WO2023198747A1

WO2023198747A1 - Flexible monolayered polysiloxane hard coating

Info

Publication number: WO2023198747A1
Application number: PCT/EP2023/059509
Authority: WO
Inventors: Tiina ALAHAIVALA; Rakib KABIR; Ari KÄRKKÄINEN; Sacha Legrand; Tiina LEPPÄJÄRVI; Kaisa MALO; Matti Pesonen; Mia VIRKKUNEN
Original assignee: Optitune Oy
Priority date: 2022-04-14
Filing date: 2023-04-12
Publication date: 2023-10-19
Also published as: TW202348433A

Abstract

The present invention relates to a layered structure comprising a flexible or bendable substrate layer (A) and a monolayer coating comprises a siloxane polymer, which comprises side chains comprising one or more fluorinated polymer groups, and a method for preparing said layered structure.

Description

Flexible monolayered polysiloxane hard coating

Technical background

Transparent plastics have been widely used as a core material in optical and transparent display industries. In particular, transparent plastics such as PET (polyethylene terephthalate), PI (polyimide), PC (polycarbonate) or PMMA (polymethyl methacrylate) have been applied in flexible electronics applications, including displays, optical lens, transparent boards, and automotive industries as a lightweight alternative to glass owing to the properties of high light transmittance and suitable refractive index. However, these plastics have the disadvantage of low abrasion resistance, because they have lower surface hardness than glass.

For increasing abrasion resistance and photopatternability hard coating films have been suggested, which are flexible and bendable. Suitable flexible hard coatings are for instance polysiloxane based flexible hard coatings as e.g. disclosed in WO 2019/193258.

Hard coatings have the drawback of reducing the visibility of e.g. the display due to an increased light reflection. In order to reduce light reflections antireflective coatings have been proposed as additional layer on hard coating layers in multilayer approaches.

For instance WO 2006/082701 Al discloses a two-layer coating on a transparent plastic film substrate with a first hard coating layer from a material which contains a (meth)acrylate group containing curable compound and a (meth)acrylate group-containing reactive silicone and a second antireflection (low refractive) coating layer from a material which contains a siloxane component containing compound.

Other two layer approaches of a hard coating layer and a low refractive layer are suggested e.g. in US 11,046,827 B2 and KR 2004-0076422A.

Even three-layer coatings of a hard coating layer, a high refractive layer and a low refractive layer have been suggested e.g. in JP 2001-293818A. Such multilayer approaches have the drawback of reduced scratch resistance and a mismatch of refractive indices, which results in a heavy rainbow pattern as discussed e.g. in as discussed in CN 206270519 U. On reason for the poor scratch resistance could be that the hard coating layer for improving scratch resistance is usually the inner layer in direct contact with the plastic substrate and the adhesion to the low refractive outer layer is rather weak.

When applying the low refractive layer as inner layer and the hard coating layer as outer layer as discussed in TW 2009-16818 A the coating shows good scratch resistance and lower rainbow pattern but does not address the problem of high reflectance.

As the multilayer structures have technical challenges, a more efficient method would be to decrease the reflectance and increase the scratch resistance in a single layer. Attempts to increase the low-refractive layer scratch-resistance has been performed by adding nanometer sized particles, such as silica or alumina, but affecting the scratch resistance and lowering the reflectance in a single layer has been challenging. The single-layer solution typically compromises both in optics and scratch resistance properties. TW 2014-11177 A describes a monolayer coating which contains a nanoparticle mixture and a binder, having a dry-etched surface, and exhibiting a moth-eye structure formed on the dry-etched surface. This creates a plurality of prismatic structures on the hard-coating surface. So, in addition to anti -reflective hard-coating having high level of nanoparticles, a dry-etching procedure is performed, nanoparticles acting as an etching mask, resulting in a surface having good adhesion properties for the possible external layers like printing inks.

Generally, when the refractive index is higher than 1.45, the refractive index difference between the plastic substrate and the hard-coating layer is not large and thus the effect of reflectance decreasement is not very big.

Thus, there is a need in the art for flexible coatings on transparent plastic substrates, which are flexible and show an improved balance of properties in regard of mechanical properties such as scratch resistance and optical properties such as a low refractive index for reducing light reflection.

In the present invention a monolayer coating is suggested which shows such an improved balance of properties. Said monolayer coating comprises a siloxane polymer which comprises side chains comprising one or more fluorinated polymer groups.

Summary of the invention

The present invention relates to a layered structure comprising

(A) a substrate layer; and

(B) a monolayer coating coated on at least one surface of the substrate layer (A), wherein the monolayer coating (B) comprises a siloxane polymer which comprises side chains comprising one or more fluorinated polymer groups; and the substrate layer (A) is flexible, bendable or both.

Further, the present invention relates to a method for producing a layered structure as described above or below comprising the following steps:

• Providing a composition comprising at least three different silane monomers, wherein at least one of the silane monomers includes an active group capable of achieving crosslinking to adjacent siloxane polymer, and at least one monomer comprising a fluorinated polymer group;

• Subjecting the composition to at least partial hydrolysis of the monomers to form a composition comprising a siloxane polymer comprising side chains comprising one or more fluorinated polymer groups;

• Providing a substrate which is flexible or bendable or both;

• Depositing the composition comprising the siloxane polymer comprising side chains comprising one or more fluorinated polymer groups onto at least one surface of the substrate to form a monolayer coating of the composition comprising the siloxane polymer;

• Cross-linking the siloxane polymer chains as to obtain a monolayer coating comprising a cross-linked siloxane polymer in adherent contact with the at least one surface of the substrate.

Still further, the present invention relates to a silane composition comprising, dispersed or dissolved in a solvent,

• at least three different silane monomers, wherein at least one of the silane monomers includes an active group capable of achieving cross-linking to adjacent siloxane polymer, and

• at least one monomer comprising a fluorinated polymer group; said composition being capable for forming upon polymerization a monolayer coating having a thickness of 1 to 50 pm, in particular about 5 to 20 pm on at least one surface of a substrate layer, which is flexible, bendable or both.

Additionally, the present invention relates to a process for producing a siloxane polymer comprising side chains comprising one or more fluorinated polymer groups comprising the following steps:

• Admixing the at least three different silane monomers and at least one monomer comprising a fluorinated polymer group in a first solvent to form a mixture;

• Subjecting the mixture to a at least partial hydrolysis of the monomers in the presence of a catalyst, whereby the hydrolysed monomers are at least partially polymerized and crosslinked

• Optionally changing the first solvent to a second solvent;

• Subjecting the mixture to further crosslinking by thermal or radiation initiation to form the siloxane polymer comprising side chains comprising one or more fluorinated polymer groups, said siloxane polymer being capable for forming a monolayer coating having a thickness of 1 to 50 pm, in particular about 5 to 20 pm on at least one surface of a substrate layer, which is flexible, bendable or both.

The silane composition, the siloxane polymer, its monomers, the monolayer coating and the substrate layer preferably are defined by all their embodiments and properties as described above and below.

The inventive monolayer coating shows an improved balance of properties in regard of mechanical properties, especially scratch resistance, and optical properties, especially a low refractive index. Due to using a monolayer coating no interlayer adhesion problems as in multilayer coatings occur.

“Monolayer coating” in the sense of the present invention means a coating on at least one surface of the substrate layer (A) which consists of a single layer.

The monolayer coating (B) being in adherent contact with at least one surface of the substrate layer (A) in the sense of the present invention means that there is no further coating layer or adhesive layer between the at least one surface of the substrate layer (A) and the monolayer coating (B).

Various exemplifying and non-limiting embodiments of the invention both as to constructions and to methods of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific exemplifying embodiments when read in connection with the accompanying drawings.

The verbs “to comprise” and “to include” are used in this document as open limitations that neither exclude nor require the existence of also un-recited features. The features recited in depending on claims are mutually free combinable unless otherwise explicitly stated. Description of the invention

The present technology provides for layered structures wherein a substrate layer (A) is provided with a monolayer coating comprising a siloxane polymer, which comprises side chains comprising one or more fluorinated polymer groups. The layered structure is “bendable” in the sense that it is capable of being bent about a mandrel, having a radius of curvature, without breaking.

The properties of bendability can be tested using a test involving infolding or out-folding of the layered structure about a mandrel as described in WO 2019/193258.

Substrate layer (A)

The substrate layer (A) can be any kind of substrates such as glass, quartz, silicon, silicon nitride, polymers, metals and plastics or mixtures thereof. Furthermore, the substrate layer (A) can also include number of different surfaces such as different oxides, doped oxides, semimetals and the like or mixture thereof.

Suitable polymers are e.g. thermoplastic polymers, such as polyolefins, polyesters, polyamides, polyimides, polycarbonates, acrylic polymers, such as poly(methylmethacrylate), and Custom Design polymers.

Especially preferred polymers are polymethylmethacrylate (PMMA), polyethyleneterephtalate (PET) and colorless polyimide (CPI).

The substrate layer (A) can be the outmost layer of a device or an internal layer of a single stack. The substrate layer (A) can be coated on one or both sides.

The substrate layer (A) preferably has a thickness of 10 to 500 pm, more preferably 20 to 400 pm.

The substrate layer (A) is flexible, bendable or both, such that it is capable of being bent about a mandrel having a first minimum radius of curvature without breaking. A layered structure of the present kind is in particular capable of being bent about a mandrel having a second minimum radius of curvature without breaking, said first minimum radius being smaller or equal to the second minimum radius of curvature.

Thereby, the layered structure is preferably bendable without crack formation in an outfolding motion for up to 20,000 times using a minimum radius of 2.5 mm.

Further, the layered structure is preferably bendable without crack formation in an infolding motion for up to 200,000 times using a minimum radius of 1.5 mm, preferably of 1.0 mm. Still further, the layered structure preferably does not show crack formation when elongated to 8% at an elongation rate of 0.25 inches/minute (0,64 cm/min).

The at least one surface of the substrate layer (A) can be modified before depositing the first composition onto at least one surface of the substrate to form a monolayer coating (B). The at least one surface of the substrate layer (A) can be modified physically or chemically. Suitable physical modifications are plasma treatment or corona treatment or similar treatments.

Suitable chemical modifications could be a chemical cleaning process for cleaning the at least one surface of the substrate layer (A).

By means of physical or chemical modification the at least one surface is preferably activated to promote adhesion between the substrate layer (A) and the first coating layer (B).

In one embodiment an optional coating composition is deposited onto the at least one surface of the substrate layer (A) as such that an optional additional coating layer is formed onto the at least one surface of the substrate layer (A). Said optional additional coating layer is then on one side in adherent contact with the at least one surface of the substrate layer (A) and on the other side in adherent contact with the monolayer coating (B).

“Adherent contact” in this regard means that there is no further coating layer or adhesive layer between the at least one surface of the substrate layer (A) and the optional additional coating layer and the optional additional coating layer and the monolayer coating (B). Said optional additional coating layer can have a thickness of 5 to 300 nm or a thickness of 300 nm to 5 pm.

Said optional additional coating layer is usually applied in specific cases such as promoting the adhesion between the substrate layer (A) and the monolayer coating (B), wetting of the monolayer coating (B), promoting the optical performance of the layered structure or promoting the mechanical performance of the layered structure.

It is, however, preferred that no optional additional coating layer is applied between the substrate layer and the monolayer coating (B).

Monolayer coating (B)

The layered structure comprises a monolayer coating coated on at least one surface of the substrate layer (A) so that the monolayer coating (B).

It is preferred that the monolayer coating (B) is in adherent contact with at least one surface of the substrate layer (A).

“Adherent contact” in this regard means that there is no further coating layer or adhesive layer between the monolayer coating (B) and the at least one surface of the substrate layer (A).

The monolayer coating (B) preferably has a thickness of 1 to 100 pm, preferably of 2 to 50 pm, more preferably 5 to 40 pm.

The monolayer coating (B) comprises a siloxane polymer, which comprises side chains comprising one or more fluorinated polymer groups.

Preferably the siloxane polymer comprises monomer units selected from at least two different silane monomers, wherein at least one of the silane monomers includes an active group capable of achieving cross-linking to adjacent siloxane polymer chains, and wherein the adjacent siloxane polymer chains are crosslinked by means of said an active groups. The siloxane polymer can comprise monomer units selected from 2 to 10, such as from 2 to 6, preferably from 2 to 4 different silane monomers. “Different” in this connection means that the silane monomers differ in at least one chemical moiety.

Active groups are preferably epoxy, alicyclic epoxy groups (e.g. glycidyl), vinyl, allyl, acrylate, methacrylate and silane groups and combinations thereof.

Thereby, the epoxy, alicyclic epoxy groups (e.g. glycidyl), vinyl, allyl, acrylate, methacrylate groups are capable of achieving cross-linking to adjacent siloxane polymer chains upon a thermal or radiation initiation, preferably in the presence of a suitable initiator such as a thermal or radical initiator.

Suitable thermal or radical initiators are preferably selected from tert-amyl peroxybenzoate, 4,4-azobis(4-cyanovaleric acid), l,l'-azobis(cyclohexanecarbonitrile), benzoyl peroxide, 2,2- bis(tert-butylperoxy)butane, 1 , 1 -bis(tert-butylperoxy)cyclohexane, 2,2'-azobisisobutyronitrile (AIBN), 2, 5 -bi s(tert-butylperoxy)-2, 5 -dimethylhexane, 2,5-bis(tert-Butylperoxy)- 2,5 - dimethyl-3 -hexyne, bis(l -(tert-butylperoxy)- 1 -methylethyl)benzene, 1 , l-bis(tert- butylperoxy)-3,3,5- trimethylcyclohexane, tert-butyl hydroperoxide, tert-butyl peracetate, tert-butyl peroxide, tert-butyl peroxybenzoate, tert-butylperoxy isopropyl carbonate, bumene hydroperoxide, byclohexanone peroxide, bicumyl peroxide, lauroyl peroxide, 2,4- pentanedione peroxide, peracetic acid or potassium persulfate. Especially preferred is 2,2'- azobisisobutyronitrile (AIBN).

The silane group is capable of achieving cross-linking to a carbon-carbon double bond, such as a vinyl or allyl group) of an adjacent siloxane polymer chains upon hydrosilylation, preferably in the presence of a suitable catalyst, such as a platinum (Pt)-based catalyst such as the Speier catalyst (EbPtCle.EEO), Karstedt’s catalyst (Pt(0)-l,3-divinyl-l, 1,3,3- tetramethyldisiloxane complex solution) or a rhodium (Rh)-based catalyst such as Tris(triphenylphosphine)rhodium (I) chloride. In one embodiment, the molar ratio between monomers containing a first active group, e.g. selected from epoxy, alicyclic epoxy groups (e. g. glycidyl), and vinyl and allyl groups, to monomers containing a second active group, e.g. selected from acrylate and methacrylate groups, varies in the range of 1 : 100 to 100: 1, in particular 1 : 10 to 10:1, for example 5: 1 to 1 :2 or 3 : 1 to 1: 1.

In some embodiments, the components containing the second active group also be selected from acrylate and metacrylate containing compounds other than silane monomers, such as tetraethylene glycol diacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, ditrimethylol propane tetraacrylate, dipentaerythritol pentaacrylate, and dipentaerythritol hexaacrylate and combinations thereof.

In some embodiments, the active group or active groups will be present in a concentration of about 1 to 35 % based on the molar portion of monomers.

Suitable silane monomers are preferably represented by formula (I) R¹aSiX4-a (I) wherein

R¹ is selected from hydrogen and a group comprising linear and branched alkyl, cycloalkyl, alkenyl, alkynyl, (alk)acrylate, epoxy, allyl, vinyl and alkoxy and aryl having 1 to 6 rings, and wherein the group is substituted or unsubstituted;

X is a hydrolysable group or a hydrocarbon residue; and a is an integer 1 to 3.

The hydrolysable group is in particular an alkoxy group (cf. formula II).

The alkoxy groups of R¹ and/or the hydrolysable group X can be identical or different and preferably selected from the group of radicals having the formula

-O-R² (II) wherein

R² stands for a linear or branched alkyl group having 1 to 10, preferably 1 to 6 carbon atoms, and optionally exhibiting one or two substituents selected from the group of halogen, hydroxyl, vinyl, epoxy and allyl. Most preferred are methoxy and ethoxy groups.

Especially preferred are di-, tri- or tetraalkoxysilanes comprising alkoxy groups according to formula (II).

Particularly suitable silane monomers are selected from the group of tetraethoxy silane (TEOS), tetramethoxysilane (TMS), methyltriethoxysilane (MTEOS), methyltrimethoxysilane (MTMS), dimethyldiethoxysilane (DMDEOS), dimethyldimethoxysilane (DMDMS), diphenyldimethoxysilane (DPDMS), 3-(Trimethoxysilyl)propylmethacrylate (MEMO), 3- (Triethoxysilyl)propylmethacrylate, 5-(Bicycloheptenyl)triethoxysilane (BCHTEOS), (3- Glycidoxypropyl)tri ethoxy silane, (3 -Glycidoxypropyl)trimethoxy silane (GPTMS), (Heptadecafluoro- 1 , 1 , 2, 2-tetrahydrodecyl)trimethoxy silane, (Heptadecafluoro- 1 , 1 ,2,2- tetrahydrodecyl)triethoxysilane (F 17), 1H, 1H,2H,2H-Perfluorododecyltriethoxysilane, 1H, 1H,2H,2H-Perfluorododecyltrimethoxysilane, 1H, 1H,2H,2H- Perfluorooctyltriethoxysilane, 1H, 1H,2H,2H-Perfluorooctyltrimethoxysilane, 1H, 1H,2H,2H- Perfluoropentyltriethoxysilane, 1H,1H,2H,2H-Perfluoropentyltrimethoxysilane, 1H, 1H,2H,2H-Perfluorotetradecyltriethoxysilane, 1H, 1H,2H,2H- Perfluorotetradecyltrimethoxysilane, allyltrimethoxysilane (allylTMS), allyltriethoxysilane (allylTEOS), vinyltrimethoxysilane (vinylTMS), vinyltriethoxysilane (vinylTEOS), (3- Glycidopropyl)dimethoxymethylsilane (Me-GPTMS), methacryloxypropylmethyldimethoxysilane (Me-MEMO), phenylmethyldimethoxysilane (PMDMS), Bis[(2,2,3,3,4,4-hexafluorobutyl)propanoic ester]-3- aminopropyltrimethoxy silane, [2-(3,4-Epoxycy cl ohexyl)ethyl]trimethoxy silane (ECTMS) and mixtures thereof. Preferred are silane monomers are selected from the group of 3- (Trimethoxysilyl)propylmethacrylate (MEMO) and (3-Glycidoxypropyl)trimethoxysilane (GPTMS).

Said silane monomers are preferably present in the siloxane polymer in a molar amount of 50 to 99.99 wt%, preferably of 60 to 99 wt%, still more preferably of 75 to 97 wt%.

In one embodiment the at least two different silane monomers of the first siloxane polymer (B-l) comprise at least one bi-silane.

Suitable bi-silanes are preferably represented by formula (III) (R³)₃Si-Y-Si(R⁴)₃, (III) wherein

R³ and R⁴ are independently selected from hydrogen and a group consisting of linear or branched alkyl, cycloalkyl, alkenyl, alkynyl, (alk)acrylate, epoxy, allyl, vinyl, alkoxy and aryl having 1 to 6 rings, and wherein the group is substituted or unsub stitued; and

Y is a linking group selected from bivalent unsubstituted or substituted aliphatic and aromatic groups, such as alkylene, arylene, -O-alkylene-O-; -O-arylene-O-; alkylene-O-alkylene, arylene-O-arylene; alkylene-Z¹C(=O)Z²-alkylene, arylene-Z¹C(=O)Z²-arylene and -O- alkylene-Z¹C(=O)Z²-alkylene-O-; -O-arylene-Z¹C(=O)Z²-arylene-O-, wherein Z¹ and Z² are each selected from a direct bond or -O-.

In the bivalent “alkylene” groups and other similar aliphatic groups, the alkyl residue (or residue derived from an alkyl moiety) stands for 1 to 10, preferably 1 to 8, or 1 to 6 or even 1 to 4 carbon atoms, examples include ethylene and methylene and propylene.

“Arylene” stands for an aromatic bivalent group containing typically 1 to 3 aromatic rings, and 6 to 18 carbon atoms. Such groups are exemplified by phenylene (e.g. 1,4-phenylene and 1,3-phenylene groups) and biphenylene groups as well as naphthylene or anthracenylene groups.

The alkylene and arylene groups can optionally be substituted with 1 to 5 substituents selected from hydroxy, halo, vinyl, epoxy and allyl groups as well as alkyl, aryl and aralkyl groups.

Preferred alkoxy groups contain 1 to 4 carbon atoms. Examples are methoxy and ethoxy.

The term “phenyl” includes substituted phenyls such as phenyltrialkoxy, in particular phenyltrimethoxy or tri ethoxy, and perfluorophenyl. The phenyl as well as other aromatic or alicyclic groups can be coupled directly to a silicon atom or they can be coupled to a silicon atom via a methylene or ethylene bridge.

Exemplary bi-silanes include 1,2-Bis(triethoxysilyl)ethane (BTESE), 1,2- Bis(trimethoxysilyl)ethane (MEOS) and mixtures thereof.

It is preferable to have the bi-silane present in the siloxane polymer in a molar amount of 0 to 35 wt%, preferably of 1 to 25 wt%, still more preferably of 3 to 20 wt%.

Additionally, the siloxane polymer comprises at least one, such as 1 to 10, preferably 1 to 6, more preferably 1 or 2, most preferably one monomer comprising a fluorinated polymer group.

Said monomer comprising a fluorinated polymer group is preferably selected from fluorinated polysiloxanes and modified perfluoropolyethers.

The modified perfluoropolyethers are preferably selected from silane modified perfluoropolyethers, carboxyester modified perfluoropolyethers, such as acrylate modified perfluoropolyethers and methacrylate modified perfluoropolyethers, epoxy-based perfluoropolyethers and mixtures thereof. Such fluorinated polysiloxanes and modified perfluoropolyethers can be commercially available from Shin-Etsu Subelyn® fluorinated anti-smudge coating components of the KY- 100 Series, such as KY-1900 and KY-1901, Shin-Etsu Subelyn® fluorinated anti-smudge additives of the KY-1200 Series, such as KY-1271, or Daikin fluorinated anti-smudge coating components of the OPTOOL Series such as OPTOOL UD-509, OPTOOL UD-120 and OPTOOL DSX.

Other suitable fluorinated polysiloxanes are for example poly(methyl-3,3,3- trifluoropropyl)siloxane having a molecular weight in the range of from 1500 to 20000 g/mol, preferably from 2000 to 15000 g/mol.

The at least one fluorinated monomer is preferably present in the siloxane polymer in a weight amount of 0.01 to 10 wt%, preferably of 0.02 to 7 wt%, still more preferably of 0.05 to 5 wt%.

It is especially preferred that the monomers are selected from mixture of two or more of the group of 1,2-Bis(triethoxysilyl)ethane (BTESE), 3-(Trimethoxysilyl)propylmethacrylate (MEMO), and (3 -Glycidoxypropyl)trimethoxy silane (GPTMS) and additionally a fluorinated monomer selected from KY-1900, and KY-1901, KY-1271, OPTOOL UD-509, OPTOOL UD-120, OPTOOL DSX or poly(methyl-3,3,3-trifluoropropyl)siloxane having a molecular weight in the range of from 1500 to 20000 g/mol, preferably from 2000 to 15000 g/mol .

The composition comprising the siloxane polymer is preferably formed by a method comprising the steps of

• Admixing the at least two different silane monomers and the at least one monomer comprising a fluorinated polymer group, preferably as described above or below, in a first solvent to form a mixture; • Subjecting the mixture to an at least partial hydrolysis of the monomers in the presence of a catalyst, whereby the hydrolysed monomers are at least partially polymerized and crosslinked;

• Optionally changing the first solvent to a second solvent;

• Optionally subjecting the mixture to further crosslinking by hydrosilylation, thermal or radiation initiation.

The first solvent is preferably selected from the group of acetone, tetrahydrofuran (THF), toluene, 1 -propanol, 2-propanol, methanol, ethanol, water (H2O), cyclopentanone, acetonitrile, propylene glycol propyl ether, methyl-tert-butylether (MTBE), propylene glycol monomethylether acetate (PGMEA), methyl ethyl ketone, methyl isobutyl ketone, propylene glycol monomethylether (PGME) and propylene glycol propyl ether (PnP).

The monomers can be admixed in the first solvent at any suitable temperature for solving the monomers. Usually, room temperature suffices.

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

Suitable catalysts are acidic catalysts, basic catalysts or other catalysts.

Acidic catalysts are preferably selected from nitric acid (HNO3), sulfuric acid (H2SO4), formic acid (HCOOH), hydrochloric acid (HC1), sulfonic acid, hydrogen fluoride (HF), acetic acid (CH3COOH), trifluoromethanesulfonic acid or -toluene sulfonic acid. Especially preferred acidic catalysts are nitric acid (HNO3) and hydrochloric acid (HC1).

Basic catalysts are preferably selected from triethylamine (TEA), ammonium hydroxide (NH4OH), tetraethylammonium hydroxide (TEAH), tetramethylammonium hydroxide (TMEA), l,4-diazabicyclo[2.2.2]octane, imidazole and diethylenetriamine. Other catalysts are preferably selected from 2,2,3,3,4,4,5,5-octafluoropentylacrylate, poly(ethylene glycol) 200, poly(ethylene 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.

During the hydrolysis step the monomers are at least partially hydrolysed. Said at least partially hydrolysed monomers then are at least partially polymerized, preferably by condensation polymerization and crosslinked to form a siloxane polymer, which comprises side chains comprising one or more fluorinated carbon groups.

Said siloxane polymer usually has a relatively low molecular weight in range of about 500 to 30000 g/mol.

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

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 monomers. In addition, it improves the properties of the final siloxane polymer solution when used as coating layer(s) on the substrate.

The second solvent is preferably selected from the group of propylene glycol methyl ether (PGME), propylene glycol methyl ether acetate (PGMEA), 1 -ethanol, 2-ethanol (IP A), acrylonitrile diacetone alcohol (DAA), methyl isobutyl ketone (MIBK) or propylene glycol n- propyl ether (PnP). 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 hydrosilylation, thermal or radiation initiation.

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.

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

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

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

To improve resolution of the material when applied to photolithography, 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 not affecting any of the active groups intended for the UV curing can be employed. To mention an example, hydrosilylation for example using a proton on one chain reacting with a double bond on another chain will achieve cross-linking of desired kind. Another example is cross-linking through double bonds or epoxy groups.

Different active groups are preferably used for cross-linking. Thus, the cross-linking of the siloxane polymer can be achieved with an active group having double bonds or epoxy groups or both, such as epoxy, vinyl or allyl or methacrylate group using radical initiators and photoacid generators. Epoxy groups can be employed for UV-curing and vice versa. The proportion of active groups required for cross-linking is generally smaller than for UV curing, e.g. about 0.1 to 10 mol%, based on the monomers, for cross-linking and about 5 to 50 mol%, based on the monomers, for UV curing.

The amount of the initiator added to the reaction mixture/ solution is generally about 0.1 to 10 wt%, preferably about 0.5 to 5 wt%, calculated from the total weight of the siloxane polymer.

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 2000 g/mol, the crosslinking will increase it above 3000, preferably to 4000 to 20000 g/mol.

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, methylfluorodimethoxy silane ((MeO)2SiFCH3), 3 -chloropropyltrimethoxy silane (Cl(CH2)3Si(OMe)3), ethyltrimethoxysilane (ETMS), or trimethylchlorosilane (CISiMes) in presence of a catalyst such as tri ethylaluminium (TEA) or imidazole. The amount of catalyst varies from 1.5 to 2 wt% of total solid. The reaction time varies from 40 to 45 min.

Other additives typically introduced into the first composition comprising the third siloxane polymer (D-l) include chemicals that can further modify the final surface properties of coated and cured film or improve wettability/adhesion properties of the coating layer (B) to the substrate layer (A) or the other coating layer (C) or improve coating drying and packing behavior during deposition and drying to reach good visual quality.

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-331, BYK-333, BYK-341, BYK- 345, BYK-348, BYK-377, BYK-378, BYK-381, BYK-390, BYK-3700, all commercially available from BYK Chemie GmbH.

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.

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.

By adjusting the hydrolysis and condensation conditions it is possible to control the concentration/ content of the group capable of being deprotonated (e. g. an OH-group) and any residual leaving groups from the silane precursors (e.g. alkoxy groups) of the siloxane polymer composition and also to control the final molecular weight of the siloxane polymer. This greatly affects dissolution of the siloxane polymer material into the aqueous based developer solution. Furthermore, the molecular weight of the polymer also greatly effects on the dissolution properties of the siloxane polymer into developer solutions.

Thus, for example, it has been found that when the final siloxane polymer has a high content of hydroxyl groups remaining and a low content of alkoxy (e.g. ethoxy) groups, the final siloxane polymer can be dissolved into an alkaline-water developer solution (e.g. tetra methyl ammonium hydroxide; TMAH, or potassium hydroxide; KOH).

On the other hand, if the remaining alkoxy-group content of the final siloxane polymer is high and it contains hardly any OH-groups, the final siloxane polymer has a very low solubility in an alkaline-water developer of the above kind. The OH-groups or other functional groups, such as amino (NH2), thiol (SH), carboxyl, phenol or similar that result in solubility to the alkaline developer systems, can be attached directly to the silicon atoms of the siloxane polymer backbone or optionally attached to organic functionalities attached into the siloxane polymer backbone to further facilitate and control the alkaline developer solubility.

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.

Usually, a further amount of an initiator molecule compound is added to the siloxane composition after synthesis. The initiator, which can be optionally similar to the one added during polymerization, is used for creating a species that can initiate the polymerization of the “active” functional group in the UV curing step. Thus, in case of an epoxy group, cationic or anionic initiators can be used. In case of a group with double bonds as “active” functional group in the synthesized material, radical initiators can be employed. Also, thermal initiators (working according to the radical, cationic or anionic mechanism) can be used to facilitate the crosslinking of the “active” functional groups. The choice of a proper combination of the photoinitiators and sensitizers also depends on the used exposure source (wavelength). Furthermore the selection of the used sensitizer depends on the selected initiator type. The concentration of the thermal or radiation initiator and sensitizers in the composition is generally about 0.1 to 10 %, preferably about 0.5 to 5 %, calculated from the mass of the siloxane polymer.

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.

The composition comprising the siloxane polymer as described above is deposited onto the onto at least one surface of the substrate layer (A) to form a monolayer coating (B).

It is preferred that the monolayer coating (B) is in adherent contact with the at least one surface of the substrate layer (A).

Suitable deposition methods include spin-on, clip, spray, ink-jet, roll-to-roll, gravure, reverse gravure, bar coating, slot, flexo-graphic, curtain, screen printing coating methods, extrusion coating, dip coating, flow coating or slit coating.

The deposited composition forms the monolayer coating (B) on the surface of the substrate layer (A). Typically, after deposition, or during the deposition step, the solvent is evaporated and the monolayer coating (B), preferably by thermal drying or optionally by vacuum and/or thermal drying combined. This step is also referred to as pre-curing.

In a second, subsequent step the monolayer coating (B) is cured to final hardness by using UV exposure followed by thermal curing at elevated temperature. In one embodiment, the pre-curing and the final curing steps are combined by carrying out heating by using an increasing heating gradient. In addition to the thermal cure only process, the curing can be performed in three steps, the process comprising thermal pre-cure and UV- cure followed by final thermal cure. It is also possible to apply a two step curing process where thermal pre-cure is followed by UV-cure. In such a case no final thermal cure is preferably applied after UV-cure.

According to a particular embodiment the method further includes developing the deposited film. In one embodiment, developing comprises exposing (full area or selective exposure using photomask or reticle or laser direct imaging) the deposited first siloxane polymer composition to UV light. The step of developing is typically carried out after any pre-curing step and before a final curing step.

Thus, in one embodiment the method comprises the steps of

- pre-curing or drying the monolayer coating (B) deposited on at least one surface of the substrate layer (A); optionally exposing the thus obtained monolayer coating (B); optionally developing the thus obtained monolayer coating (B); and curing the monolayer coating (B).

Exemplary epoxy -functional group containing monomers include (3- glycidoxypropyl)trimethoxysilane, l-(2-(Trimethoxysilyl)ethyl)cyclohexane-3,4-epoxide, (3- glycidoxypropyl)tri ethoxy silane, (3- glycidoxypropyl)tripropoxy silane, 3- glycidoxypropyltri(2-methoxyethoxy)silane, 2,3 -epoxypropyltri ethoxy silane, 3,4- epoxybutyltriethoxysilane, 4,5- epoxypentyltriethoxysilane, 5,6-epoxyhexyltriethoxysilane, 5,6- epoxyhexyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane, 2-(3,4- epoxy cy cl ohexyl)ethyltrimethoxy silane, 4-(trimethoxy silyl)butane- 1 ,2-epoxide. Further examples of functionalized compounds are acrylate and metacrylate compounds, such as tetraethylene glycol diacrylate, trimethylo Ipropane triacrylate, pentaerythritol triacrylate, ditrimethylolpropane tetraacrylate, dipentaerythritol pentaacrylate, and dipentaerythritol hexaacrylate and combinations thereof. Such compounds can be used as part of the silane compositions.

According to a particular embodiment the method further includes curing the composition.

The thickness of the monolayer coating (B) on the at least one surface of the substrate layer (A) (i.e. the film thickness) may range from 1 to 100 pm, preferably of 2 to 50 pm, more preferably 5 to 40 pm.

The monolayer coating (B) preferably is a flexible hard coat layer.

It is preferred that the pencil hardness of the monolayer coating (B) is at least 2H, more preferably 3H, still more preferably at least 4H, as determined by ASTM D3363-00, Elcometer tester.

Preferably the monolayer coating (B) has an adhesion of 4B-5B, as tested by ASTM D3359- 09, Cross-Hatch tester.

Further, the monolayer coating (B) preferably has scratch resistance as evidenced by no visual scratches on a Taber linear abrasion test (Using Linear Abraser from Taber Industries) carried out at up to 2000 linear cycles with BonStar steel wool #0000, at 1kg weight, 2x2 cm head size, 2.0 inch stroke length, 60 cycles/min and Rubber abrasion test.

Still further, the monolayer coating (B) preferably has a scratch resistance as evidenced by no visual scratches in a Minoan rubber abrasion test using TABER ® Linear Abraser-Model 5750, Minoan rubber, 1 kg weight lead, 40 cycles / min, 1000 cycles.

Layered structure The layered structure according to the present invention comprises the substrate layer (A) and the monolayer coating (B). The monolayer coating (B) is preferably the outermost layer of the layered structure and preferably in adherent contact with at least one surface of the substrate layer (A). This means that no further coatings or coating layers are applied on the at least one surface of the substrate layer (A).

The layered structure shows a good balance of properties of adhesion of the different layers to each other, high scratch resistance and low reflectance.

The layered structure of preferably shows a scratch resistance of no visual scratches in a Taber linear abrasion test (Using Linear Abraser from Taber Industries) carried out at up to 2000 linear cycles with BonStar steel wool #0000, at 1kg weight, 2x2 cm head size, 2.0-inch stroke length, 60 cycles/min.

Still further, the layered structure preferably has a scratch resistance as evidenced by no visual scratches in a Minoan rubber abrasion test using TABER ® Linear Abraser-Model 5750, Minoan rubber, 1 kg weight lead, 40 cycles / min, 1000 cycles.

Further the layered structure preferably has a water contact angle (WCA) of at least 95°, more preferably at least 98°, still more preferably at least 100° in a Taber linear abrasion test (Using Linear Abraser from Taber Industries) carried out at up to 2000 linear cycles with BonStar steel wool #0000, at 1kg weight, 2x2 cm head size, 2.0-inch stroke length, 60 cycles/min.

Still further, the layered structure preferably has a water contact angle (WCA) of at least 90 in a Minoan rubber abrasion test using TABER ® Linear Abraser-Model 5750, Minoan rubber, 1 kg weight lead, 40 cycles / min, 1000 cycles. Additionally, the layered structure preferably shows a refractive index of from 1.40 to 1.55, more preferably from 1.45 to 1.50.

Further, the layered structure preferably shows a transmittance of at least 89.5%, more preferably from 89.8% to 90.5% at a wavelength of 550 nm, when measured on a coated colorless polyimide (CPI) 50-micron film.

The layered structure preferably shows an increase of transmittance of from 0.5 to 1.5%, compared to the uncoated CPI film at a wavelength of 550 nm.

Still further, the layered structure preferably shows a transmittance of at least 90.8%, more preferably from 90.9% to 91.5% at a wavelength of 550 nm, when measured on a coated polyethylene terephthalate (PET) 50 micron film.

The layered structure preferably shows an increase of transmittance of from 0.2 to 1.0%, compared to the uncoated PET film at a wavelength of 550 nm.

Additionally, the layered structure preferably has a haze of not more than 0.5%, preferably from 0.1 to 0.4%, when measured on a coated colorless polyimide (CPI) film.

Still further, the layered structure preferably has a haze of not more than 0.8%, preferably from 0.2 to 0.6%, when measured on a coated polyethylene terephthalate (PET) film.

The layered structure is preferably capable of being bent about a mandrel having a radius of curvature without breaking, as evidenced as a value of less than 0.8 cm, in particular less than 0.4 cm, on an outfolding mandrel diameter test.

The layered structure according to the present invention is suitable for flexible electronics applications, including displays, optical lens, transparent boards, and automotive industries especially as a lightweight alternative to glass.

The present invention is further characterized by the following non-limiting examples: Examples:

Determination methods

Molecular weight: the polymers were characterized by gel permeation chromatography. The chromatographic system consisted of a GPC apparatus equipped with an isocratic HPLC pump and a 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, and the column temperature was set to 40 °C. Four polysterene exclusion-based columns were used. The mobile phase was THF (HPLC grade). Number-average molecular weight (Mn) and the weight-average molecular weight ( ) of the polymers were determined using internal standards, e.g. two series of polystyrenes (Serie A: 5 polystyrenes with M_w = 120.000 g/mol, 42.400 g/mol, 10.700 g/mol, 2.640 g/mol, 474 g/mol and Serie B: 4 polymers with Mr = 193.000 g/mol, 16.700 g/mol, 6.540 g/mol, 890 g/mol).

Solid contents: The solid content of the polymers was determined using a Mettler Toledo HB43 instrument. The sample was weighted on aluminum dish / cup and the measurement was performed using about 1 g of material.

Viscosity: the used tool was a Grabner Instruments Viscometer MINIVIS-II. The used method was “falling ball viscosity measurement”. Samples were measured at T = 20 °C by using a stell ball with3.175 mm diameter.

Film thickness and refractive index (RI): the film thickness and refractive index were measured using Ellipsometer UVISEL-VASE Horiba Jobin-Yvon. Measurements are performed using Gorilla Glass 4 or silicon wafer (diameter: 150 mm, Type/Dopant: P/Bor, Orientation: <l-0-0>, Resistivity: 1-30 Q.cm, thickness: 675 +/- 25 pm, TTV: < 5 pm, particle: < 20 @ 0,2 pm, Front surface: polished; back surface: etched; Flat 1 SEMI standard) or other suitable substrates. The material fil could be prepared on pre-treated (plasma) glass substrate ny using a spray tool (typical sprat 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 T = 150 °C for 60 min.

Transmission (T%) and reflection (R%): A Konica Minolta spectrophotometer CM-3700A (Specta Magic NX software) was used to measure transmittance and reflectance.

Color and Haze measurement: L*(D 65), a*(D 65) and b*(D 65) and Haze were determined by using A Konica Minolta spectrophotometer CM-3700A (Specta Magic NX software)

Pencil hardness (PEHA): the pencil hardness was determined according to ASTM standard D3363-00 using a Elcometer pencil hardness tester.

Water contact angle (WCA): the static contact angle measurement was performed by optical tensiometer using distilled water, 4 pL droplet size, three measurement points average was recorded as the measurement result value and Young-Laplace equation was used as the numerical method to describe the contour of the drop (tool: attention theta optical tensiometer).

Abrasion: abrasion testing was carried out using for example Bon Star steel wool #000, 1 kg load, 1 x 1 cm head, 2.0-inch stroke, 60 cycles / min speed, using taber linear abraser 5750 and using TABER ® Linear Abraser-Model 5750, Minoan rubber, 1 kg weight lead, 40 cycles / min, 1000 cycles.

Visual quality (VQ): the visual inspection can be observed with bare eyes, under microscope using a green or red-light quality lamp inspection. The visual quality can be scored between 0 (best) to 3 (worse). Adhesion: the adhesion was determined according to ASTM standard D3359-D9 using a Elcometer cross-hatch tester and Elcometer tape test.

Preparation examples

Example 1: FlexHC with KY1900

In a 500 mL round bottom flask, BTESE (5,3g; 0,0150 mol), GPTMS (22,8 g; 0.0965 mol), MEMO (9,25 g; 0,0372 mol), KY1900 (0,5g) are mixed in Acetone (28g; 0.4821 mol). HNO3 (0,lM; 9,5 g; 0,5278 mol) is added dropwise over 15 min and the reaction mixture is stirred at room temperature overnight. PGME (7,8 g; 0,086 mol) is added and solvent exchange procedure from acetone to PGME was performed.

Example 2: FlexHC with KY1900 (different amount)

In a 500 mL round bottom flask, BTESE (5,3g; 0,0150 mol), GPTMS (22,8 g; 0.0965 mol), MEMO (9,25 g; 0,0372 mol), KY1900 (1,0g) are mixed in Acetone (28g; 0.4821 mol). HNO3 (0,lM; 9,5 g; 0,5278 mol) is added dropwise over 15 min and the reaction mixture is stirred at room temperature overnight. PGME (7,8 g; 0,086 mol) is added and solvent exchange procedure from acetone to PGME was performed.

Example 3: FlexHC with KY1900 in IPA instead of acetone (solubility issues of KY1900 in acetone)

In a 500 mL round bottom flask, BTESE (5,3g; 0,0150 mol), GPTMS (22,8 g; 0.0965 mol), MEMO (9,25 g; 0,0372 mol), KY1900 (0,5g) are mixed in IPA (26,25g; 0.4368 mol). HNO3 (0,lM; 8,87 g; 0,4928 mol) is added dropwise over 15 min and the reaction mixture is stirred at room temperature overnight. PGME (27,26 g; 0,3024 mol) is added and solvent exchange procedure from acetone to PGME was performed.

Example 4: FlexHC with KY1900 in IPA (KY1900 added in 2^nd step) In a 500 mL round bottom flask, BTESE (5,3g; 0,0150 mol), GPTMS (22,8 g; 0.0965 mol), MEMO (9,25 g; 0,0372 mol) are mixed in IPA (26,25g; 0.4368 mol). HNO₃ (0,lM; 8,87 g; 0,4928 mol) is added dropwise over 15 min and the reaction mixture is stirred at room temperature overnight. KY1900 (0.15g) added HNO3 (0,lM; 1,0 g; 0,0556 mol) dropwise. After 1 hour, PGME (27,26 g; 0,3024 mol) is added and solvent exchange procedure from acetone to PGME was performed.

Example 5: FlexHC with OPTOOL DSX in IPA

In a 500 mL round bottom flask, BTESE (5,3g; 0,0150 mol), GPTMS (22,8 g; 0.0965 mol), MEMO (9,25 g; 0,0372 mol), OPTOOL DSX (0,2g) are mixed in IPA (26,25g; 0.4368 mol). HNO3 (0,lM; 8,87 g; 0,4928 mol) is added dropwise over 15 min and the reaction mixture is stirred at room temperature overnight. PGME (27,26 g; 0,3024 mol) is added and solvent exchange procedure from acetone to PGME was performed.

Example 6: FlexHC with poly(methyl-3,3,3-trifluoropropyl)siloxane Mw = 2400

In a 500 mL round bottom flask, BTESE (21.15 g; 0.06 mol), GPTMS (91,0 g; 0,3850 mol), MEMO (37g; 0,1490 mol), poly(methyl-3,3,3-trifluoropropyl)siloxane (2,0 g) are mixed in Acetone (130,77g; 2,8373 mol) were mixed in Acetone (112 g; 1,9353 mol). HNO3 (0,lM; 35,47 g; 1,9706 mol) is added dropwise over 15 min and the reaction mixture is stirred overnight at room temperature. PGME (90 g; 0,9986 mol) is added and solvent exchange procedure from acetone to PGME was performed.

Example 7: FlexHC with poly(methyl-3,3,3-trifluoropropyl)siloxane Mw = 14000

In a 500 mL round bottom flask, BTESE (21.15 g; 0.06 mol), GPTMS (91,0 g; 0,3850 mol), MEMO (37g; 0,1490 mol), poly(methyl-3,3,3-trifluoropropyl)siloxane (2,0 g) are mixed in Acetone (130,77g; 2,8373 mol) were mixed in Acetone (112 g; 1,9353 mol). HNO3 (0,lM; 35,47 g; 1,9706 mol) is added dropwise over 15 min and the reaction mixture is stirred overnight at room temperature. PGME (90 g; 0,9986 mol) is added and solvent exchange procedure from acetone to PGME was performed. Example 8: FlexHC with KY1271

In a 500 mL round bottom flask, BTESE (24,0 g; 0.0677 mol), GPTMS (100 g; 0,4231 mol), MEMO (40g; 0.1611 mol), KY1271 (0.1 wt% to 2,5 wt%) are mixed in Acetone (160g; 2,75 mol). HNO3 (0,lM; 35,2 g; 1,9556 mol) is added dropwise over 15 min and the reaction mixture is stirred at room temperature overnight. PGME (140 g; 1,553 mol) is added and solvent exchange procedure from acetone to PGME was performed.

Example 9: FlexHC with OPTOOL UD-509 & UD-120

In a 500 mL round bottom flask, BTESE (24,0 g; 0.0677 mol), GPTMS (100 g; 0,4231 mol), MEMO (40g; 0.1611 mol), OPTOOL (0.1 wt% to 2,5 wt%) are mixed in Acetone (160g; 2,75 mol). HNO3 (0,lM; 35,2 g; 1,9556 mol) is added dropwise over 15 min and the reaction mixture is stirred at room temperature overnight. PGME (140 g; 1,553 mol) is added and solvent exchange procedure from acetone to PGME was performed.

Application examples

Inventive coating:

The composition of example 9 comprising the polymer of BTESE, GPTMS, MEMO and 0.5 wt% KY1271 in PGME was mixed with 1% BYK333 and 1% BYK067A in order to obtain the coating composition.

Coating:

The coating compositions were deposited onto a polyethyleneterephtalate (PET) film 50 pm and on a colorless polyimide (CPI) film 50 pm and cured.

The coating and curing compositions were as follows: for PET film: 120 degree celcius/90 sec, UV-500W (90sec), 120 degree celcius/10 min, bar coater #4 (for thick film- 7-8 pm) or Mayer rod for CPI film: 120-140 degree celcius /90 sec, UV-500W (90sec), 140 degree celcius /10 min, bar coater #4 (for thick film- 7-8 m)

Abrasion test: The coated PET and CPI films were subjected to a steelwool abrasion test and Minoan rubber abrasion test. After 400, 800 1200, 1600 and 2000 cycles in the steelwool abrasion test and after 1000 cycles in the Minoan rubber abrasion test visual quality and the water contact angle were determined. The results are shown in Table 1 below.

ble 1 : Results of abrasion test, comparison of visual quality (VQ) and water contact angle (WCA)

Optical properties:

Figure 1 shows the transmittance of the CPI film coated with the inventive coating compared with uncoated CPI film. The coated CPI film shows a higher transmittance compared to the uncoated CPI film (bare CPI).

5

Figure 2 shows the transmittance of the PET film coated with the inventive coating compared with uncoated PET film. The coated PET film shows a higher transmittance compared to the uncoated PET film (bare PET).

10 Table 2 shows the optical properties and pencil hardness of the inventive coating on PET and CPI films compared with uncoated PET and CPI films.

Table 2: Optical properties and PEHA of the inventive coating on PET and CPI films compared with uncoated PET and CPI films

15

Claims

Claims A layered structure comprising

(A) a substrate layer; and

(B) a monolayer coating coated on at least one surface of the substrate layer (A), wherein the monolayer coating (B) comprises a siloxane polymer, which comprises side chains comprising one or more fluorinated polymer groups; and the substrate layer (A) is flexible, bendable or both. The layered structure according to claim 1, wherein the siloxane polymer comprises monomer units selected from at least two different silane monomers, wherein at least one of the silane monomers includes an active group capable of achieving cross-linking to adjacent siloxane polymer chains, and at least one monomer comprising a fluorinated polymer group and wherein the adjacent siloxane polymer chains are crosslinked by means of said an active groups and, wherein at least two different silane monomers preferably comprise at least one bi-silane. The layered structure according to claim 2, wherein at least two different silane monomers are selected from tetraethoxysilane (TEOS), tetramethoxysilane (TMS), methyltriethoxysilane (MTEOS), methyltrimethoxysilane (MTMS), dimethyldi ethoxy silane (DMDEOS), dimethyldimethoxy silane (DMDMS), diphenyldimethoxysilane (DPDMS), 3-(Trimethoxysilyl)propylmethacrylate (MEMO), 3-(Triethoxysilyl)propylmethacrylate, 5- (Bicycloheptenyl)triethoxysilane (BCHTEOS), (3- Glycidoxypropyljtriethoxysilane, (3-Glycidoxypropyl)trimethoxysilane (GPTMS), (Heptadecafluoro- 1 , 1 , 2, 2-tetrahydrodecyl)trimethoxy silane, (Heptadecafluoro- 1 , 1 ,2,2-tetrahydrodecyl)triethoxysilane (F 17), 1H, 1H,2H,2H- Perfluorododecyltri ethoxysilane, 1H, 1H,2H,2H- Perfluorododecyltrimethoxysilane, 1H,1H,2H,2H-Perfluorooctyltriethoxysilane, 1H, 1H,2H,2H-Perfluorooctyltrimethoxysilane, 1H, 1H,2H,2H- Perfluoropentyltriethoxysilane, 1H,1H,2H,2H-Perfluoropentyltrimethoxysilane, 1H, 1H,2H,2H-Perfluorotetradecyltriethoxysilane, 1H, 1H,2H,2H- Perfluorotetradecyltrimethoxysilane, allyltrimethoxysilane (allylTMS), allyltri ethoxy silane (allylTEOS), vinyltrimethoxy silane (vinylTMS), vinyltriethoxysilane (vinylTEOS), (3-Glycidopropyl)dimethoxymethylsilane (Me-GPTMS), methacryloxypropylmethyldimethoxysilane (Me-MEMO), phenylmethyldimethoxysilane (PMDMS), Bis[(2,2,3,3,4,4- hexafluorobutyl)propanoic ester]-3-aminopropyltrimethoxysilane, 1,2- Bis(triethoxysilyl)ethane (BTESE), 1,2-Bis(trimethoxysilyl)ethane (MEOS), [2- (3, 4-Epoxycyclohexyl)ethyl]trimethoxy silane (ECTMS) and mixtures thereof. The layered structure according to claims 2 or 3, wherein at least one monomer comprising a fluorinated polymer group is selected from fluorinated polysiloxanes, modified perfluoropolyethers and mixtures thereof, wherein the modified perfluoropolyethers are preferably selected from silane modified perfluoropolyethers, carboxyester modified perfluoropolyethers, such as acrylate modified perfluoropolyethers, methacrylate modified perfluoropolyethers, epoxy-based perfluoropolyethers and mixtures thereof. The layered structure according to any one of claims 1 to 4, wherein the monolayer coating (B) has a thickness of 1 to 100 pm, preferably of 2 to 50 pm, more preferably 5 to 40 pm. The layered structure according to any one of claims 1 to 5, wherein the material of the substrate layer (A) is selected from the group of glass, quartz, silicon, silicon nitride, polymers, metals and plastics and combinations thereof, wherein the material of the substrate layer (A) is preferably selected from oxide, doped oxide, semimetal and mixtures thereof, wherein the plastics are preferably selected from thermoplastic polymers, such as polyolefins, polyesters, polyamides, polyimides, polycarbonates, acrylic polymers, such as poly(methylmethacrylate), and Custom Design polymers., and wherein substrate layer (A) preferably has a thickness of 10 to 500 pm, preferably 20 to 400 pm. The layered structure according to any one of claims 1 to 6, having one or more, preferably all of the following properties:

• a pencil hardness of at least 2H, as determined by ASTM D3363-00, Elcometer tester; and/or

• an adhesion of 4B-5B, as tested by ASTM D3359-09, Cross-Hatch tester; and/or

• a scratch resistance as evidenced by no visual scratches on a Taber linear abrasion test (Using Linear Abraser from Taber Industries) carried out at up to 2000 linear cycles with BonStar steel wool #0000, at 1kg weight, 2x2 cm head size, 2.0 inch stroke length, 60 cycles/min; and/or

• a scratch resistance as evidenced by no visual scratches in a Minoan rubber abrasion test using TABER ® Linear Abraser-Model 5750, Minoan rubber, 1 kg weight lead, 40 cycles / min, 1000 cycles; and/or

• a water contact angle of at least 95° on a Taber linear abrasion test (Using Linear Abraser from Taber Industries) carried out at up to 2000 linear cycles with BonStar steel wool #0000, at 1kg weight, 2x2 cm head size, 2.0 inch stroke length, 60 cycles/min; and/or

• a water contact angle (WCA) of at least 90° in a Minoan rubber abrasion test using TABER ® Linear Abraser-Model 5750, Minoan rubber, 1 kg weight lead, 40 cycles / min, 1000 cycles; and/or

• a refractive index of from 1.40 to 1.55; and/or

• a transmittance of at least 89.5% at a wavelength of 550 nm, when measured on a coated colorless polyimide (CPI) film; and/or • an increase of transmittance of from 0.5 to 1.5%, compared to the uncoated CPI film at a wavelength of 550 nm; and/or

• a haze of not more than 0.5%, when measured on a coated colorless polyimide (CPI) film; and/or

• a transmittance of at least 90.8% at a wavelength of 550 nm, when measured on a coated polyethylene terephthalate (PET) film; and/or

• an increase of transmittance of from 0.2 to 1.0%, compared to the uncoated PET film at a wavelength of 550 nm; and/or

• a haze of not more than 0.8%, when measured on a coated polyethylene terephthalate (PET) film. A method for producing a layered structure according to any one of claims 1 to 7 comprising the following steps:

• Providing a composition comprising at least three different silane monomers, wherein at least one of the silane monomers includes an active group capable of achieving cross-linking to adjacent siloxane polymer, and at least one monomer comprising a fluorinated polymer group;

• Providing a substrate which is flexible or bendable or both;

• Cross-linking the siloxane polymer chains as to obtain a monolayer coating comprising a cross-linked siloxane polymer in adherent contact with the at least one surface of the substrate. The method according to claim 8, wherein the composition comprising a siloxane polymer comprising side chains comprising one or more fluorinated polymer groups is formed by

• Admixing the at least two different silane monomers and at least one monomer comprising a fluorinated polymer group in a first solvent to form a mixture;

• Subjecting the mixture to an at least partial hydrolysis of the monomers in the presence of a catalyst, whereby the hydrolysed monomers are at least partially polymerized and cross-linked;

• Optionally changing the first solvent to a second solvent;

• Subjecting the mixture to further crosslinking by thermal or radiation initiation. The method according to claim 9, wherein the mixture is further cross-linked by thermal initiation in the presence of a thermal initiator selected from tert-amyl peroxybenzoate, 4,4-azobis(4-cyanovaleric acid), 1,1'- azobis(cyclohexanecarbonitrile), benzoyl peroxide, 2,2-bis(tert- butylperoxyjbutane, l,l-bis(tert-butylperoxy)cyclohexane, 2,2'- azobisisobutyronitrile (AIBN), 2,5-bis(tert-butylperoxy)-Z,S-dimethylhexane, 2,5-bis(tert-Butylperoxy)- 2,5 -dimethyl-3 -hexyne, bis(l -(tert-butylperoxy)- 1 - methylethyljbenzene, l,l-bis(tert-butylperoxy)-3,3,5- trimethylcyclohexane, tert-butyl hydroperoxide, tert-butyl peracetate, tert-butyl peroxide, tert-butyl peroxybenzoate, tert-butylperoxy isopropyl carbonate, bumene hydroperoxide, byclohexanone peroxide, bicumyl peroxide, lauroyl peroxide, 2,4- pentanedione peroxide, peracetic acid or potassium persulfate, preferably 2,2'- azobisisobutyronitrile (AIBN). 11. The method according to claim 9 or 10, wherein the thermal cross-linking is in the range of about 30 to 200 °C, typically cross-linking is carried out at refluxing conditions of the solvent.

12. The method according to any one of claims 8 to 11, wherein the composition is deposited by spin-on, clip, spray, ink-jet, roll-to-roll, gravure, reverse gravure, bar coating, slot, flexo-graphic, curtain, screen printing coating methods, extrusion coating or slit coating.

13. The method according to any of claims 8 to 12, wherein the active group is epoxy, glycidyl, vinyl, allyl, acrylate or methacrylate group or a combination thereof.

14. A silane composition comprising, dispersed or dissolved in a solvent,

15. A process for producing a siloxane polymer comprising side chains comprising one or more fluorinated polymer groups comprising the following steps:

• Admixing the at least three different silane monomers and at least one monomer comprising a fluorinated polymer group in a first solvent to form a mixture; • Subjecting the mixture to a at least partial hydrolysis of the monomers in the presence of a catalyst, whereby the hydrolysed monomers are at least partially polymerized and cross-linked

• Optionally changing the first solvent to a second solvent; • Subjecting the mixture to further crosslinking by thermal or radiation initiation to form the siloxane polymer comprising side chains comprising one or more fluorinated polymer groups, said siloxane polymer being capable for forming a monolayer coating having a thickness of 1 to 50 pm, in particular about 5 to 20 pm on at least one surface of a substrate layer, which is flexible, bendable or both.