EP1572819A1

EP1572819A1 - Silicone composition for anti-mist and/or anti-fouling hard coating, based on colloidal silica, curable by cationic process

Info

Publication number: EP1572819A1
Application number: EP03815084A
Authority: EP
Inventors: Martial Deruelle; Jean-Marc Frances; Michel Feder
Original assignee: Rhodia Chimie SAS
Current assignee: Elkem Silicones France SAS
Priority date: 2002-12-16
Filing date: 2003-12-08
Publication date: 2005-09-14
Also published as: US8328929B2; AU2003296771A1; CN1735667A; WO2004063300A1; JP2006511673A; CN101851467A; US20080064832A1; FR2848563B1; JP4191141B2; US20060040113A1; FR2848563A1

Abstract

The invention concerns compositions crosslinkable by cationic process into hard coating, exhibiting moreover antifouling and/or anti-mist properties. Said composition, comprising non functionalized silica colloidal particles, further comprises: at least one crosslinkable and/or polymerisable silicone monomer, oligomer and/or polymer comprising: at least one unit of formula (I)<: >Z<1>(R<0>)aSiO(3-a)/2, wherein: a = 0, 1 or 2; R<0>, identical or different when a>1, represents an alkyl, cycloalkyl, aryl, vinyl, hydrogeno, alkoxy radical, preferably a C1-C6 lower alkyl<; >Z<1>, identical or different when the number of unit of formula (I) is greater than 1, is an organic substituent comprising at least one epoxy, and/or alkenylether and/or oxetane and/or dioxolane and/or carbonate reactive function, and preferably Z<1> being an organic substituent comprising an epoxy, and/or dioxolane reactive function; and a total number of silicon atoms per molecule not less than 2; and an efficient amount of at least one cationic initiator; optionally at least one organic solvent.

Description

SILICONE COMPOSITION FOR HARD COATING, BASED ON COLLOIDAL SILICA, CATIONICALLY CURABLE, ANTI-FOG AND / OR

ANTIFOULING

The field of the present invention is that of compositions which can be crosslinked cationically in a scratch-resistant hard coating. More preferably, the present invention relates to compositions which can be crosslinked cationically with a hard coating, moreover having anti-fouling and / or anti-fogging properties.

Thermoplastic materials, such as polycarbonate, have taken a prominent place in many applications, as glass substitutes. This is the case, for example, in the automotive field, where they are used for the manufacture of lenses for headlight optics and rear lights of vehicles. This is also the case in the field of eyewear where they are used for the production of spectacle lenses. The main advantage of these thermoplastic materials is that they are lighter and less brittle than glass.

However, these materials also have a major drawback, namely their low hardness compared to that of glass. As a result, these materials are more easily subject to scratching and alteration, even under normal use.

There has therefore been a need to find solutions intended to limit these scratching and alteration problems.

One of the solutions implemented consists in producing a hard coating on the surface of the thermoplastic material, in the form of a transparent laminate intended to improve the performance of the thermoplastic material. Numerous prior art documents describe compositions intended to form this type of coating. Compositions based on thermally crosslinkable epoxyalkoxysilanes are described in US Pat. No. 4,211,823. These compositions make it possible to obtain hard polysiloxane coatings. A notable drawback of these compositions is the time required for crosslinking.

Document WO-A-94/10230 proposes an improvement to avoid excessively long crosslinking times. This improvement consists in using the ultraviolet rays as a means of activating the crosslinking. However, a disadvantage of these compositions is that they have lower abrasion resistance than that of thermally crosslinked coatings.

To overcome this drawback, patent application WO-A-02/00561 claims a method for manufacturing a coating obtained by crosslinking, cationically, of a epoxy monomer essentially based on glycidyl first by photopolymerization, then by thermal post-crosslinking in the presence of a thermal crosslinking catalyst.

An American patent US-B-6,210,790 claims a colloidal silica modified by epoxy or propenyl ether groups and introduced into compositions crosslinkable by cationic route in hard coating. Colloidal silica is grafted with alkoxysilane in water. In addition to the silica functionalized with the alkoxysilane, the composition comprises multifunctional monomers and in particular siloxane monomers with epoxy units and a cationic initiator of the onium salt type.

A drawback of the technique described in this patent is on the one hand that it involves the prior functionalization of the colloidal silica with an alkoxysilane and on the other hand that it is necessary to remove the solvent for functionalization of the silica before crosslinking.

In addition, industries in the technical fields considered are waiting for hard coatings which also have anti-fog and / or anti-fouling properties.

Some previous documents describe means for obtaining anti-fogging or anti-fouling properties have already been described.

This is the case in particular of document WO-A-02/12404, which describes a hard coating based on colloidal silicas functionalized by acrylates for optical devices, having anti-fouling properties by means of a layer of perfluoropolyether, deposited on the hard coating.

Document FR-A-2 749 587 describes a composition crosslinkable by radiation with a hard coating having anti-fog properties. This composition comprises a colloidal silica, an olefin comprising at least two unsaturations and at least one divalent oxyalkylene radical, and a trialkoxysilane with an olefinic functional group.

The main anti-fog coating obtained from the composition described in document FR-A-2,749,587 has the main drawback of being sensitive to inhibition by oxygen in the air.

However, no composition of the prior art is capable of providing a hard coating having jointly anti-fog and anti-fouling properties. Indeed, it turns out that the mechanisms of anti-fog and anti-fouling properties are generally incompatible.

In this state of affairs, a first objective of the present invention is to provide a new cationically curable composition in a hard coating.

Another object of the present invention is to provide a composition capable of forming a hard coating having anti-fogging and / or anti-fouling properties. Another objective of the present invention is to provide a composition capable of forming a coating whose anti-fog and / or anti-fouling properties are long-lasting.

These objectives, among others, are achieved by the present invention which relates to a cationically crosslinkable composition with a hard coating, comprising colloidal particles of non-functionalized silica, characterized in that it additionally comprises:

at least one monomer, oligomer and / or crosslinkable and / or polymerizable silicone polymer comprising:

> at least one motif of formula (I):

Z (R) _a SiO ₍₃ _ _{a) / 2} / _d *. in which: - a = 0, 1 or 2,

- R °, identical or different when a> l, represents an alkyl, cycloalkyl, aryl, vinyl, hydrogen, alkoxy radical, preferably a lower Cι-C ₆ alkyl,

- Z ¹ , identical or different when the number of units of formula (I) is greater than 1, is an organic substituent comprising at least one reactive epoxy, and / or alkenylether and / or oxetane and / or dioxolane and / or carbonate function , and preferably Z ¹ being an organic substituent comprising at least one reactive epoxy and / or dioxolane function,> and a total number of silicon atoms per molecule at least equal to 2, and

- An effective amount of at least one cationic initiator, optionally at least one organic solvent.

By hard coating is meant a coating whose pencil hardness is at least equal to H.

Advantageously, this composition also comprises, as anti-fogging compound, at least one monomer, oligomer and / or crosslinkable and / or polymerizable silicone polymer comprising at least one unit of formula (II):

Z (R) _a SiO _(3. _{A) / 2}

(II) in which - a = 0, 1 or 2,

- R ° is as defined above,

- Z ² , identical or different when the number of units of formula (II) is greater than 1, is an organic substituent comprising at least one oxyalkyl or polyoxyalkyl function ((CH) _m O) _x or (CH ₂ -CH (CH ₃ ) -O) _y or copolymers, said monomer, oligomer and / or polymer having a viscosity of less than 500 mPa-s ^"1 and preferably less than 300 mPa.s ^{" 1} .

An effective compound may be, for example, a mixture of a silicone-polyether block copolymer and of free polyether, sold under the reference Rhodorsil® oil 10646.

An effective organic compound can also be a vinyl ether sold under the reference Rapicure® DPE2 (CAS N ° 765-12-8), DVE3 (CAS N ° 114188-95-3), or DPE3 (114266-85-2). It participates in effect in cationic polymerization and is integrated into the network making the treatment very effective.

Other anti-fog compounds can be, for example, sodium sulfosuccinate. It may also be any surfactant comprising hydrophilic groups such as polyoxyethylene, polyoxypropylene, sulfate, sulfonate or carboxylate of alkali metals, polyols, amine salts, quaternary amines.

Even more advantageously, the composition according to the invention comprises, as anti-fouling compound, at least one monomer, oligomer and / or crosslinkable silicone polymer and / or polymerizable comprising at least one unit of formula (III):

in which :

- a = 0, 1 or 2,

- R °, identical or different, represents an alkyl, cycloalkyl, aryl, vinyl, hydrogen, alkoxy radical, preferably a C ₁ -C ₆ lower alkyl,

- Z ³ , identical or different when the number of units of formula (III) is greater than 1, is an organic substituent comprising at least group (C _n F _2n + ι) - (R °) _a with n <20 and or a perfluoropolyether compound of formula (IV):

Y- (C _a F _2a O) _b -C _a F _2a -Y (IN)

in which : Y is a polymerizable group or a fluorine or hydrogen atom, a is between 1 and 7,

- b is between 1 and 300, so that said perfluoropolyether compound has an average molecular weight between 500 and 20,000.

The most effective organic compounds are:

- perfluorinated compounds containing an epoxy function or vinyl ether, such as glycidyloctafluoropentylether the glycidyltetrafluoroethylether, glycidyl Tetrafluoropropylether, the glycidylhexa-decafluorononyl the glycidyldodecafluoroheptylether the heptadecafluorononyloxirane the heptafluorobutyloxirane the hexadecafluorononylether the hexadecafluoro8- (trifluoromethyl ) nonyloxirane, dodecafluoroόtrifluoromethylheptyloxirane, octafluoropentanol, heptadecafluorononanol, heptadecafluoro- decanol ... - Asahi Glass products such as C ₈ Fπ oxirane

Thus, the perfluoropolyether compound can be taken from the group comprising: (C ₂ H ₅ O) ₂ CH ₃ SiC ₃ H ₆ NHCO (CF ₂ O) i ₅ (C ₂ F ₄ O) ₁₃ CF ₂ CONHC ₃ H ₆ SiCH ₃ (OC ₂ H ₅ ) ₂ , (C ₂ H ₅ O) ₃ SiC ₃ H ₆ NHCO (CF ₂ O) ₁₅ (C ₂ F ₄ O) ₁₃ CF ₂ CONHC ₃ H ₆ Si (OC ₂ H5) ₃ , F (CF (CF ₃ ) CF ₂ O) ₂₅ CF ₂ CF ₃ , C ₄ H ₉ NHCO (CF ₂ O) ι ₅ (C ₂ F ₄ O) ι ₃ CF ₂ CONHC ₄ Hg, CH ₂ = CHCOOC ₂ H ₄ NHCO (CF ₂ O) i5 (C ₂ F ₄ O) ι ₃ CF ₂ CONHC ₂ H ₄ OOCCH = CH ₂ ,

CH ₂ = CHCOOCH ₂ (CF ₂ O) ₁₅ (C ₂ F ₄ O) ι ₃ CF ₂ CH ₂ OOCCH = CH ₂ , (HOCH ₂ ) ₂ CH ₂ NHCO (CF ₂ O) ι ₅ (C ₂ F ₄ O ) ₁₃ CF ₂ CONHCH ₂ (CH ₂ OH) ₂ , (C ₂ H ₅ O) ₃ Si (CH ₂ ) ₃ NHCO (CF ₂ CF ₂ O) ₈ CF ₂ CONH (CH ₂ ) ₃ Si (OC ₂ H ₅ ) ₃ , (C ₂ H ₅ O) ₂ CH ₃ Si (CH2) ₃ NHCO (CF ₂ CF ₂ O) ₈ CF ₂ CONH (CH ₂ ) ₃ SiCH3 (OC ₂ H ₅ ) 2, (C ₂ H ₅ O ) ₂ CH ₃ Si (CH ₂ ) ₃ NHCO (CF ₂ CF ₂ O) ι ₄ CF ₂ CONH (CH ₂ ) ₃ SiCH ₃ (OC ₂ H ₅ ) ₂ ,

(C ₂ H ₅ O) ₃ Si (CH ₂ ) ₃ NHCO (CF ₂ C (CF ₃ ) FO) ι ₂ CF ₂ CONH (CH ₂ ) ₃ Si (OC ₂ H ₅ ) ₃ , (C ₂ H ₅ O ) ₂ CH ₃ Si (CH ₂ ) ₃ NHCO (CF ₂ C (CF ₃ ) FO) ι ₂ CF ₂ CONH (CH ₂ ) ₃ SiCH ₃ (OC ₂ H ₅ ) ₂ θu OOCCH = CH ₂ OOCCH = CH ₂

H ₂ C * = HCCOO-CH ₂ CHCH ₂ NHCO (CF ₂ 0) ι ₅ (CF ₂ CF ₂ 0) ι ₃ CF ₂ CONHCH ₂ CHCH ₂ -OOCCH = CH _2.

According to a first embodiment, the cationic initiator can be chosen from those whose cationic entity is selected from onium salts of formula (V):

[(R ¹ ) _n - A - (R ² ) _m (V)

in which : • A represents an element from groups 15 to 17 such as for example: I, S, Se, P orN,

R ¹ represents a C 6 -C 20 carbocyclic or heterocyclic aryl radical, said heterocyclic radical possibly containing nitrogen or sulfur as heteroelements,

• R ² represents RI or a linear or branched C1-C30 alkyl or alkenyl radical; said radicals RI and R2 being optionally substituted by a C1-C25 alkoxy, C1-C25 alkyl, nitro, chloro, bromo, cyano, carboxy, ester or mercapto group, • n is an integer ranging from 1 to v + 1 , v being the valence of the element A,

• m is an integer ranging from 0 to v - 1 with n + m = v + 1

Preferably, the anionic entity of the initiator is a borate of formula (IN): [BX _a R _b ] ^" (NI)

in which :

- a and b are integers ranging for a from 0 to 3 and for b from 1 to 4 with a + b = 4, - the symbols X represent:

* a halogen atom (chlorine, fluorine) with a = 0 to 3,

* an OH function with a = 0 to 2,

- the symbols R are identical or different and represent:

> a phenyl radical substituted by at least one electron-withdrawing group such as for example OCF ₃ , CF ₃ , ΝO ₂ , CN, and / or by at least 2 halogen atoms (especially fluorine), and this when the cationic entity is an onium of an element from groups 15 to 17,

> a phenyl radical substituted by at least one element or an electron-withdrawing group, in particular a halogen atom (especially fluorine), CF ₃ , OCF ₃ , NO ₂ , CN, and this when the cationic entity is an organometallic complex of a element from groups 4 to 10

> an aryl radical containing at least two aromatic rings such as for example biphenyl, naphthyl, optionally substituted by at least one element or an electron-withdrawing group, in particular a halogen atom, in particular fluorine, OCF3, CF3, NO2, CN, whatever the cationic entity. The initiator can advantageously be chosen from the group consisting of: [(C ₈ H ₁₇ ) -O-Φ-I-Φ)] ⁺ , [B (C ₆ F ₅ ) ₄ ] -, [(CH ₃ ) ₂ -CH-Φ-I-Φ-CH3] ⁺ , [B (C ₆ F ₅ ) ₄ ] - [(Cι ₂ H ₂₅ -Φ-I-Φ] ⁺ , [B (C ₆ F ₅ ) ₄ ] - [(C ₈ H ₁₇ -O-Φ) ₂ I] ⁺ , [B (C ₆ F ₅ ) ₄ ] -

[(C ₈ Hι ₇ ) -O-Φ-I-Φ)] +, [B (C ₆ F ₅ ) ₄ ] - [(Φ) 3S] ⁺ , [B (C ₆ F ₅ ) ₄ ] ^"

[(Φ) ₂ S-Φ-OC ₈ Hι ₇ ] ⁺ , [B (C ₆ H ₄ CF ₃ ) ₄ ] "[(C ₁₂ H ₂₅ -Φ) ₂ I] +, [B (C ₆ F ₅ ) ₄ ] ^" [(CH ₃ ) ₂ -CH-Φ-I-Φ-CH ₃ ] ⁺ , [B (C ₆ H ₃ (CF ₃ ) ₂ ) ₄ ] - (η ⁵ -cyclopentadiènyle) (η ⁶ - toluene) Fe ⁺ , [B (C6F5) ₄ ] "(η ^D -cyclopentadienyl) (η ⁶ -methyl-l-napthalene) Fe ⁺ , [B (CgF5)] ^" (ï -cyclopentadiènyle) (η ⁶ -cumene) Fe ⁺ , [B (CgF5) ₄ ] "

According to a variant of the invention, the initiator can also be a non-toxic onium salt whose cationic structure is of formula (Nile):

[(CH (CH ₃ ) ₂ -Φ -) - I - (- R ¹ )] ⁺ (Nil) in which the symbol R ¹ represents the radical -Φ-R ² , R ² being a linear or branched alkyl radical comprising from 1 to 20 carbon atoms, preferably 1 to 15 carbon atoms.

The anionic structure of the onium salt is chosen from the group comprising: Cl ^" , B, BF ₄ ^" , PF ₆ \ CF ₃ SO ₃ -, Ν (SO ₂ CF ₃ ) ₂ -, C (SO ₂ SF ₃ ) ₂ ^' , B (C ₆ F ₅ ) -f, B (PhOCF ₃ ) ₄ ^" , SbF <f and / or AsF ₆ ^" . However, the following initiators have been found to be particularly interesting:

[(CH (CH ₃ ) ₂ -Φ -) - I-Φ-CH ₃ ] ⁺ Cl ^" [(CH (CH ₃ ) ₂ -Φ -) - I-Φ-CH ₃ ] ⁺ B (C ₆ F ₅ ) ₄ -

[(CH (CH ₃ ) ₂ -Φ -) - I-Φ-CH ₃ f PF ₆ ^" [(CH (CH ₃ ) ₂ -Φ -) - I-Φ-CH ₃ ] ⁺ B (PhOCF ₃ ) ₄ ^"

[(CH ₃ ) ₂ -CH-Φ-I-Φ-CH ₃ ] +, [B (C ₆ H ₃ (CF ₃ ) ₂ ) ₄ ] "

Such initiators are described in document FR-A-2 762 001.

The silicone oligomer is defined by the following formula (VIII)

Z ⁴ If (R ^υ ) _a O _(3. _{A) / 2} in which:

- a = 0, 1 or 2,

- R °, identical or different, represents an alkyl, cycloalkyl, aryl, vinyl, hydrogen, alkoxy radical, preferably a lower Cι-C ₆ alkyl,

- Z ⁴ is in particular chosen from the following radicals:

- (CH ₂ ) ₃ - 0-CH ^:: CH.

- (CH ₂ ) ₃ O - CH = CH- R "

Even

The silica used can be from different sources: precipitation silica, combustion silica, silica aerogels, silica sol and / or natural silica.

According to a preferred embodiment of the invention, the amorphous silica contained mainly or completely in the silicone phase comes from silica sol and more particularly from silica organosols; a general description of silica soils is given in document US 2,801,185 and "The colloid chemistry of silica and silicates" (Ralph K. Iler, Cornell University Press - 1955, see in particular pages 120-121).

Examples of commercial silica organosols include those from the companies Clariant, Fuso Chemicals, Nalco, Degussa-Huls and Dupont Chemicals.

For Clariant, the following products may be mentioned: Highlink® OG1-32; Highlink® OG8-32; Highlink® OG401-31; Highlink® OG502-30; Highlink® OG502-31 and Highlink® OG600-51. The silica particles have an average diameter of less than 1 μm, and more preferably between 50 and 500 nm.

It should be noted that the colloidal or combustion silica used to reinforce the coating is conveyed in an organic solvent and in particular an alcoholic solvent such as secondary or tertiary primary alcohols. Isopropanol or diacetone alcohol are the solvents of choice.

It is also possible to use ketones, tetrahydrofuran, hydrocarbon fractions or fluorinated solvents.

Preferably, the proportion of organic solvent in the composition according to the invention is at least equal to 10 parts by weight.

Another subject of the invention relates to a process for producing a cationically crosslinkable composition as a hard coating as described above, which essentially comprises the step consisting in mixing particles of colloidal silica which is not functionalized with:

at least one monomer, oligomer and / or crosslinkable and / or polymerizable silicone polymer comprising at least one unit of formula (I) and a total number of silicon atoms per molecule at least equal to 2,

an effective amount of at least one cationic initiator, optionally at least one organic solvent,

- optionally at least one crosslinkable and / or polymerizable silicone monomer, oligomer and / or polymer comprising at least one unit of formula (II), - optionally at least one crosslinkable and / or polymerizable silicone monomer, oligomer and / or polymer comprising at least one unit of formula (III) or a perfluoropolyether compound of the following formula (IN).

Another object of the invention relates to a process for producing a hard coating on a support based on at least one thermoplastic material, characterized in that it comprises the steps consisting in: a) mixing a non-functionalized colloidal silica with:

- an effective amount of at least one cationic initiator,

- optionally at least one organic solvent, - optionally at least one monomer, oligomer and / or crosslinkable and / or polymerizable silicone polymer comprising at least one unit of formula

(II)

- Optionally at least one monomer, oligomer and / or crosslinkable and / or polymerizable silicone polymer comprising at least one unit of formula (III) or a compound; b) applying the mixture obtained on the support based on at least one thermoplastic material, and c) curing the composition by crosslinking into a hard coating by thermal or actinic route.

In order to obtain a thin layer of hard coating of less than 5 microns, it is advantageous to use a volatile organic solvent which is evaporated before irradiation. The solvent is volatilized before irradiation but can also react with the base, in the case of alcohols which react with the oxirane functions during the process, in this case there is a reactive diluent.

Finally, a last object of the invention relates to a hard coating obtained from the composition or by the process according to the invention.

The following examples are given by way of illustration. They allow in particular to better understand the invention and to highlight some of its advantages and illustrate some of its variant embodiments.

EXAMPLE:

The products used in the compositions of the examples are the following:

- the epoxy-functional silicone oligomer of formula (A) containing approximately 5% of

(AT')

the onium borate (PI) initiator:

- Colloidal silicas:

Highlink OG (OG1-32 (ethylene glycol), OG8-32 (pentanediol), OG401-31 (ethylene glycol monopropyl ether), OG502-30 (isopropanol), OG502-31 (isopropanol), OG600-51 (butyl acetate)) marketed by Clariant®

Nanopox from Hanse Chemie like Nanopox XP 22/0314 reinforced with a cycloaliphatic epoxy resin.

- Combustion combustion silicas treated with acrylates such as Aerosil R711 or Aerosil R7200 from Degussa.

Example 1: Preparation of a Flexform 40 thermal control formulation

This solution is sold by the company EXXENE for anti-abrasion coatings. This solution is applied by soaking on a polycarbonate plate at 20 ° C and then dried at 25 ° C for 10 min followed by thermal crosslinking at 122 ° C for 35 min. The thickness of the film is two micrometers. A Taber abrasion resistance test is carried out according to standard T30-015 with a load of 500 g and 300 cycles with CS10-F abrasive wheels. There is a 10% variation in gloss. % Haze = 10% The pencil hardness of the coating varies between 4H and 6H.

Example 2 Preparation of a UN formulation according to the invention without anti-fog 10 g of siloxane resin having a monomer content (A) greater than 90% are loaded into a beaker, obtained by hydrosilylation of 4-vinylcyclohex-1-ene epoxide (NCMX), 1.25 g of photoinitiator system containing 20% of PI photoinitiator dissolved in isopropanol; 40g of highlink colloidal silica in solution in isopropanol at 30%. The system is stable for at least 6 months at room temperature away from light and heat. The solution is applied by soaking on a polycarbonate plate. Leave to drain for a minute.

The system is crosslinked by passing over a UN bench at the speed of 5m / min equipped with two 160W / cm Hg lamps. The system is dry and very hard at the end of the bench. The thickness of the film is 3 micrometers. The pencil hardness is 3 hours immediate and greater than 4 hours after 24 hours. Annealing for 1 hour at 150 ° C or under an InfraRed ramp for a few minutes allows a hardness of 5 hours to be obtained.

The same Taber abrasion test is used and there is a variation in gloss% haze =

15%.

Example 3: Preparation of a UN formulation according to the invention with anti-fog

10 g of siloxane resin having a monomer content (A) greater than 90% are charged into a beaker, 1.25 g of photoinitiator system containing 20% of photoinitiator PI dissolved in isopropanol; 40g of highlink colloidal silica in solution in isopropanol and 0.5 g of polyether silicone Rhodorsil oil 10646.

The system is stable for at least 6 months at room temperature away from light and heat. The solution is applied by soaking on a polycarbonate plate.

Leave to drain for a minute.

The system is crosslinked by passing over a UN bench at the speed of 5 m / min equipped with two lamps of 160 / cm Hg. The system is dry and very hard at the end of the bench.

The film thickness is 3 micrometers

The pencil hardness is 3 hours immediate and greater than 4 hours after 24 hours.

The same Taber abrasion test is used, there is a 10% variation in gloss.

Polycarbonate glass placed in the fridge at 5 ° C does not fog when it comes out of the fridge and placed in an atmosphere at 100% relative humidity and 25 ° C.

Example 4: Preparation of a UN formulation according to the invention with anti-fouling

10 g of siloxane resin having a monomer content (A) greater than 90% are charged into a beaker, 1.25 g of photoinitiator system containing 20% of photoinitiator PI dissolved in isopropanol; 38g of highlink colloidal silica in solution in isopropanol and 2 g of polyfluorosilane tridecafluoro-1,1,2,2 tetrahydrooctyl trimethoxysilane

Leave to drain for a minute. The system is crosslinked by passing over a UN bench at the speed of 5m / min equipped with two 160W / cm Hg lamps. The system is dry and very hard at the end of the bench.

The thickness of the film is 3 micrometers.

However, thermal post-crosslinking is carried out for 1 hour at 100 ° C. to be sure of removing traces of unreacted alkoxy silyl.

The same Taber abrasion test is used, a variation in gloss of 10% is found.

Conventional inks do not mark on the surface of the coating unlike the thermal control based on colloidal silica and alkoxysilanes.

Claims

1. Composition which can be crosslinked cationically with a hard coating, comprising colloidal particles of non-functionalized silica, characterized in that it additionally comprises:

> at least one motif of formula (I):

^Z ( ^R ) aS ^Î O (3-a) / 2 m in which:

- a = 0, 1 or 2,

R °, identical or different when al, represents an alkyl, cycloalkyl, aryl, vinyl, hydrogen, alkoxy radical, preferably a lower C 1 -C ₆ alkyl,

- Z ¹ , identical or different when the number of units of formula (I) is greater than 1, is an organic substituent comprising at least one reactive epoxy, and / or alkenylether and / or oxetane and / or dioxolane and / or carbonate function , and preferably Z ¹ being an organic substituent comprising at least one reactive epoxy and / or dioxolane function,

> and a total number of silicon atoms per molecule at least equal to 2, and an effective amount of at least one cationic initiator, optionally at least one organic solvent.

2. Composition according to claim 1, characterized in that it further comprises, as anti-fogging compound, at least one monomer, oligomer and / or crosslinkable and / or polymerizable silicone polymer comprising at least one unit of formula (II) :

Z (R) aS ^Î O (3-a) / 2 m \ in which:

- a = 0, 1 or 2,

- R ° is as defined above,

- Z ² , identical or different when the number of units of formula (II) is greater than 1, is an organic substituent comprising at least one oxyalkyl or polyoxyalkyl function ((CH ₂ ) _m O) _x or (CH ₂ -CH ( CH ₃ ) -O) _y or copolymers, said monomer, oligomer and / or polymer having a viscosity of less than 500 mPa-s ^"1 and preferably less than 300 mPa.s ^_1 .

3. Composition according to one of claims 1 or 2, characterized in that it also comprises, as anti-fouling compound, at least one monomer, oligomer and / or crosslinkable silicone polymer and / or polymerizable comprising at least one unit of formula (III):

in which :

- a = 0, 1 or 2,

- Z, identical or different when the number of units of formula (III) is greater than 1, is an organic substituent comprising at least group

(C _n F _{2n + 1} ) - (R °) _a with n <20 and / or a perfluoropolyether compound of formula (IN):

Y- (C _a F _2a O) _b -C _a F _2a -Y (IN)

in which :

- Y is a polymerizable group,

- a is between 1 and 7,

4. Composition according to one of the preceding claims, characterized in that the cationic initiator is chosen from those whose cationic entity is selected from onium salts of formula (N):

in which :

• A represents an element from groups 15 to 17 such as for example: I, S, Se, P orΝ, R ¹ represents a C 6 -C 20 carbocyclic or heterocyclic aryl radical, said heterocyclic radical possibly containing nitrogen or sulfur as heteroelements,

• R ² represents RI or a linear or branched C1-C30 alkyl or alkenyl radical; said radicals RI and R2 being optionally substituted by a C1-C25 alkoxy, C1-C25 alkyl, nitro, chloro, bromo, cyano, carboxy, ester or mercapto group,

• n is an integer ranging from 1 to v + 1, v being the valence of the element A, • m is an integer ranging from 0 to v - 1 with n + m = v + 1,

5. Composition according to the preceding claim, characterized in that the anionic entity of the initiator is a borate of formula (NI):

[BX _a R _b ] ^" (NI)

in which :

* a halogen atom (chlorine, fluorine) with a = 0 to 3,

* an OH function with a = 0 to 2,

- the symbols R are identical or different and represent:

> an aryl radical containing at least two aromatic rings such as for example biphenyl, naphthyl, optionally substituted by at least one element or an electron-withdrawing group, in particular a halogen atom, in particular fluorine, OCF3, CF3, NO2, CN, whatever the cationic entity.

6. Composition according to any one of the preceding claims, characterized in that the initiator is chosen from the group consisting of: [(C ₈ H ₁₇ ) -O-Φ-I-Φ)] +, [B (C ₆ F ₅ ) ₄ ] -, [(CH ₃ ) ₂ -CH-Φ-I-Φ-CH ₃ ] +, [B (C ₆ F ₅ ) ₄ ] -

[(Cι ₂ H ₂₅ -Φ-I-Φ] +, [B (C ₆ F ₅ ) ₄ ] - [(C ₈ Hι ₇ -O-Φ) ₂ I] +, [B (C ₆ F ₅ ) ₄ ] ^" [(C ₈ Hι ₇ ) -O-Φ-I-Φ)] +, [B (C ₆ F ₅ ) ₄ ] - [(Φ) ₃ S] +, [B (C ₆ F ₅ ) ₄ ] -

[(Φ) ₂ S-Φ-OC ₈ Hι ₇ ] +, [B (C ₆ H ₄ CF ₃ ) ₄ ] - [(C ₁₂ H ₂₅ -Φ) ₂ I] +, [B (C ₆ F ₅ ) ₄ ] - [(CH ₃ ) ₂ -CH-Φ-I-Φ-CH] +, [B (C ₆ H ₃ (CF ₃ ) ₂ ) ₄ ] - (η ⁵ -cyclopentadienyl) (η ⁶ -toluene ) Fe ⁺ , [(C Fζ) 4] '(η ⁵ -cyclopentadiènyle) (η ⁶ -methyl-l-napthalene) Fe ⁺ , [B (CgF5) ₄ ] ~ (η ⁵ -cyclopentadiènyle) (η ⁶ -cumène ) Fe ⁺ , [B (C6F5)] ^~

7. Composition according to one of the preceding claims, characterized in that the cationic initiator a non-toxic onium salt whose cationic structure is of formula (VII):

[(CH (CH ₃ ) ₂ -Φ -) - I - (- R ¹ )] ⁺ (Nil)

in which R ¹ represents the radical -Φ-R ² , R ² being a linear or branched alkyl radical comprising from 1 to 20 carbon atoms, preferably 1 to 15 carbon atoms.

8. Composition according to the preceding claim, characterized in that the anionic structure of the onium salt is chosen from the group comprising: Cl ^" , Br ^' , BF ^" , PF ₆ ^" , CF ₃ SO ₃ ^" , Ν (SO ₂ CF ₃ ) ₂ -, C (SO ₂ SF ₃ ) ₂ ^" , B (C ₆ F ₅ ) ₄ \ B (PhOCF ₃ ) ₄ ^" , SbF <f and / or AsF ₆ ^" .

9. Composition according to one of the preceding claims, characterized in that the silicone oligomer is defined by formula (VIII):

^z If (R) _a O ₍₃ _ _{a) 2} in which:

- a = 0, 1 or 2,

- R °, identical or different, represents an alkyl, cycloalkyl, aryl, vinyl, hydrogen, alkoxy radical, preferably a lower Cι-C ₆ alkyl, - Z ⁴ is especially chosen from the following radicals:

O ^' ^

O

- (CH ₂ ) ₃ - O - CH ^ CH,

- (CH,) ₃ O - CH = CH - R "

10

Even

10. Composition according to one of claims 3 to 9, characterized in that the perfluoropolyether compound is taken from the group comprising: (C ₂ H ₅ O) ₂ CH ₃ SiC3H ₆ NHCO (CF ₂ O) ₁₅ (C ₂ F ₄ O) ₁₃ CF ₂ CONHC ₃ H ₆ SiCH ₃ (OC ₂ H5) 2, (C ₂ H ₅ O) ₃ SiC ₃ H ₆ NHCO (CF ₂ O) i5 (C ₂ F ₄ O) ₁₃ CF ₂ CONHC ₃ H ₆ Si (OC ₂ H ₅ ) ₃ , F (CF (CF ₃ ) CF ₂ O) ₂₅ CF ₂ CF3, C ₄ H ₉ NHCO (CF ₂ O) i ₅ (C ₂ F ₄ O) ₁₃ CF ₂ CONHC ₄ Hg, CH ₂ = CHCOOC ₂ H ₄ NHCO (CF ₂ θ) i ₅ (C ₂ F ₄ O) i ₃ CF ₂ CONHC ₂ H ₄ OOCCH = CH ₂ ,

CH2 = CHCOOCH2 (CF ₂ O) ι ₅ (C2F ₄ O) ₁₃ CF2CH2θOCCH = CH2, (HOCH2) ₂ CH ₂ NHCO (CF ₂ O) ι ₅ (C ₂ F ₄ O) ι ₃ CF ₂ CONHCH ₂ (CH ₂ OH) ₂ , (C ₂ H ₅ O) ₃ Si (CH ₂ ) ₃ NHCO (CF ₂ CF ₂ O) ₈ CF ₂ CONH (CH ₂ ) ₃ Si (OC ₂ H ₅ ) ₃ , (C ₂ H ₅ O ) ₂ CH ₃ Si (CH ₂ ) ₃ NHCO (CF ₂ CF ₂ O) ₈ CF ₂ CONH (CH ₂ ) ₃ SiCH ₃ (OC ₂ H ₅ ) ₂ , (C ₂ H ₅ O) ₂ CH ₃ Si (CH ₂ ) ₃ NHCO (CF ₂ CF ₂ O) ₁₄ CF2CONH (CH ₂ ) ₃ SiCH ₃ (OC ₂ H ₅ ) ₂ ,

(C2H ₅ O) 3Si (CH ₂ ) 3NHCO (CF2C (CF3) FO) ₁₂ CF ₂ CONH (CH ₂ ) 3Si (OC2H5) 3, (C ₂ H ₅ O) ₂ CH ₃ Si (CH ₂ ) ₃ NHCO (CF ₂ C (CF ₃ ) FO), ₂ CF ₂ CONH (CH ₂ ) ₃ SiCH ₃ (OC ₂ H ₅ ) ₂ θu OOCCH = CH ₂ OOCCH = CH ₂

H ₂ C = HCCOO-CH ₂ CHCH ₂ NHCO (CF ₂ 0) _I5 (CF ₂ CF ₂ θ) ₁₃ CF ₂ CONHCH ₂ CHCH ₂ -OOCCH = CH ₂ .

11. Composition according to one of the preceding claims, characterized in that the silica particles have an average diameter of less than 1 μm, and more preferably between 50 and 500 nm.

12. Composition according to one of the preceding claims, characterized in that the organic solvent is an alcoholic solvent.

13. Composition according to one of the preceding claims, characterized in that the proportion of organic solvent is at least equal to 10 parts by weight.

14. Method for producing a cationically crosslinkable composition in hard coating according to one of claims 1 to 13, characterized in that it essentially comprises the step consisting in mixing colloidal particles of non-functionalized silica with: at least one crosslinkable and / or polymerizable silicone monomer, oligomer and / or polymer comprising at least one unit of formula (I) and a total number of silicon atoms per molecule at least equal to 2,

- an effective amount of at least one cationic initiator, - optionally at least one organic solvent,

- optionally at least one crosslinkable and / or polymerizable silicone monomer, oligomer and / or polymer comprising at least one unit of formula (II), optionally at least one crosslinkable and / or polymerizable silicone monomer, oligomer and / or polymer comprising at least one unit of formula (III) or a perfluoropolyether compound of the following formula (IV).

15. Method for producing a hard coating on a support based on at least one thermoplastic material, characterized in that it comprises the steps consisting in: a) mixing a non-functionalized colloidal silica with: - at least one monomer , crosslinkable and / or polymerizable silicone oligomer and / or polymer comprising at least one unit of formula (I) and a total number of silicon atoms per molecule at least equal to 2, - an effective amount of at least one cationic initiator , optionally at least one organic solvent, - optionally at least one monomer, oligomer and / or crosslinkable and / or polymerizable silicone polymer comprising at least one unit of formula

(II), optionally at least one monomer, oligomer and / or crosslinkable and / or polymerizable silicone polymer comprising at least one unit of formula (III) or a compound; b) applying the mixture obtained on the support based on at least one thermoplastic material, and c) curing the composition by crosslinking into a hard coating by thermal or actinic route.

16. Hard coating obtained from the composition according to one of claims 1 to 13 or by the process according to claim 15.