl)triethoxysilane (GPTEOS), methyl triethoxysilane (MTEOS), n-octyl trimethoxysilane (n-octylTMS), n-propyl triethoxysilane (n- propylTEOS), n-hexyl triethoxysilane (n-hexylTEOS), dodecyl triethoxysilane (dodecylTEOS), 3-[Bis(2-hydroxyethyl)amino]propyl triethoxysilane (BHEAPTEOS), methyltrimethoxysilane (MTMS), dimethyldiethoxysilane (DMDEOS), 3- trimethoxysilylpropyl methacrylate (MEMO), Bis(triethoxysilyl)ethane) (BTESE), Bis(methyldiethoxysilyl)ethane (BMDESE), 1 H, 1 H, 2H, 2H- perfluorooctyltrimethoxysilane (F13), 1 H, 1 H, 2H, 2H-perfluorodecyltrimethoxysilane (F17), 11 -chloroundecyltriethoxysilane (CI(CH2)nTEOS); 2-(3.4-Epoxycyclohexyl)ethyl triethoxysilane (ECHETEOS), hydroxymethyl triethoxysilane (HMTEOS), N-(3- triethoxysilylpropyl)gluconamide (NGPTEOS), (phenanthrene-9-yl) triethoxysilane ((phenanthrene-9-yl)TEOS), n-octyltrimethoxysilane (n-octylTMS), n- hexyltrimethoxysilane (n-hexylTMS), octaethoxy-1 ,3,5-trisilapentane (OEOSTSP), aminopropyltriethoxysilane (APTEOS), aminopropyltrimethoxysilane (APTMSdiphenyldimethoxysilane (DPDMS), diphenyldiethoxysilane (DPDEOS), dimethyldimethoxysilane (DMDMS), dimethyldiethoxysilane (DMDEOS), (3- glycidoxypropyl)methyldimethoxysilane (MGPDMS), (3- glycidoxypropyl)methyldiethoxysilane (MGPDEOS), 1 ,4-Bis(triethoxysilyl)benzene (BTESB), 1 ,4-Bis(trimethoxysilyl)benzene (BTMSB), hexadecyltrimethoxysilane (HDCTMS) and mixtures thereof. It is preferred that the one or more silane monomers different from the first and second silane monomer of formulas (I) and (II) comprise (3-glycidyloxypropyl)trimethoxysilane (GPTMS), (3-glycidoxypropyl)triethoxysilane (GPTEOS) and mixtures thereof.

[0058] It is especially preferred that the one or more silane monomers different from the first and second silane monomer of formulas (I) and (II) are selected from (3- glycidyloxypropyl)trimethoxysilane (GPTMS), (3-glycidoxypropyl)triethoxysilane (GPTEOS) and mixtures thereof, most preferably is (3- glycidyloxypropyl)trimethoxysilane (GPTMS).

[0059] In said embodiment the first silane monomer is preferably selected from tetramethoxysilane and tetraethoxysilane and mixtures thereof, more preferably is tetraethoxysilane, the second silane monomer is preferably selected from phenylmethyldimethoxysilane, phenylmethyldiethoxysilane and mixtures thereof, more preferably is phenylmethyldimethoxysilane, and the one or more silane monomers different from the first and second silane monomer of formulas (I) and (II) are selected from (3-glycidyloxypropyl)trimethoxysilane (GPTMS), (3-glycidoxypropyl)triethoxysilane (GPTEOS) and mixtures thereof, most preferably is (3-glycidyloxypropyl)trimethoxysilane (GPTMS).

[0060] In one specific embodiment it is preferred that in step a) tetraethoxysilane, phenylmethyldimethoxysilane and optionally (3-glycidyloxypropyl)trimethoxysilane are admixed to a first solvent to form a mixture.

[0061] In one embodiment the sum of silane monomers comprise a fluorine containing silane monomer. In said embodiment the polysiloxane comprises fluorine containing units.

[0062] In a second, preferred, embodiment the sum of silane monomers is free of fluorine containing silane monomers. In said embodiment, the polysiloxane is free of fluorine containing units. The molar ratio of the first silane monomer to the second silane monomer is preferably in the range of from 5.0 : 1 .0 to 1 .0 : 2.5, more preferably from 4.0 : 1 .0 to 1 .0 : 1 .0, still more preferably from 3.5 : 1.0 to 1.5 to 1.0, most preferably from 3.0: 1.0 to 2.0 : 1.0.

[0063] The molar ratio of the one or more silane monomers different from the first and second silane monomer of formulas (I) and (II), if present, to the combined molar amount of the first and second silane monomer is preferably in the range of from 1 .0 : 5.0 to 1 .0 : 30.0, more preferably from 1 .0 : 7.5 to 1 .0 : 25.0, most preferably from 1 .0 : 8.5 to 1 .0 to 20.0.

[0064] The first solvent is preferably selected from the group of ethanol (EtOH), acetone, 2- propanol (IPA), 1-propanol, propylene glycol methyl ether acetate (PGMEA), 1-methoxy- 2-propanol (PGME), tetrahydrofuran (THF), and mixtures thereof.

[0065] The at least two different silane monomers can be admixed in the first solvent at any suitable temperature for solving the silane monomers. Usually, room temperature suffices.

[0066] In the next method step the mixture is subjected to an at least partial hydrolysis in the presence of a catalyst.

[0067] Suitable catalysts are acidic catalysts, basic catalysts, or other catalysts.

[0068] Acidic catalysts are preferably selected from nitric acid (HNO3), sulfuric acid (H2SO4), formic acid (HCOOH), hydrochloric acid (HCI), sulfonic acid, hydrogen fluoride (HF), acetic acid (CH3COOH), trifluoromethanesulfonic acid or p-toluene sulfonic acid. Especially preferred acidic catalysts are nitric acid (HNO3) hydrochloric acid (HCI) and formic acid (HCOOH).

[0069] Basic catalysts are preferably selected from potassium hydroxide (KOH), sodium hydroxide (NaOH), triethylamine (TEA), ammonium hydroxide (NH4OH), tetraethylammonium hydroxide (TEAH), tetramethylammonium hydroxide (TMEA), 1 ,4- diazabicyclo[2.2.2]octane, imidazole and diethylenetriamine.

[0070] Other catalysts are preferably selected from 2,2,3,3,4,4,5,5-octafluoropentylacrylate, polyethylene glycol) 200, polyethylene glycol) 300 and n-butylated melamine formaldehyde resin. The hydrolysis step is preferably performed at a temperature of from 20 to 80°C for 1 to 24 hours, such as at room temperature overnight.

[0071] During the hydrolysis step the silane monomers are at least partially hydrolysed. Said at least partially hydrolysed silane monomers then are at least partially polymerized, preferably by condensation polymerization and crosslinked to form a siloxane polymer. Said polysiloxane usually has a relatively low molecular weight in range of about 500 to 5000 g / mol.

[0072] According to a preferable embodiment the subjecting the mixture to an at least partial hydrolysis includes refluxing. A typical refluxing time is 2 h.

[0073] The first solvent can be changed to a second solvent in an optional further method step after the hydrolysis step. The optional solvent change is advantageous, since it assists the removal of water and alcohols formed during hydrolysis of the silane monomers. In addition, it improves the properties of the final siloxane polymer solution when used as thin film, e.g. as coating, on the substrate.

[0074] The second solvent is preferably selected from the group of 1-methoxy-2-propanol (PGME), methyl ethyl ketone (MEK), 2-propanol (IPA), Dipropylene glycol n-butyl ether (DPnB), Diethylene glycol mono-n-hexyl ether (DEnH), Diethylene glycol monobutyl ether (DEG monobutyl ether or DEGBE or DEnB), Diethylene glycol monoethyl ether (DEGEE), Dipropylene glycol (DiPG), toluene, propylene glycol methyl ether acetate (PGMEA), ethylene glycol (EG), 1 -butanol, 2-butanol, tert-butanol, / so-butanol, propylene glycol butyl ether (PnB), mixture of the two inseparable regioisomers of methoxy-nonafluorobutane (Novec 7100), mixture of the two inseparable regioisomers of ethoxy-nonfluorobutane (Novec 7200), 1 ,1 ,1 ,2,2,3,4,5,5,5-decafluoro-3-methoxy-4- (trifluoromethyl)pentane(Novec 7300), and mixtures thereof.

[0075] Novec 7100, Novec 7200 and Novec 7300 are commercially available from 3M.

[0076] In one embodiment, the second solvent is free of fluorine-containing solvents.

[0077] In said embodiment, the composition including polysiloxane and solvent is preferably free of fluorine containing units.

[0078] It is preferred that in said embodiment the thin film is a fluoro-free invisible fingerprint coating. In a second embodiment, the second solvent comprises a fluorine-containing solvent. It is e.g. possible to introduce additives

[0079] The mixture comprising the siloxane polymer can be further subjected to a crosslinking step after the hydrolysis step. Thereby, the siloxane polymer is preferably at least partially crosslinked by thermal or radiation initiation.

[0080] In the present context, the term “partially crosslinked” means that the polymer is capable of further crosslinking at conditions conducive to cross-linking. In practice, the polymer still contains at least some reactive, crosslinking groups after the first polymerisation step. The further crosslinking, which typically takes place after deposition of the partially crosslinked composition on a substrate, will be described below.

[0081] The siloxane polymer is preferably at least partially crosslinked by thermal or radiation initiation using catalysts as described above.

[0082] Thereby, thermal crosslinking is preferably conducted at temperatures in the range of about 30 to 200 °C.

[0083] Typically cross-linking is carried out at refluxing conditions of the solvent.

[0084] The siloxane polymer can be optionally partially cross-linked during polymerization, in particular during or immediately after condensation polymerization. Various methods can be used for achieving cross-linking. For example, cross-linking method where two chains are joined via reactive groups can be employed. One example is cross-linking through double bonds or epoxy groups.

[0085] As a result of the partial cross-linking, the molecular weight will typically be 2- to 10- folded. Thus from a molecular weight in the range of about 500 to 5000 g / mol, the crosslinking will increase it above 3000, preferably to 4000 to 20000 g / mol.

[0086] The molecular weight of the polymer can be also increased by performing an additional polycondensation step. The remaining free alkoxy groups, which have not been hydrolysed, can further react with each other. This step is generally performed using a base catalyst, preferably nitrogen-containing bases such as imidazole or tri(alkyl)amine. Optionally, resulting free Si-OH groups present in backbone of the siloxane polymer can be protected by an end-capping. For end capping, the free Si-OH groups are reacted with silanes such as methyldichlorofluorosilane (ChFSiCHs, methylfluorodimethoxysilane ((MeO^SiFCHs), 3-chloropropyltrimethoxysilane (CI(CH2)3Si(OMe)3), trimethyltriethoxysilane (EtOTMS), trimethylchlorosilane, (CISiMes), or trimethylmethoxysilane (MeOTMS) in presence of a catalyst such as triethylamine (TEA) or imidazole. The amount of catalyst varies from 1 .5 to 2 wt% of total solid. The reaction time varies from 5 to 45 min at RT or elevated temperature in the range of from 40 to 125°C, preferably 80 to 110°C (for example 105 °C).

[0087] Other additives typically introduced into the composition comprising a siloxane polymer include chemicals that can further modify the final surface properties of coated and cured film or improve wettability / adhesion properties of the coating layer to the substrate or improve coating drying and packing behavior during deposition and drying to reach good visual quality.

[0088] These additives can be surfactants, defoamers, antifouling agents, wetting agents etc. Examples of such additives include: BYK-301 , BYK-306, BYK-307, BYK-308, BYK-333, BYK-051 , BYK-036, BYK-028, BYK-057A, BYK-011 , BYK-055, BYK-036, BYK-067A, BYK-088, BYK-302, BYK-310, BYK-322, BYK-323, BYK-33I, BYK-333, BYK-341 , BYK- 345, BYK-348, BYK-370, BYK-377, BYK-378, BYK-381 , BYK-390, BYK-3700, BYK- 3701 , all commercially available from BYK.

[0089] The additives are preferably present in an amount of 0.01-5 wt% by weight, more preferably 0.1 to 1 wt% of the total weight of the solids.

[0090] The additives can be added at any step of the method according to the invention. It is e.g. possible to introduce additives during admixing step a), optional solvent exchange step c) or in an additional step before forming the thin layer on the substrate in step d). Preferably the additives are added during the optional solvent exchange step c).

[0091] Before further condensation the excess of water is preferably removed from the material and at this stage it is possible to make a solvent exchange to another synthesis solvent if desired. This other synthesis solvent may function as the final or one of the final processing solvents of the siloxane polymer. The residual water and alcohols and other by-products may be removed after the further condensation step is finalized. Additional processing solvent(s) may be added during the formulation step to form the final processing solvent combination. Additives such as thermal initiators, radiation sensitive initiators, sensitizers, surfactants, and other additives may be added prior to final filtration of the siloxane polymer. After the formulation of the composition, the polymer is ready for processing in, for example, roll-to-roll film deposition or in a lithographic process.

[0092] After synthesis, the siloxane polymer composition can be diluted using a proper solvent or solvent combination to give a solid content which in film deposition will yield the preselected film thickness.

[0093] The composition as described above may comprise solid nanoparticles or other compounds in an amount of between 1 and 50 wt-% of the composition. The nanoparticles (or similar nano-, or microscale rods, crystals, spheres, dots, buds etc.) are in particular selected from the group of light scattering, light absorbing, light emitting and / or conductive pigments, dyes, organic and inorganic phosphors, oxides, quantum dots, polymers or metals.

[0094] In step d) a thin layer from the composition obtained in step c), if present, or step b) on the substrate is formed.

[0095] Suitable substrates include ceramics, glass, metals, natural and man-made stone, polymeric materials (such as poly(meth)acrylate, polycarbonate, polystyrene, styrene copolymers, such as styrene acrylonitrile copolymers, polyesters, polyethylene terephthalate), paints (such as those on acrylic resins), powder coatings (such as polyurethane or hybrid powder coatings), wood and fibrous substrates (such as textile, leather, carpet, paper). Preferably, the substrate is selected from ceramics, glass, metals, polymeric materials (such as poly(meth)acrylate, polycarbonate, polystyrene, styrene copolymers, such as styrene acrylonitrile copolymers, polyesters, polyethylene terephthalate), natural and man-made stone, more preferably from metals, ceramics, glass and polymeric materials (such as poly(meth)acrylate, polycarbonate, polystyrene, styrene copolymers, such as styrene acrylonitrile copolymers, polyesters, polyethylene terephthalate). The coating according to the present invention is especially suitable for dark colored substrates made of materials as described above, preferably for metal or anodized aluminum substrates, but not limited to these.

[0096] Step d) is preferably effected by dip coating, slot coating, combined slot+spin coating, spin coating, spray coating, ink-jet printing, curtain coating, roller coating, roll-to-roll coating, screen printing or using a bar, a brush or by rubbing, more preferably by spray coating, slot coating, dip coating, spin coating, most preferably spray coating and spin coating (to mention few typical liquid phase deposition methods but not limited to these). Such methods are known in the art.

[0097] The temperature during step d) preferably does not exceed 75°C, more preferably does not exceed 50°C and most preferably does not exceed 35°C.

[0098] The temperature of the substrate during step d) preferably does not exceed 100°C, more preferably does not exceed 50°C and most preferably does not exceed 35°C. In some cases, it might be preferable to make deposition on pre-heated substrate.

[0099] After forming the thin layer on the substrate in step d) and before curing the intermediate product in step f) a pattern can be formed into the thin film to form surface structures and patterns. Suitable methods for pattern forming are nano-imprinting, embossing, roll- to-roll, gravure, flexo-graphic, roller, ink-jet, screen-printing, spray and or UV lithography is used as patterning process) is used the form surface structures (nano-scale or micro or millimeter scale).

[0100] The purpose of the pattern forming is to produce additional optical, physical or chemical properties to the thin film.

[0101] In case solvent(s) are present in step d) in step e) the solvent(s) are preferably partially or completely removed. Step e) is optional and not typically necessary. There are differences between the deposition method and manufacturing line specifications.

[0102] In addition to temperature, also vacuum dry step can be optionally applied to promote the evaporation of the solvent(s). If vacuum dry step is used, typically it is applied first and followed by the thermal pre-cure. Usually, the removal is accomplished at a pressure of 50 to 200 kPa and / or followed by thermal cure at a temperature of 50 to 200 °C, preferably the removal is accomplished at a pressure of 90 to 115 kPa and / or followed by thermal cure at a temperature of 60 to 150 °C.

[0103] The optional thermal pre-cure is usually effected by exposure to heat, e.g. by using a convection oven, hot plate or IR irradiation.

[0104] The optional vacuum dry is carried out by specific equipment capable to remove solvents by applying high vacuum in specific chamber in which the coated substrate is loaded.

[0105] In step f) the intermediate product obtained in step e), if present, or step d), if step e) is not present, is cured.

[0106] The curing is usually effected by exposure to heat, e.g. by using a convection oven, hot plate or IR irradiation. Optionally also combined thermal and UV cure process can be used.

[0107] The temperature used for curing usually does not exceed 300°C preferably does not exceed 250°C and most preferably does not exceed 200°C or does not exceed 80°C.

[0108] The curing time is usually 10 min to 5.0 hours, preferably 20 min to 3.0 hours, and most preferably 5 min to 1 .0 hour.

[0109] The thickness of the thin film after step f) is preferably 15 to 300 nm, more preferably 30 to 250 nm.

[0110] The thin film on the substrate preferably serves as coating on at least one surface of an article, more preferably as invisible fingerprint coating on at least one surface of an article.

[0111] By carefully selecting the silane monomers and / or solvents to be fluorine-free a fluorine- free coating on at least one surface of an article, more preferably a fluorine-free invisible fingerprint coating on at least one surface of an article can be obtained. The film preferably has an initial water contact angle of at least 60°, preferably at least 63°, most preferably at least 67°.

[0112] The upper limit of the initial water contact angle is usually not more than 100°, preferably not more than 94°.

[0113] The film preferably has an initial oil contact angle of not more than 70°, preferably not more than 67°, most preferably not more than 65°.

[0114] The lower limit of the initial oil contact angle is usually at least 30°, preferably at least 35°.

[0115] The film preferably has a water contact angle after 200 cycles steel wool abrasion of at least 55°, more preferably at least 60° and most preferably at least 62°.

[0116] The upper limit of the water contact angle after 200 cycles steel wool abrasion is usually not more than 100°, preferably not more than 95°.

[0117] The film preferably has a water contact angle after 500 cycles steel wool abrasion of at least 55°, more preferably at least 57° and most preferably at least 60°.

[0118] The upper limit of the water contact angle after 500 cycles steel wool abrasion is usually not more than 95°, preferably not more than 90°.

[0119] The film further preferably shows good invisible fingerprint properties, easy to clean properties and chemical resistance.

[0120] Fingerprints on the thin film preferably do not reflect light and therefore appear as transparent fingerprints. When applied on dark surfaces the fingerprints on the thin film preferably appear as black.

[0121] Chemical resistance is determined as water contact angle and visual quality inspection after applying different chemical substances on the thin film.

[0122] The film preferably has a water contact angle after applying chemical substances of at least 45°, more preferably at least 47° and most preferably at least 50°.

[0123] The upper limit of the water contact angle after applying chemical substances is usually not more than 110°, preferably not more than 105°. Article

[0124] The present invention is furthermore directed to an article, preferably an article with a coated metal or anodized aluminum surface, comprising the thin film obtainable by the process according to the present invention.

[0125] The article may be a touch panel display, such as a handheld touch panel display or other interactive touch screen device, a tablet and laptop computer and mobile phone enclosure and cover, a console panel, a home appliance, a kitchen and other worktop surface, a solar panel screen, a window and an article with a metal surface.

[0126] Suitable materials for the articles which comprises the thin film obtainable by the process according to the invention include ceramics, glass, metals, natural and manmade stone, polymeric materials (such as poly(meth)acrylate, polycarbonate, polystyrene, styrene copolymers, such as styrene acrylonitrile copolymers, polyesters, polyethylene terephthalate), paints (such as those on acrylic resins), powder coatings (such as polyurethane or hybrid powder coatings), wood and fibrous substrates (such as textile, leather, carpet, paper). Preferably, the material for the article is selected from ceramics, glass (for example boroslicate glass, sodalime glass, aluminoslicate glass, or any other glass type), metals (such as aluminum, steel etc.), polymeric materials (such as poly(meth)acrylate, polycarbonate, polystyrene, styrene copolymers, such as styrene acrylonitrile copolymers, polyesters, polyethylene terephthalate), natural and man-made stone, more preferably from metals, ceramics, glass and polymeric materials (such as poly(meth)acrylate, polycarbonate, polystyrene, styrene copolymers, such as styrene acrylonitrile copolymers, polyesters, polyethylene terephthalate).

[0127] The coating according to the present invention is especially suitable for dark colored surfaces made of materials as described above, preferably for metal or anodized aluminum surfaces, but not limited to these.

[0128] Thickness and shape of the article may vary case by case and can be flat, 2D or 3D shape.

[0129] The article can have chemical, physical and / or mechanical surface treatments before the thin film is applied to the article such as deposited onto the article. In case of metal, for example aluminum, the article can be polished, anodized, colored, or coated with other coating(s) prior to material deposition.

[0130] Glass can be non-tempered, thermally, or chemically tempered and it can have different surface preparations including polishing, grinding, washing using various different surface treatment agents (alkaline or acidic).

[0131] Furthermore, the article can be either flat or can have a surface texture (example etched glass surface or anodized aluminium surface) in it or other layers on the article can provide the texturing / corru gated surface or no surface texture in it.

[0132] In case of glass the surface can be textured by using etching [e.g. to produce anti-glare (AG) effect on glass] or by applying coating layer to provide the AG effect.

[0133] The thin film can be directly applied onto the article as such that at least one surface of the article is in direct contact with the thin film.

[0134] The thin film can also be applied onto an intermediate layer as such that the inner surface of the intermediate layer is in direct contact with at least one surface of the article. The thin film is then in direct contact with the outer surface of the intermediate layer. The intermediate layer can have mechanical, physical, chemical, or optical function in connection with the material coating layer. The intermediate layer can be actual physical coating layer or can be a modification on molecular and or atomic level in the article in the area of the surface which is in direct contact with the intermediate layer.

[0135] Preferred variants and embodiments of the process of the present invention are also preferred variants and embodiments of the article according to the present invention.

[0136] It is preferred that a fingerprint on the coating of the article does not reflect light and therefore appears transparent. On an article having a black surface, the fingerprint on the coating appears in black colour.

[0137] Composition The present invention is further directed to a composition comprising a polysiloxane comprising at least two silane monomers according to formulas (I) and (II)

[0138] Si(O-R1)4(I) wherein R1is independently selected from a linear or branched alkyl group having 1 to 10, preferably 1 to 6, more preferably 1 or 2 carbon atoms; and

[0139] Ar-Si(R2)a(O-R3)3-a(II) wherein Ar is a substituted or unsubstituted aromatic group, preferably selected from a substituted or unsubstituted phenyl group, naphthyl group, anthracenyl group and phenanthrenyl group, more preferably an unsubstituted phenyl group;

[0140] R2is independently selected from hydrogen and a linear or branched hydrocarbyl group, preferably a linear or branched alkyl group having 1 to 10, more preferably 1 to 6, still more preferably 1 or 2 carbon atoms;

[0141] R3is independently selected from a linear or branched alkyl group having 1 to 10, preferably 1 to 6, more preferably 1 or 2 carbon atoms; and a is 0 or 1 , preferably 1 .

[0142] Preferred features of the process according to the present invention are also preferred features of the composition of the present invention.

[0143] It is especially preferred that the silane monomers of the polysiloxane are tetraethoxysilane, phenylmethyldimethoxysilane and optionally (3- glycidyloxypropyl)tri methoxysilane.

[0144] This composition is surprisingly stable at room temperature and slightly elevated temperature (up to 40°C).

[0145] The composition usually has a shelf life, determined as described in the experimental part of, of at least 6 months.

[0146] Use

[0147] The present invention is furthermore directed to the use of the composition as described above or below for preparing a coating on an article, preferably an invisible fingerprint coating on an article. Preferred features of the process, the composition, the thin film and the substrate according to the present invention are also preferred features of the use of the present invention.

[0148] Experimental part

[0149] Measuring methods

[0150] Molecular weight

[0151] The gel permeation chromatographic system consisted of a GPC apparatus eguipped with a Waters 1515 isocratic HPLC pump and a Waters 2414 refractive index detector. The polysiloxanes (0.20 g, 50% solid content) were dissolved in THF (HPLC grade; 2.30 g). The analyte injection volume was 100 pL, the flow was 0.70 mL min-1, and the column temperature was set to 40 °C. Four polysterene exclusion-based columns were used. The mobile phase was THF (HPLC grade). The weight-average molecular weight (Mw) of the polymers were determined using internal standards, e.g. two series of polystyrenes (Serie A: 5 polystyrenes with Mw= 120 000 g mol’1, 42 400 g mol’1, 10 700 g mol’1, 2 640 g mol’1, 474 g mol’1and Serie B: 4 polymers with Mw= 193 000 g mol’1, 16 700 g mol’1, 6 540 g mol’1, 890 g mol’1).

[0152] Solids content (Moisture analysis measurement)

[0153] The solid content of the polymers was determined using a Mettler Toledo HB43 instrument. The polymeric solution (0.9 - 1.1 g) to analyzed was placed in a measuring tray (disposable weighing / drying pan in aluminum). The aluminum pan was then heated by a halogen lamp for 10 min from room temperature to T = 160 °C. The mass of solid polymer present in the analyzed polymeric solution was determined after evaporation of the solvents.

[0154] Water contact angle (WCA), oil contact angle (OCA)

[0155] Film is prepared on pretreated (plasma) glass or anodized aluminum substrate by using a spray tool (Typical spray process: Scan speed: 300 mm / s; Pitch: 50 mm; Gap: 100 mm; Flow rate: 5-6 ml / min; Atomization air pressure: 5 kg / cm2), followed by thermal cure example at 150°C for 60 min (for glass and ceramic) and at 80°C for 60 min (for anodized aluminium). The static water contact angle (WCA) measurement is performed by optical tensiometer using distilled water, 4pl droplet size, three measurement points average is recorded as the measurement result value and Young-Laplace equation is used as the numerical method to describe the contour of the drop (Tool: Attension Theta optical tensiometer). Also other liquids can be used in addition to water, such as diiodomethane and hexadecane, to characterize the surface for the measurement of the oil contact angle (OCA).

[0156] Abrasion

[0157] Film is prepared on pretreated (plasma) glass, anodized aluminum, or ceramic substrate by using a spray tool (Typical spray process: Scan speed: 300 mm / s; Pitch: 50 mm; Gap: 100 mm; Flow rate: 5-6 ml / min; Atomization air pressure: 5 kg / cm2), followed by thermal cure example at 150°C for 60 min (for glass and ceramic) and at 80°C for 60 min (for anodized aluminium and other metal). Abrasion testing is carried out using Bon Star steel wool #0000, 1 kg load, 1x1 cm head (non-metal substrate) or 2x2 cm (metal substrate), 2-inch stroke, 60c / min speed. (Tools: Taber linear abraser, 5750). Abrasion test evaluation criteria: Initial water contact angle, water contact angle measurement at 50 cycle intervals (up to 300 cycles) and visual inspection for surface damage I visual scratch inspection at 50 cycle intervals (up to 300 cycles). Water contact angle is measured according to water contact angle measurement method and visual inspection is done under microscope inspection and green and red-light quality lamp inspection. In addition to steel wool, Cotton Cloth, Wool Felt and Minoan Eraser are also used to test the abrasion performance.

[0158] Invisibility of fingerprint and fingerprint colour

[0159] For determining the invisiblity of the fingerprint the following protocol was followed:

[0160] (a) Collect appropriate amount of oil from face, especially forehead and nose areas by rubbing fingers of both hands.

[0161] (b) Rub hands together to spread oils uniformly across the fingertips of both hands.

[0162] (c) Print three fingerprints at a time (using index, middle, and ring fingertips) onto the substrate by applying medium pressure. Both hands can be used to print two substrates simultaneously.

[0163] (d) Repeat steps (a) to (d) to print fingerprints onto all substrates considered. It is advised that maximum 10 substrates should be considered for testing as a group. Otherwise, there is a possibility of out-of-oil on the face to collect. (e) Fingerprint colour inspection and visibility ranking: Usually, D65 lighting or office lighting is recommended to inspect fingerprints’ colour [white or black (signified for transparent)], and three different angles are considered for observation (0°, 45°, and 90°). Visibility ranking is scale up from 0 - 3, invisible to easily visible from all angles.

[0164] (f) Clean fingerprints via one directional wiping with microfiber cloth (or similar). Count the number of wipes needed to clean each print. Wiped area has to be dried properly by cloth / towel prior to cleaning agent drying (e.g., lab-grade IPA) on surface to avoid streaking.

[0165] (g) Repeat steps (a) to (e) at least 3 times and report average values.

[0166] Invisibility of fingerprint: scale: 0 - 3 (0 is best; 3 is worst). 0 = no fingerprint seen; 1 = slight marking difficult to see from any angles (0°, 45°, 90°); 2 = some markings cannot be seen from every angle; 3 = visible from all angles.

[0167] The fingerprint colour is checked during the determination of invisibility of the fingerprint to appear white or black.

[0168] Thereby, white or black is the appearance of the fingerprint on the dark substrate (e.g. anodized aluminum substrate). If the oil of fingerprint can spread on the substrate, fingerprint does not reflect light and appears black as a colour on the dark substrate. Colour of the fingerprint: W = white; B = black.

[0169] The fingerprint was wiped with microfiber cloth using hand. The applied pressure is unknown, but minimal force (like common dust wiping cleaning procedure) has been used.

[0170] Scale is from A to C: cleanability of fingerprint with dry cloth. A = easy wiping; B = requires several wipes with high force; C = cannot be removed, it rather spread.

[0171] Chemical resistance

[0172] Four chemicals (1 = soft-soap, 2 = skin care cream, 3 = peroxide containing disinfectant and 4 = neutral hand sanitizer) have been tested for the determination of the chemical resistance properties of the coatings. Chemical 1 , 2 and 4 are applied on the coating using a cotton pad to cover a defined test area of 20 x 20 mm completely. The excess of chemical is removed with dry cotton pad. For chemical 3, the same procedure as above is conducted, but the cotton pad is replaced with wet wipe.

[0173] Test condition: the samples should be staged for at least 12h at room temperature, then the samples are put in a weather chamber (55 °C 185% RH) for 24h.

[0174] Washing procedure: the samples are taken out from the weather chamber and washed uing 5% fairy solution. The wiping should be done in circular motions.

[0175] Visual quality (VQ) inspection: cosmetic defects (paint peel, staining, discoloration etc...) are inspected using bear eyes. The graduation is as followed:

[0176] Water contact angle (WCA) measurement: KRUSS contact angle measurement device was used, the water droplet size was 4 pm, and the delay time was 15 s. Automatic baseline correction and ellipse method were employed for calculating the WCA. The experiment was repeated 4 times for each chemical applied areas.

[0177] Synthesis examples:

[0178] Abbreviations of components:

[0179] TEOS tetraethoxysilane n-hexylTEOS n-hexyltriethoxysilane

[0180] PMDMS phenylmethyldimethoxysilane

[0181] MEMO 3-trimethoxysilylpropyl methacrylate

[0182] TESE Bis(triethoxysilyl)ethane

[0183] F13 1 H, 1 H, 2H, 2H-perfluorooctyltrimethoxysilane GPTMS Glycidyloxypropyl)trimethoxysilane

[0184] MTEOS methyltriethoxysilane

[0185] PTMS phenyltrimethoxysilane

[0186] EtOH Ethanol

[0187] MeOH Methanol

[0188] H2O Water

[0189] DI-H2O deionized water

[0190] IPA 2-propanol

[0191] PGME propyleneglycolmonomethylether

[0192] PGMEA propyleneglycolmonomethyletheracetate

[0193] Novec 7100 mixture of isomers of methoxy-nonafluorobutane, commercially available from 3M

[0194] Novec 7200 mixture of isomers of ethoxy-nonfluorobutane, commercially available from 3M

[0195] Novec 7300 1 ,1 ,1 ,2,2,3, 4,5,5,5-decafluoro-3-methoxy-4-(trifluoromethyl)pentane, commercially available from 3M

[0196] MEK methyl ethyl ketone

[0197] EG ethylene glycol

[0198] PnB propylene glycol butyl ether

[0199] MTBE methyl tert.-butyl ether

[0200] KOH potassium hydroxide (0.1 M; aqueous solution)

[0201] HCOOH formic acid (0.1 M or 0.01 M; aqueous solution)

[0202] HNO3 nitric acid (0.1 M; aqueous solution)

[0203] DSX-E OPTOOL DSX E (fluoro polyether silane), commercially available from

[0204] Daikin

[0205] ZrO2 zirconium dioxide particles

[0206] PDS-1615 silanol terminated (14-18% diphenylsiloxane)-dimethylsiloxane copolymer, commercially available from Gelest Inc.

[0207] AQSF-2P500C2-081 / 0720 Aquashield forte (ceramic nanoparticles dispersed in an organic medium e.g. isopropanol), commercially available from TECNAN RT room temperature

[0208] Example 1 - comparative:

[0209] In a 3 necks round bottom flask, n-hexylTEOS (50 g; 0.20 mol) is mixed with EtOH (50 g). KOH (0.1 M; 40 g) is added dropwise. The reaction mixture was stirred at RT overnight. Then the solvents were evaporated yielding a white viscous liquid. The polymer (0.75 g) was mixed with PGME (66.35 g), Novec 7100 (70.77 g) and EG (3.52 g). The polymer did not dissolve in the reaction mixture, and it was not possible to coat the formulation on any substrates.

[0210] Example 2:

[0211] In a 250 mL round bottom flask, PMDMS (12.76 g; 0.075 mol) and TEOS (4.16 g; 0.03 mol) and n-hexylTEOS (2.48 g; 0.01 mol) are mixed in EtOH (19 g). HCOOH (0.1 M; aqueous solution; 9 g) is added dropwise and the reaction mixture is refluxed for 2h. After cooling to RT, PGME (30 g) was added and solvent exchange from EtOH I MeOH I H2O to PGME was performed. The solid content was found to be 25.86% and then was adjusted to 10% by addition of more PGME (59.65 g). The polymer (10.5 g; 10% solid content in PGME) was mixed with Novec 7100 (69.35 g), PGME (56.45 g) and EG (3.47 g)-

[0212] Example 3:

[0213] In a 250 mL round bottom flask, PMDMS (12.76 g; 0.075 mol) and TEOS (6.25 g; 0.03 mol) are mixed in EtOH (19 g). HCOOH (0.1 M; aqueous solution; 4.68 g) is added dropwise and the reaction mixture is refluxed for 2h. After cooling to RT, PGME (30 g) was added and solvent exchange from EtOH I MeOH I H2O to PGME was performed. The solid content was found to be 17.16% and then was adjusted to 10% by addition of more PGME (22.19 g). The polymer (10.5 g; 10% solid content in PGME) was mixed with Novec 7100 (69.35 g), PGME (56.45 g) and EG (3.47 g).

[0214] Example 4 - comparative:

[0215] In a 500 mL round bottom flask, BTESE (70 g; 0.2 mol) is mixed with acetone (180 g). HNO3 (0.1 M; 21.6 g) is added dropwise and the reaction mixture is refluxed for 1 h. After cooling to RT, PGME (180 g) was added and solvent exchange from EtOH I MeOH I H2O to PGME was performed. The solid content was found to be 25.55% and then was adjusted to 10% by addition of more PGME (217.7 g). The polymer (10.47 g; 10% solid content in PGME) was mixed with Novec 7100 (69.5 g), PGME (56.49 g) and EG (3.47 g)-

[0216] Example 5- comparative:

[0217] In a 500 mL round bottom flask, BTESE (70 g; 0.2 mol) is mixed with acetone (180 g). HNO3 (0.1 M; 21.6 g) is added dropwise and the reaction mixture is refluxed for 1 h. After cooling to RT, PGME (180 g) was added and solvent exchange from EtOH I MeOH I H2O to PGME was performed. The solid content was found to be 25.55% and then was adjusted to 10% by addition of more PGME (217.7 g). The polymer (10.47 g; 10% solid content in PGME) was mixed with MEK (38.61 g), PGME (87.61 g) and EG (3.58 g).

[0218] Example 6 - comparative:

[0219] In a 1 L round bottom flask, BTESE (120 g; 33.83 mmol), GPTMS (0.9 g; 0.38 mmol), F13 (6 g; 1.17 mmol) are mixed in IPA (126.9 g) and acetone (380.7 g). HNO3 (0.1 M; 73.2 g) is added dropwise and the reaction mixture is refluxed for 2h. After cooling to RT, PGME (200 g) was added and solvent exchange from EtOH I MeOH I H2O to PGME was performed. The solid content was found to be 36.35% and then was adjusted to 10% by addition of more PGME (463.2 g). The polymer (10.57 g; 10% solid content in PGME) was mixed with Novec 7100 (69.39 g), PGME (56.33 g) and EG (3.5 g)-

[0220] Example 7 - comparative:

[0221] In a 1 L round bottom flask, BTESE (120 g; 33.83 mmol), GPTMS (0.9 g; 0.38 mmol), F13 (6 g; 1.17 mmol) are mixed in IPA (126.9 g) and acetone (380.7 g). HNO3 (0.1 M; 73.2 g) is added dropwise and the reaction mixture is refluxed for 2h. After cooling to RT, PGME (200 g) was added and solvent exchange from EtOH I MeOH I H2O to PGME was performed. The solid content was found to be 36.35% and then was adjusted to 10% by addition of more PGME (463.2 g). The polymer (10.51 g; 10% solid content in PGME) was mixed with MEK (38.53 g), PGME (87.67 g) and EG (3.55 g).

[0222] Example 8:

[0223] In a 500 mL round bottom flask, PMDMS (36.44 g; 199 mmol), TEOS (41 .6 g; 199 mmol) are mixed in EtOH (78.04 g). HCOOH (0.1 M; 43.2 g) is added dropwise and the reaction mixture is refluxed for 2h. After cooling to RT, PGME (120 g) was added and solvent exchange from EtOH I MeOH I H2O to PGME was performed. The solid content was found to be 27.13% and then was adjusted to 10% by addition of more PGME (239.8 g). The polymer (10.56 g; 10% solid content in PGME) was mixed with Novec 7100 (69.72 g), PGME (56.39 g) and EG (3.48 g).

[0224] Example 9 - comparative:

[0225] In a 500 mL round bottom flask, PMDMS (70 g; 0.384 mol) is mixed with acetone (180 g). HNO3 (0.1 M; 13.82 g) is added dropwise and the reaction mixture is refluxed for 1 h. After cooling to RT, PGME (180 g) was added and solvent exchange from EtOH I MeOH I H2O to PGME was performed. The solid content was found to be 24.03% and then was adjusted to 10% by addition of more PGME (204 g). The polymer (10.48 g; 10% solid content in PGME) was mixed with Novec 7100 (69.63 g), PGME (56.44 g) and EG (3.51 g)-

[0226] Example 10 - comparative:

[0227] In a 500 mL round bottom flask, TEOS (43.44 g; mol) is mixed with ZrO2 (8.24 g; 50% wt in PGMEA) in acetone (137.00 g). HNO3 (0.1 M; 29.98 g) is added dropwise and the reaction mixture is refluxed for 2h. After cooling to RT, PGME (116 g) was added and solvent exchange from EtOH I acetone I H2O to PGME was performed. The solid content was found to be 21 .43% and then was adjusted to 10% by addition of more PGME (118 g). The polymer (10.52 g; 10% solid content in PGME) was mixed with Novec 7100 (70.01 g), PGME (56.39 g) and EG (3.51 g).

[0228] Example 11 - comparative:

[0229] In a 10L reactor, tetraethoxysilane (510.72 g) is mixed with acetone (1600 g). HNO3 (0.1 M; 353.28 g) is added dropwise and the reaction mixture is refluxed for 1 h. After cooling to room temperature, 1-methoxy-2-propanol (1600 g) is added and solvent exchange from EtOH I acetone I H2O to PGME is performed under reduced pressure. After moisture analysis, the solid content is adjusted to 10% by addition of 1 -methoxylpropanol. The polymer (75 g; 10% solid content in PGME) was mixed with Novec 7100 (495.5 g), PGME (402.7 g), DSX-E (2.5 g) and EG (24.8 g).

[0230] Example 12 - comparative: In a 10L reactor, tetraethoxysilane (510.72 g) is mixed with acetone (1600 g). HNO3 (0.1 M; 353.28 g) is added dropwise and the reaction mixture is refluxed for 1 h. After cooling to room temperature, 1-methoxy-2-propanol (1600 g) is added and solvent exchange from EtOH I acetone I H2O to PGME is performed under reduced pressure. After moisture analysis, the solid content is adjusted to 10% by addition of 1 -methoxylpropanol. The polymer (10.53 g; 10% solid content in PGME) was mixed with Novec 7100 (69.04 g), PGME (56.43 g) and EG (3.49 g).

[0231] Example 13:

[0232] In a 500 mL round bottom flask, PMDMS (27.30 g; 150 mmol) and TEOS (72.91 g; 350 mmol) are mixed in EtOH (100 g). HCOOH (0.1 M; 61 ,2 g) is added dropwise and the reaction mixture is refluxed for 2h. After cooling to RT, PGME (150 g) was added and solvent exchange from MeOH I EtOH I H2O to PGME was performed. The solid content was found to be 21 .98% and then was adjusted to 10% by addition of more PGME (227.26 g). The polymer (10.53 g; 10% in PGME) was mixed with Novec 7100 (69.78 g), PGME (56.47 g), EG (3.49 g) and PDS-1615 (0.7 g).

[0233] Example 14:

[0234] In a 500 mL round bottom flask, PMDMS (18.23 g; 100 mmol), TEOS (72.91 g; 350 mmol) and MEMO (12.41 g; 50 mmol) are mixed in EtOH (103 g). HCOOH (0.1 M; 63 g) is added dropwise and the reaction mixture is refluxed for 2h. After cooling to RT, PGME (150 g) is added and solvent exchange from MeOH I EtOH I H2O to PGME was performed. The solid content was found to be 26.71% and then was adjusted to 10% by addition of more PGME (254.00 g). The polymer (10.5 g; 10% in PGME) was mixed with Novec 7100 (69.71 g), PGME (56.58 g) and EG (3.5 g).

[0235] Example 15:

[0236] In a 500 mL round bottom flask, PMDMS (27.30 g; 150 mmol) and TEOS (72.91 g; 350 mmol) are mixed in EtOH (100 g). HCOOH (0.1 M; 61 ,2 g) is added dropwise and the reaction mixture is refluxed for 2h. After cooling to RT, PGME (150 g) was added and solvent exchange from MeOH I EtOH I H2O to PGME was performed. The solid content was found to be 21 .98% and then was adjusted to 10% by addition of more PGME (227.26 g). The polymer (10.54 g; 10% in PGME) was mixed with Novec 7100 (69.42 g), PGME (56.40 g), EG (3.54 g) and AQSF-2P500C2-081 / 0720 (0.35 g). Example 16:

[0237] In a 10L reactor, PMDMS (300.3 g; 1.64 mol) and TEOS (802.01 g; 3.85 mol) are mixed in EtOH (1 100 g). HCOOH (0.1 M; 673.2 g) is added dropwise and the reaction mixture is refluxed for 2h. After cooling to RT, PGME (1 7050 g) was added and solvent exchange from EtOH I MeOH I H2O to PGME was performed. The solid content was found to be 30.46% and then was adjusted to 10% by addition of more PGME (3 365 g). The polymer (10.48 g; 10% in PGME) was mixed with Novec 7100 (28.03 g), PGME (98.18 g) and EG (3.51 g).

[0238] Example 17:

[0239] In a 500 mL round bottom flask, PMDMS (27.3 g; 150 mmol) and TEOS (72.91 g; 350 mmol) are mixed in EtOH (100 g). HCOOH (0.1 M; 61.2 g) is added and the reaction mixture is refluxed for 2h. After cooling to RT, PGME (150 g) was added and solvent exchange from EtOH I MeOH I H2O to PGME was performed. The solid content was found to be 21 .98% and then was adjusted to 10% by addition of more PGME (227.26 g). The polymer (21 g; 10% in PGME) was mixed with Novec 7100 (139.45 g), PGME (112.76 g) and EG (6.95 g).

[0240] Example 18:

[0241] In a 500 mL round bottom flask, PMDMS (27.3 g; 150 mmol), TEOS (62.5 g; 300 mmol) and GPTMS (11.81 g; 50 mmol) are mixed in EtOH (101.61 g). HCOOH (0.1 M; 59.4 g) is added and the reaction mixture is refluxed for 2h. After cooling to RT, PGME (150 g) was added and solvent exchange from EtOH I MeOH I H2O to PGME was performed. The solid content was found to be 27.10% and then was adjusted to 10% by addition of more PGME (308 g). The polymer (75.13 g; 10% in PGME) was mixed with Novec 7100 (498.1 g), PGME (402.72 g) and EG (24.75 g).

[0242] Example 19:

[0243] In a 500 mL round bottom flask, PMDMS (27.3 g; 150 mmol), TEOS (62.5 g; 300 mmol) and GPTMS (11.81 g; 50 mmol) are mixed in EtOH (101.61 g). HCOOH (0.1 M; 59.4 g) is added and the reaction mixture is refluxed for 2h. After cooling to RT, PGME (150 g) was added and solvent exchange from EtOH I MeOH I H2O to PGME was performed. The solid content was found to be 27.10% and then was adjusted to 10% by addition of more PGME (308 g). The polymer (37.74 g; 10% in PGME) was mixed with Novec 7100 (100.12 g), PGME (350.08 g) and EG (12.42 g).

[0244] Example 20:

[0245] In a 500 mL round bottom flask, PMDMS (27.3 g; 150 mmol), TEOS (62.5 g; 300 mmol) and GPTMS (11.81 g; 50 mmol) are mixed in EtOH (101.61 g). HCOOH (0.1 M; 59.4 g) is added and the reaction mixture is refluxed for 2h. After cooling to RT, PGME (150 g) was added and solvent exchange from EtOH I MeOH I H2O to PGME was performed. The solid content was found to be 27.10% and then was adjusted to 10% by addition of more PGME (308 g). The polymer (37.55 g; 10% in PGME) was mixed with Novec 7100 (50.08 g), PGME (400.13 g) and EG (12.4 g).

[0246] Example 21:

[0247] In a 1 L round bottm flask, PMDMS (34.2 g; 187 mmol), TEOS (109.36 g; 525 mmol) and GPTMS (8.86 g; 37.5 mmol) are mixed in EtOH (152.15 g). HCOOH (0.1 M; 93.15 g) is added and the reaction mixture is refluxed for 2h. After cooling to RT, PGME (225 g) was added and solvent exchange from EtOH I MeOH I H2O to PGME was performed. The solid content was found to be 24.83% and then adjusted to 10% by addition of more PGME (385.58 g). The polymer (37.51 g; 10% in PGME) was mixed with Novec 7200 (100.02 g), PGME (350.02 g) and EG (16,81 g).

[0248] Example 22:

[0249] In a 500 mL round bottom flask, PMDMS (27.3 g; 150 mmol), TEOS (62.5 g; 300 mmol) and GPTMS (11.81 g; 50 mmol) are mixed in EtOH (101.61 g). HCOOH (0.1 M; 59.4 g) is added and the reaction mixture is refluxed for 2h. After cooling to RT, PGME (150 g) was added and solvent exchange from EtOH I MeOH I H2O to PGME was performed. The solid content was found to be 27.10% and then was adjusted to 10% by addition of more PGME (308 g). The polymer (37.6 g; 10% in PGME) was mixed with PGME (450.11 g) and EG (13.1 g).

[0250] Example 23:

[0251] In a 500 mL round bottom flask, PMDMS (27.3 g; 150 mmol), TEOS (62.5 g; 300 mmol) and GPTMS (11.81 g; 50 mmol) are mixed in EtOH (101.61 g). HCOOH (0.1 M; 59.4 g) is added and the reaction mixture is refluxed for 2h. After cooling to RT, PGME (150 g) was added and solvent exchange from EtOH I MeOH I H2O to PGME was performed. The solid content was found to be 27.10% and then was adjusted to 10% by addition of more PGME (308 g). The polymer (10.5 g; 10% in PGME) was mixed with MEK (69.73 g), PGME (56.4 g) and EG (3.53 g).

[0252] Example 24:

[0253] In a 500 mL round bottom flask, PMDMS (27.3 g; 150 mmol), TEOS (62.5 g; 300 mmol) and GPTMS (11.81 g; 50 mmol) are mixed in EtOH (101.61 g). HCOOH (0.1 M; 59.4 g) is added and the reaction mixture is refluxed for 2h. After cooling to RT, PGME (150 g) was added and solvent exchange from EtOH I MeOH I H2O to PGME was performed. The solid content was found to be 27.10% and then was adjusted to 10% by addition of more PGME (308 g). The polymer (10.5 g; 10% in PGME) was mixed with IPA (69.73 g), PGME (56.5 g) and EG (3.5 g).

[0254] Example 25 - comparative

[0255] In a 500 mL round bottom flask, GPTMS (7.09 g; 29.9 mmol), MTEOS (44.10 g; 247.3 mmol) and PTMS (4.46 g; 22.4 mmol) were mixed in IPA (55 g). HNO3 (0.1 M; 32,35 g) was added dropwise and the reaction mixture was refluxed for 2h. After cooling to RT, PnB (50 g) was added and solvent exchange from EtOH I MeOH I IPA I H2O to PGME was performed. The solid content was found to be 36.67% and then was adjusted to 10% by addition of more PnB (189 g). Then, triethylamine (0.08 g) was added, and the reaction mixture was stirred at T = 95 °C for 40 min. After cooling to RT, the reaction mixture was transferred to a separation funnel. MTBE (100 g) and DI-H2O (100 g) were added. After separation of the phases, the organic phase was washed with DI-H2O (4 x 50 g). PnB (50 g) was added to the organic phase and a new solvent exchange from MTBE I H2O I PnB to PnB was performed. The solid content was found to be 6.86%. CISi(CH3)3 (1% of solid: 0.08 g) was added and the reaction mixture was stirred at T = 105 °C for 90 min. The polymer (6.86% in PnB; 33.58 g) was mixed with Novec 7200 (60 g), PGME (198.97 g) and EG (7.44 g).

[0256] Process conditions and application examples:

[0257] Typical substrate clean procedure prior spray coating (example for glass):

[0258] Glass substrate must be free of stains, debris and any greasiness prior to coating; It is very important to get good wetting of the glass surface (glass surface water contact angle should be <5° prior coating; to ensure excellent coating performance and visual quality);

[0259] Step 1 : Liquid alkaline or acidic glass clean solution; non-foaming cleaning agent to be used in glass clean machinery;

[0260] Step 2: DI water clean step in glass clean machinery;

[0261] Step 3: Plasma / Corona treatment (If possible make water contact angle check <5°, as quality check) (In case of glass either a liquid clean and / or plasma clean steps can be used);

[0262] Optimize spray parameters to target cured film thickness of 40-100 nm; handle substrates with care not to damage wet coating when transfering to thermal cure; Step 5: Curing temperature 80-250°C; Curing time 30-60 minutes; no special atmosphere

[0263] Spray set-up and spray parameter:

[0264] Step 4: Spray Process; Optimize spray parameters to target cured film thickness of 40- 100 nm;

[0265] Curing conditions: handle substrates with care not to damage wet coating when transfering to thermal cure; Step 5: Curing temperature 70 to 200°C; Curing time 15 to 60 minutes; no special atmosphere

[0266] Application examples:

[0267] Films are prepared on hairline, anodized aluminum and dark substrates as described above.

[0268] The oil contact angles (OCA), the water contact angles (WCA), invisibility of fingerprints (IF), fingerprint colour (FC), easy to clean properties (E2C) and abrasion resistance of the cured films are shown in Table 1 .

[0269] Chemical resistance properties for a selected number of examples are listed in Table 2. Table 1

[0270] Table 2

Claims

Claims1 . A process for preparing a thin film on a substrate, the process comprising the steps of a) admixing at least two different silane monomers to a first solvent to form a mixture, with the proviso that• a first silane monomer is selected from compounds of formula (I)Si(O-R1)4(I) whereinR1is independently selected from a linear or branched alkyl group having 1 to 10, preferably 1 to 6, more preferably 1 or 2 carbon atoms; and• a second silane monomer is selected from compounds of formula (II)Ar-Si(R2)a(O-R3)3-a(II) whereinAr is a substituted or unsubstituted aromatic group, preferably selected from a substituted or unsubstituted phenyl group, naphthyl group, anthracenyl group and phenanthrenyl group, more preferably an unsubstituted phenyl group;R2is independently selected from independently selected from hydrogen and a linear or branched hydrocarbyl group, preferably a linear or branched alkyl group having 1 to 10, more preferably 1 to 6, still more preferably 1 or 2 carbon atoms;R3is independently selected from a linear or branched alkyl group having 1 to 10, preferably 1 to 6, more preferably 1 or 2 carbon atoms; and a is 0 or 1 , preferably 1 ; b) at least partially hydrolysing the silane monomers in the presence of a catalyst and polymerizing at least the silane monomers according to formulas (I) and (II) to obtain a composition comprising a polysiloxane comprising silane monomers according to formulas (I) and (II); c) optionally changing the first solvent to a second solvent; d) forming a thin layer from the composition obtained in step c), if present, or step b) on the substrate; e) optionally partially or completely removing solvent, if present, after step d);f) curing the intermediate product obtained in step e), if present, or step d), if step e) is not present, thereby obtaining a thin film.

2. The process according to claim 1 , wherein the first silane monomer is selected from tetramethoxysilane and tetraethoxysilane and mixtures thereof.

3. The process according to claims 1 or 2, wherein the second silane monomer is selected from phenylmethyldimethoxysilane, phenylmethyldiethoxysilane, phenylethyldimethoxysilane, phenylethyldiethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane and mixtures thereof, preferably phenylmethyldimethoxysilane, phenylmethyldiethoxysilane, phenylethyldimethoxysilane, phenylethyldiethoxysilane and mixtures thereof, more preferably phenylmethyldimethoxysilane, phenylmethyldiethoxysilane and mixtures thereof.

4. The process according to any one of claims 1 to 3, wherein in step a) additionally one or more silane monomers different from the first and second silane monomer of formulas (I) and (II) are admixed together with the first and second silane monomer of formulas (I) and (II) to the first solvent.

5. The process according to claim 4, wherein the one or more silane monomers different from the first and second silane monomer of formulas (I) and (II) are selected from (3-glycidyloxypropyl)trimethoxysilane (GPTMS), (3- glycidoxypropyl)triethoxysilane (GPTEOS), methyl triethoxysilane (MTEOS), n-octyl trimethoxysilane (n-octylTMS), n-propyl triethoxysilane (n-propylTEOS), n-hexyl triethoxysilane (n-hexylTEOS), dodecyl triethoxysilane (dodecylTEOS), 3-[Bis(2- hydroxyethyl)amino]propyl triethoxysilane (BHEAPTEOS), methyltrimethoxysilane (MTMS), dimethyldiethoxysilane (DMDEOS), 3-trimethoxysilylpropyl methacrylate (MEMO), Bis(triethoxysilyl)ethane) (BTESE), Bis(methyldiethoxysilyl)ethane (BMDESE), 1 H, 1 H, 2H, 2H-perfluorooctyltrimethoxysilane (F13), 1 H, 1 H, 2H, 2H- perfluorodecyltrimethoxysilane (F17), 11 -chloroundecyltriethoxysilane (CI(CH2)nTEOS); 2-(3.4-Epoxycyclohexyl)ethyl triethoxysilane (ECHETEOS), hydroxymethyl triethoxysilane (HMTEOS), N-(3-triethoxysilylpropyl)gluconamide (NGPTEOS), (phenanthrene-9-yl) triethoxysilane ((phenanthrene-9-yl)TEOS), n-octyltrimethoxysilane (n-octylTMS), n-hexyltrimethoxysilane (n-hexylTMS), octaethoxy-1 ,3,5-trisilapentane (OEOSTSP), aminopropyltriethoxysilane (APTEOS), aminopropyltrimethoxysilane (APTMS), diphenyldimethoxysilane (DPDMS), diphenyldiethoxysilane (DPDEOS), dimethyldimethoxysilane (DMDMS), dimethyldiethoxysilane (DMDEOS), (3-glycidoxypropyl)methyldimethoxysilane (MGPDMS), (3-glycidoxypropyl)methyldiethoxysilane (MGPDEOS), 1 ,4- Bis(triethoxysilyl)benzene (BTESB), 1 ,4-Bis(trimethoxysilyl)benzene (BTMSB), hexadecyltrimethoxysilane (HDCTMS) and mixtures thereof.

6. The process according to claims 4 or 5, wherein the one or more silane monomers different from the first and second silane monomer of formulas (I) and (II) comprise (3-glycidyloxypropyl)trimethoxysilane (GPTMS), (3-glycidoxypropyl)triethoxysilane (GPTEOS) and mixtures thereof.

7. The process according to any one of claims 1 to 6, wherein in step a) tetraethoxysilane, phenylmethyldimethoxysilane and optionally (3- glycidyloxypropyl)trimethoxysilane are admixed to a first solvent to form a mixture.

8. The process according to any one of claims 1 to 7, wherein the first solvent is selected from ethanol (EtOH), acetone, 2-propanol (IPA), 1 -propanol, propylene glycol methyl ether acetate (PGMEA), 1-methoxy-2-propanol (PGME), tetrahydrofuran (THF), and mixtures thereof and / or the second solvent is selected from 1-methoxy-2-propanol (PGME), methyl ethyl ketone (MEK), 2-propanol (IPA), Dipropylene glycol n-butyl ether (DPnB), Diethylene glycol mono-n-hexyl ether (DEnH), Diethylene glycol monobutyl ether (DEG monobutyl ether or DEGBE or DEnB), Diethylene glycol monoethyl ether (DEGEE), Dipropylene glycol (DiPG), toluene, propylene glycol methyl ether acetate (PGMEA), ethylene glycol (EG), 1- butanol, 2-butanol, tert-butanol, / so-butanol, propylene glycol butyl ether (PnB), methoxy-nonafluorobutane (Novec 7100), ethoxy-nonfluorobutane (Novec 7200), 1 ,1 ,1 ,2,2,3,4,5,5,5-decafluoro-3-methoxy-4-(trifluoromethyl)pentane (Novec 7300), and mixtures thereof.

9. The process according to any one of claims 1 to 8, wherein the film has a thickness of from 15 to 250 nm, more preferably from 30 to 200 nm.

10. An article, preferably an article with a coated metal or anodized aluminum surface, comprising the thin film obtainable by the process according to any one of claims 1 to 9 as a coating on at least one surface, preferably a coated metal or anodized aluminum surface of said article.11 . The article according to claim 10, wherein a fingerprint on the coating appears transparent.

12. The article according to claims 10 or 11 being a touch panel display, such as a handheld touch panel display or other interactive touch screen device, a tablet and laptop computer and mobile phone enclosure and cover, a console panel, a home appliance, a kitchen and other worktop surface, a solar panel screen, a window and an article with a metal surface.

13. A composition comprising a polysiloxane comprising at least two silane monomers according to formulas (I) and (II)Si(O-R1)4(I) wherein R1is independently selected from a linear or branched alkyl group having 1 to 10, preferably 1 to 6, more preferably 1 or 2 carbon atoms; and Ar-Si(R2)a(O-R3)3-a(II) whereinAr is a substituted or unsubstituted aromatic group, preferably selected from a substituted or unsubstituted phenyl group, naphthyl group, anthracenyl group and phenanthrenyl group, more preferably an unsubstituted phenyl group;R2is independently selected from independently selected from hydrogen and a linear or branched hydrocarbyl group, preferably a linear or branched alkyl group having 1 to 10, more preferably 1 to 6, still more preferably 1 or 2 carbon atoms;R3is independently selected from a linear or branched alkyl group having 1 to 10, preferably 1 to 6, more preferably 1 or 2 carbon atoms; and a is 0 or 1 , preferably 1 .

14. The composition according to claim 13, wherein the silane monomers of the polysiloxane are tetraethoxysilane, phenylmethyldimethoxysilane and optionally (3- glycidyloxypropyl)tri methoxysilane.

15. Use of the composition according to claims 13 or 14 for preparing a coating on an article, preferably an invisible fingerprint coating on an article.