EP1458828A1

EP1458828A1 - Liquid silicone formulation for producing release and water-repellent crosslinked elastomer coatings on a solid support, such as a paper support

Info

Publication number: EP1458828A1
Application number: EP02793185A
Authority: EP
Inventors: Jean-Paul Benayoun; Didier Dhaler; Jacques Kieffer; Frédéric MAGD; John White
Original assignee: Rhodia Chimie SAS
Current assignee: Rhodia Chimie SAS
Priority date: 2001-10-26
Filing date: 2002-10-24
Publication date: 2004-09-22
Also published as: FR2831547B1; WO2003035781A1; BR0213759A; JP2005506437A; US20050053793A1; FR2831547A1

Abstract

The invention concerns a liquid silicone formulation for producing release and water-repellent crosslinked elastomer coatings on a solid support, such as a paper support. The invention aims at solving the adherence defect of elastomer silicone films with release outer surface designed to be glued on soft supports such as closed paper, for example glassine or polypropylene polymer films. Therefor, the inventive liquid silicone formulation, for use as a coating base for high-speed production of crosslinked release and water repellent elastomer coating on a solid support, comprises at least a crosslinkable polyorganosiloxane POS (I), (SiVi-type POS and SiH-type POS); at least a (platinum-based) catalyst (ii); optionally an adherence modulator system (III); an adherence promoter (IV) comprising an epoxidized alkoxysilane and/or an alkenylated alkoxysilane, as well as a metal chelate and/or a metal alkoxide (GLYMO/MEMO/TiO4Bu). The POS (I) the most viscous has a viscosity less than 1000 mPa's. The invention is for paper release coating.

Description

Liquid silicone formulation for the production of crosslinked non-stick and water-repellent elastomeric coatings on solid support, for example paper

The field of the invention is that of non-stick and water-repellent coatings for flexible supports, for example paper or polymer film. The non-stick coatings considered are more particularly those based on silicone elastomer crosslinked in situ, that is to say after coating on solid supports, for example in paper or in polymer film, of non-crosslinked liquid silicone formulations.

In particular, the non-stick silicone coatings referred to in this presentation are those comprising one or more polyorganosiloxane (POS) crosslinkable by polyaddition (POS Si-H / POS Si-Ninyle), by polycondensation, by cationic or radical polymerization , under thermal and / or actinic activation and / or using an electron beam.

In these non-stick applications, for example on paper or on polymer film, the liquid silicone coating formulations contain, in addition to the silicone polymers, a polycondensation or polyaddition catalyst or a cationic or radical initiator, as well as at least one system. adhesion modulator, for example based on silicone resin comprising siloxy units Q: (SiO _4/2 ) and / or T: (RSiO _3/2 ). These liquid silicone formulations are applied to the support films in industrial coating devices comprising cylinders operating at very high speed (600 m / min).

Naturally, it is clear that in these very high speed coating procedures the viscosity of the liquid silicone coating formulation must be carefully adapted to the coating operating conditions.

In these liquid silicone coating formulations, the silicone phase can be diluted in a solvent. According to a more advantageous variant, in particular for health and safety reasons, the liquid silicone formulation is an aqueous dispersion / emulsion. Once applied to the support film, the silicone formulation crosslinks to form a solid coating of non-stick and / or water-repellent silicone elastomer. Given the industrial rates of coating at very high speed, the crosslinking kinetics must be instantaneous.

If the primary function of such a silicone coating is the anti-adhesion of its external face, the fact remains that the coating must be fixed, by its internal face, on the flexible solid support, with very strong adhesion. The anti-adhesion of the external face of the silicone coating is expressed through the release force, which must be low and controlled, for the element intended to be placed on the support coated with the non-stick silicone film. Conventionally, this element can be the adhesive side of a label or a ribbon of the same name. Thus, in addition to this weak and controlled anti-adhesion, the adhesion of the silicone coating on its support must be very high. This adhesion property can be assessed, for example, using the "rub off" trade test, which consists of rubbing the surface of the coating with a finger and measuring the number of successive passes which lead to degradation of the coating. The solid supports coated with a non-stick silicone film can be for example:

- an adhesive tape, the internal face of which is coated with a layer of pressure-sensitive adhesive and the external face of which comprises the non-stick silicone coating;

- or a paper or a polymer film for protecting the adhesive face of a pressure-sensitive adhesive or adhesive element, this element being able to be made of paper or polymer film of polyvinyl chloride (PNC), PolyEster, PolyPropylene type, or

PolyEthyleneTerephthalate, the non-adhesive side of this element being generally printed or printable so as to be able to serve as a label capable of being detached from its support and glued by simple pressure on an article to be identified. In practice, the deposition rate of non-stick silicone is between 0.1 and

1 preferably 0.3 and 0.5 g / m ² , which corresponds to thicknesses of the order of a micrometer.

However, in the state of the art, it is known that on certain supports such as very closed papers such as glassine or such as PE polymer films in PP, for example, the adhesion characteristics of crosslinked silicone films are poor (few successive passes to the "rub off." test)

These poor adhesion characteristics are further amplified when the coating / crosslinking rates of the liquid silicone formulation increase. Glassine-type papers with a grammage equal to 60-65 g / m ² are papers made from a highly refined bisulfite pulp which leads to significant entanglement of the fibers and which contributes to "closing" the paper. The two phases of glassine paper are coated with a layer based on polyvinyl alcohol and carboxymethyl cellulose. The paper is then calendered to give it a certain transparency.

Various prior technical proposals have emerged to try to solve this problem of the adhesion of a silicone coating having an external non-stick face, on supports such as very closed papers such as glassine or polymer films such as polyester or polypropylene. Thus, a DOW CORNING / DOW CORNLNG-TORAY patent dating from 1971 (US-B-3 691 206) discloses the use of a mixture of acetoxysilane and 3-GLYcydoxypropyltriMethOxysilane (GLYMO) to improve the adhesion on supports by paper of elastomeric silicone coatings crosslinking by condensation. The adhesion performance obtained using this acetoxysilane + GLYMO promoter remains entirely perfectible.

European patent EP-B-0 272 809 relates to an adhesion promoter intended to be incorporated in POS compositions crosslinkable by radical route under actinic activation (UN) or by exposure to an electron beam. This adhesion promoter is based on a mixture of alkoxylated silane such as for example: vinyltrimethoxysilane / Ν-β- (aminoethyl) -γ-aminopropyl-trimethoxysilane. It is in fact a co-hydrolisal of these 2 alkoxysilanes which condense to form copolymers. Such an adhesion promoter is added to a silicone composition based on POS crosslinkable by the radical route under a UN or under an electron beam (polydimethylsiloxane / γ-mercaptopropylmethylsiloxane copolymer with trimethylsiloxy ends), in a proportion of 0.1 to 30 parts in promoter weight per 100 parts by weight of POS. It is shown in the examples of this European patent that the promoter claimed based on the vinyltrimethoxysilane / Ν-β- (aminoethyl) -γ-aminopropyl-trimethoxysilane mixture gives better results in tarnished adhesion ("rub off") than the compounds of the mixture taken separately, however, this patent does not demonstrate significant improvement in adhesion properties.

French patent application FR-A-2 469 435 discloses adhesion promoters based on alkoxysilane (methyltrimethoxysilane / γ- (aminoethyl) -aminopropyl-trimethoxysilane) in admixture with a dibutyltin diacetate catalyst. Such an adhesion promoter is associated with POS compositions carrying OH and / or OR groups crosslinkable by polycondensation. This adhesion promoter does not appear to be particularly effective.

Furthermore, in a field other than that of paper anti-adhesion, the French invention patent FR-B-2 719 598 discloses silicone elastomeric coating compositions of EVF type that can be cold cured, comprising at least one POS Si-Ni, at least one POS and Si-H, a platinum catalyst, an adhesion promoter, optionally a mineral filler, optionally a crosslinking inhibitor and optionally a POS resin. The adhesion promoter includes:

- vinyltrimethoxysilane (NTMS), - 3-GLYcydoxypropyltriMethOxysilane (GLYMO),

- and butyl titanate. In these silicone compositions crosslinkable at room temperature by polyaddition, the silicone phase has an overall dynamic viscosity at 25 ° C. greater than 3000 mPa.s. In practice, the Si-Ni oils used have a viscosity of 100,000 mPa.s and 10,000 mPa.s respectively, while the viscosity of POS Si-H oil is of the order of 300 mPa. s.

Furthermore, these silicone compositions crosslinkable at room temperature by polyaddition, are intended to be applied to supports which are preferably fibrous and more preferably still to textile supports made of synthetic fibers of the polyester or polyamide type. A common use of these crosslinkable silicone compositions is the coating of air bags intended for the protection of an occupant of a vehicle ("air bag").

Given its very high viscosity, the silicone composition according to FR-B-2 719 598 cannot really be considered as completely liquid.

In addition, the adhesion promoter which it comprises necessarily comprises 3 constituents: alkoxylated and alkenylated silane (vinyltrimethoxysilane) / alkoxylated and epoxidized silane (GLYMO) / metal chelate (butyl titanate).

It should also be noted that in applications of silicone elastomer coating on textiles for mechanical reinforcement purposes, the industrial coating rates have nothing comparable with the coating speeds of non-stick silicone coating on paper or polymer film supports: 10-20 m / min versus 600 m / min. In the same way, the thickness of the films deposited in these two applications is completely different: 20-30 μm versus 1 μm.

In fact, in textile coating applications, silicone compositions are used comprising long silicone oils of high viscosity, while in liquid silicone formulations for non-stick coating of paper or polymer film, the POSs used are short POSs of low viscosity.

European patent application EP-A-0 771 901 is another illustration of the use of a polyorganosiloxane composition for coating a textile support, in this case coated with a silicone elastomer material. This textile support coated with a silicone multilayer is in this case constituted by a conveyor belt, usable in particular for food contact. The silicone composition used is a viscous composition loaded with silica and comprising an α, ω-divinylated polydimethylsiloxane oil, with a maximum viscosity equal to 1000 mPa.s, a charge of aluminum hydroxide, a Karstedt platinum catalyst, a PolyDiMethylSiloxane α, ω-hydrogen oil with a viscosity of 40 mPa.s, another PDMS oil with ≡SiH units with a viscosity of 30 mPa.s, as well as a crosslinking inhibitor of the ethynylcyclohexanol type. It is clear that this is a viscous coating composition for textile support, said coating being carried out without scrolling of the support or with scrolling at very low speed. In addition, the overall dynamic viscosity of this composition is much greater than 1000 mPa.s. As a result, the silicone coating composition according to EP-A-0 771 901 does not solve the problem of producing, at very high running speed, a crosslinked elastomeric coating which is non-stick and water-repellent, on a solid support, with very strong adhesion.

There are also liquid silicone formulations on the market for coating anti-adhesion on paper support or polymer film containing adhesion promoters based on vinyl acetoxysilane (Vi-Si (OCH ₃ ) ₃ ) and GLYMO. However, such promoters are not satisfactory in terms of the adhesion of non-stick silicone films to particular supports of the closed paper type (glassine) or polymer film of the polypropylene type.

It is therefore clear that the previous technical proposals do not provide satisfactory solutions to the problem of the lack of adhesion of elastomeric silicone films whose external face is non-adherent and which are intended to be bonded to flexible supports of the paper type. closed type glassine or polymer film type polypropylene.

One of the essential objectives of the present invention is to provide a liquid silicone formulation which can be used as a coating base for producing - at very high speed - a non-stick, water-repellent cross-linking elastomer coating on a solid support, said formulation allowing a excellent adhesion of the coating to the support, while having all the anti-adhesion and / or hydrophobicity characteristics as well as all the desired mechanical qualities.

Another essential objective of the present invention is to provide a non-crosslinked liquid silicone formulation having rheological characteristics such that they can be easily applied to the surface of a support film circulating at very high speed, said formulation once coated then being able to crosslink to form a hardened coating firmly attached to the support by one of its faces and the other face of which has non-stick and / or water-repellent properties, as well as optimal mechanical qualities.

Another essential objective of the invention is to provide a liquid silicone formulation which can be used as a coating base for the production at very high speed of crosslinked non-stick elastomeric coatings on a solid support of very closed paper type (glassine) or of polyester or polypropylene film, said coating being perfectly bonded to the support. Another essential objective of the present invention is to propose a process for producing at high speed a crosslinked elastomeric coating which is non-stick and water-repellent on a solid support, a process in which:

"first of all, a pre-coating based on a functionalized POS is grafted on with patterns which only wish to saturate, for example of the type

(meth) acrylate, said patterns to be saturated being intended to allow polymerization of the graft functionalized POS; "and an outer layer based on a non-stick silicone elastomer perfectly attached to the pre-coating based on functionalized grafted and polymerized POS is coated.

Another essential objective of the invention is to provide a solid support, for example in closed paper of the glassine type or in a polymer film of the polypropylene or polyester type, on which would be securely attached to a non-stick and / or water-repellent crosslinked silicone elastomer coating. . These objectives, among others, are achieved by the present invention which firstly relates to a liquid silicone formulation, usable as a coating base for the production - at very high speed - of crosslinked elastomeric coatings which are non-stick and water-repellent on a support. solid, this formulation comprising in particular: at least one silicone composition based on at least one polyorganosiloxane (I) crosslinkable by polyaddition, by polycondensation, by cationic or radical route, under thermal and / or actinic activation and / or obtained with using an electron beam,> - at least one catalyst / initiator (II), - optionally, at least one adhesion modulator system (III), characterized:

- in that it also comprises at least one adhesion promoter (IN) based on:

• at least one of the following compounds (IN.l) and (IN.2): o (IN.1) at least one alkoxysilane comprising at least one epoxy radical, o (IN.2) at least one alkoxysilane containing, per molecule , at least one C2-C6 alkenyl group,

• and in addition: o (IN.3) at least one metal chelate M and / or a metal alkoxide of general formula M (OJ) _n , with n = valence of M and J = linear or branched C \ - alkyl Cg.

M being chosen from the group formed by: Ti, Zr, Ge, Li, Mn, Fe, Al,

Mg; - And in that the POS (I) of higher viscosity has (have) a dynamic viscosity η at 25 ° C less than 1000 mPa.s, preferably less than 900 mPa.s, and more preferably still less than 800mPa.s,

- and in that its overall dynamic viscosity is less than or equal to 1000 mPa.s.

By using this specific adhesion promoter (IN) in this low viscosity liquid silicone formulation, the invention makes it possible to access high levels of adhesion of the non-stick silicone elastomer coating crosslinked on various supports. In particular, it is possible thanks to the invention to adhere a crosslinked elastomeric silicone coating which is non-stick and / or water-repellent on supports known to be difficult, such as, for example, polyethylene terephthalate PET films, PE polyethylene films or polypropylene PP films. , as well as tightly closed papers such as glassines.

The formulation according to the invention has the singularity that it is liquid, that is to say that it has sufficiently low viscosity characteristics, so that its application on solid supports circulating at very high speed, is easily achievable. In practice, this corresponds to an overall dynamic viscosity at 25 ° C less than or equal to 1000 mPa.s. This rheological characteristic of the liquid silicone formulation is partly due to the fact that the POS (s) (s) more viscous, has (have) a dynamic viscosity η at 25 ° C less than 1000 mPa.s, preferably less than 900 mPa.s, and more preferably still less than 800mPa.s.

Such a low viscosity liquid character makes it possible to achieve very thin coating thicknesses on the order of a micrometer.

It is to the credit of the inventors to have found that, quite surprisingly and unexpectedly, the association of an epoxidized alkoxysilane or of an alkenylated alkoxysilane with a chelate and / or a metal alkoxide leads to a completely significant grip.

Without being limiting, the term “very high speed” of travel of the support to be coated corresponds, in accordance with the invention, to a speed, for example, greater than or equal to: 40 m / min, preferably 60 m / min, and more preferably still at 70 m / min, and better still at 500 m min. To further enhance the beneficial effect of the adhesion promoter according to the invention, it is advantageous to use a Corona treatment on the supports intended to receive the crosslinked elastomer coating resulting from the formulation according to the invention. This Corona treatment is particularly recommended for polymeric supports. The Corona treatment consists in degrading the surface of the support by an electric discharge and creating reactive functions which will promote attachment.

According to a preferred characteristic of the invention, the epoxidized alkoxysilane (IN.l.) of the promoter (IN) is chosen:

- or among the epoxidized alkoxysilanes (IN. la) of the following general formula:

in which :

R ¹ is a linear or branched al yl radical in Cι-C, R ² is a linear or branched alkyl radical y is equal to 0, 1, 2 or 3,

with

Δ E and D which are identical or different radicals chosen from linear or branched Cι-C ₄ alkyls, Δ z which is equal to 0 or 1,

Δ R ³ , R ⁴ , R ⁵ which are identical or different radicals representing hydrogen or a linear or branched C1-C4 alkyl, Δ R ³ and R ⁴ or R ⁵ can alternately constitute together with the two carbons carrying epoxy, an alkyl ring having from 5 to 7 members, - either from epoxidized alkoxysilanes (IN.lb) constituted by epoxyfunctional polydiorganosiloxanes comprising at least one unit of formula:

X _p G _q SiO ₄ . _{(p + q) / 2} (IN. lbi) in which :

X is the radical as defined above for the formula (IN.1 a)

G is a monovalent hydrocarbon group, free from any adverse action on the activity of the catalyst and chosen from alkyl groups having from 1 to 8 carbon atoms included, optionally substituted by at least one halogen atom, and also from aryl groups, p = 1 or 2, q = 0, 1 or 2, - p + q = 1, 2 or 3. optionally at least some of the other units of these polydiorganosiloxanes are units of average formula:

G ' _r SiO ₄ - _{r / 2} (IN.lbii)

in which G 'has the same meaning as that of G' given above and r has a value between 0 and 3.

These IN.l compounds are therefore preferably epoxidized alkoxysilanes comprising only one silicon atom.

As regards the alkenylated alkoxysilanes (IN.2), the ones corresponding to the following general formula (IN.2) are preferably chosen to enter into the constitution of the adhesion promoter according to the invention:

(IN.2)

in which :

- R ⁶ , R ⁷ , R ⁸ are hydrogenated or hydrocarbon radicals identical or different from each other and representing hydrogen, a linear branched C alkyl _. -C ₄ or a phenyl optionally substituted by at least one Cι-C ₃ alkyl,

- A is a linear or branched C1-C4 alkylene, or a divalent group of formula -CO-O-alkylene - * -, where the alkylene residue is as defined above and the valence - is linked to Si via G , - G is a valence link,

- R and R are identical or different radicals and represent a linear or branched C1-C4 alkyl,

- x '≈ O or l, - x = 0 to 2.

As regards the compound (IN.3), it can consist of, or include, a metal chelate. The metal M chosen may comprise one or more ligands such as those derived, in particular from a β-diketone, such as for example acetylacetone. The compound (IN.3) may also consist of or comprise a metal alkoxide having the formula M (OJ) n defined above where the alkoxy radicals are for example the n-propoxy and n-butoxy radicals. Note that, in this formula, one or more alkoxy OJ radicals can be replaced by one or more ligands constituting a chelate, such as for example an acetylacetone ligand. The preferred compounds (IN.3) are those in which the metal M is chosen from the following list: Ti, Zr, Ge, Li, Mn, Fe, Al, Mg.

It will be noted that titanium is more particularly preferred, and more especially still titanium tetrabutanolate or butyl titanate: ti (OBu) ₄ .

Concrete examples of compounds (IN.3) which are very suitable are those in the structure of which the metal M is chosen from the list: Ti, Zr, Ge, Li, Mn, Fe, Al, Mg and is associated: as regards from a chelate to ligands of acetylacetonate type, being an alkoxide to n-propoxy or n-butoxy radicals.

According to a preferred embodiment of the adhesion promoter according to the invention, the composition chosen is as follows:

- (IV.1) 3-Glycidoxypropyltrimethoxysilane (GLYMO) and / or 3-glycidoxypropylethoxysilane, and / or β- (3,4-epoxycyclohexyι) - ethyltriethoxysilane, - (IN.2) or vinyltrimethoxysilane (NTMO) and / or 3-methacryloxypropyltrimethoxysilane (MEMO),

- (IN.3) and butyl titanate.

From a quantitative point of view, it should be noted that the weight ratio (IN.l) or (IN-2) / (IN.3) which is used according to the invention, is between 5 and 0.5, and preferably is of the order of 1. Still quantitatively, it can be specified that the adhesion promoter (IN) is present at a rate of 0.1 to 10% by weight, relative to all of the constituents.

In the liquid silicone formulations according to the invention, it is advantageous to use at least one adhesion modulating system (111), to allow the control of the anti-adhesion properties of the crosslinked silicone coating. As an illustration of an adhesion modulator system in silicone formulations for paper or adhesive non-sticking having a polymer support, mention may be made of European patent application EP-A-0 601 938, the content of which is fully included. in this talk.

According to a variant, the adhesion modulator system (III) can be based on:

• (A) at least one polyorganosiloxane resin in solid form in the dry state, and consisting of at least two different types of siloxy units R ₃ SiOι _{/ 2} (unit M) and SiO ₂ (unit Q) and / or RSiO ₃₂ (unit T), and optionally of units R SiO (unit D), the radicals R being identical or different and representing organic radicals, with a ratio number of units (M) / number of units (Q) and / or (T) of 0.6-1, the number of possible units (D) being 0.5-10 per 100 moles of resin;

• (B) and at least one solvent or at least one diluent for the resin (A) or a mixture of resins (A).

The radicals R mentioned above represent linear or branched alkyl radicals in Cι-C ₆ , cycloalkenyls in C ₅ ~ Cι ₂ and / or phenyl.

It should be understood that in the abovementioned resins, part of the radicals R are functional groups which are: a in the case of the formulations which crosslink by polyaddition:

(i) alkenyl groups which are identical or different from one another in C -Cι ₂ , alkenyl (C ₃ -C) or oxyalkylene (C ₂ -C ₄ ); (2i) hydrogen atoms linked directly to Si; (3i) and / or hydroxyl groups linked directly to Si; these aforementioned resins comprising at least 0.1 mol%, preferably from 0.5 to

5 mol% of the functional groups (i), (2i) and or (3i); a in the case of formulations crosslinking by polycondensation:

- groups (3i) a in the case of crosslinking formulations under radiation: - groups (2i) and / or (4i), epoxy groups of formula: with

Δ E and D which are identical or different radicals chosen from linear or branched C ₁ -C ₄ alkyls, Δ z which is equal to 0 or 1,

Δ R, R, R which are identical or different radicals representing hydrogen or a linear or branched Cι-C alkyl, Δ R ³ and R ⁴ or R ⁵ can alternately constitute together with the two carbons carrying the epoxy , an alkyl ring having from 5 to 7 members.

As an example of resins, mention may be made of resins MQ, MDQ, MDT, MDTQ where the functions (i) to (4i) can be carried by the units M, D and / or T. In practice, the resins which are well suited are : crosslinking formulations by polyaddition: MD ^Vi Q MM ^Vi Q MM ^Vi D ^Vi Q MM ^Vi DD ^vi Q

MD ^H Q MM ^H Q crosslinking formulations by polycondensation: M ^0H Q

crosslinking formulations under radiation: MD ^H Q MM ^H Q

Although the invention is not limited to silicone formulations comprising POSs which can be crosslinked by polyaddition, the silicone composition is preferably a mixture formed from:

(1.1) at least one polyorganosiloxane having, per molecule, at least two C ₂ -C ₆ alkenyl groups bonded to silicon, (1.2) at least one polyorganosiloxane having, per molecule, at least three hydrogen atoms bonded to silicon, 1.1 and 1.2, the catalyst II being composed of at least one metal belonging to the platinum group, this composition and this catalyst ( II) being associated with a possible crosslinking inhibitor (V).

Even more preferably:

"the polyorganosiloxane (1.1) has units of formula:

T _a Z_ SiO ₄ _ _{(a + b) / 2} (1.1 i) in which:

- T is an alkenyl group,

- Z is a monovalent hydrocarbon group, free from any unfavorable action on the activity of the catalyst and chosen from alkyl groups having from 1 to 8 carbon atoms included, optionally substituted by at least one halogen atom, and also paπni aryl groups,

- a is 1 or 2, b is 0, 1 or 2 and a + b is between 1 and 3,

- optionally at least some of the other motifs are motifs of medium formula:

Z _c SiO ₄ . _{c / 2} (I.2ii) in which Z has the same meaning as above and ca a value between 0 and 3.

"the polyorganosiloxane (1.2) comprises siloxyl units of formula:

Hd L _e SiO ₄ . _{(d + e) / 2} (I.2i) in which: - L is a monovalent hydrocarbon group, free from any adverse action on the activity of the catalyst and chosen from alkyl groups having from 1 to 8 carbon atoms inclusive, optionally substituted with at least one halogen atom, and also among the aryl groups,

- d is 1 or 2, e is 0, 1 or 2, d + e has a value between 1 and 3, - possibly, at least part of the other units being units of average formula:

Lg SiO ₄ . _{g / 2} (I.2ii) where L has the same meaning as above and g has a value between 0 and 3.

Advantageously, the proportions of (1.1) and of (1.2) are such that the molar ratio of the hydrogen atoms bonded to silicon in (1.2) to the alkenyl radicals bonded to silicon in (1.1) is between 0.4 and 10.

Crosslinking inhibitors (N) which can be used are for example alpha acetylenic alcohols or maleates-fumarates.

According to a variant of the invention, the formulation may comprise one or more conventional additives in the field of silicone non-stick coatings for solid support, for example made of paper. They may, for example, be anti-misting additives: silica particles, e.g.

Although the formulation according to the invention may be an organic solution, it is preferable that it is in the form of an aqueous emulsion / dispersion. The conventional additives of such emulsions / dispersions can be used. Thus, among the emulsifying agents which can be used, alone or as a mixture, mention may be made of conventional anionic agents such as fatty acid salts, alkyl sulfates, alkyl sulfonates, alkyl aryl sulfonates, sulfosuccinates, alkyl phosphates of alkali metals, the salts of abietic acid, hydrogenated or not, nonionic agents such as polyethoxylated fatty alcohols, polyethoxylated and optionally sulfated alkyl phenols, polyethoxylated fatty acids. These can be used at a rate of 0.1 to 3% use relative to the total mass of the formulation.

According to another of its aspects, the present invention relates to the use of the formulation as defined above as a coating base for the production - at very high speed - of crosslinked elastomeric coatings which are non-stick and water-repellent on a solid support. , preferably chosen:

Among the sheets of polymer material or of paper, cardboard or the like,

• among the adhesive tapes on their non-adhesive side,

• among the interlayer films of double-sided adhesive tapes. • or among the fibrous supports woven or not and / or composite or not.

The present invention also relates to the solid support at least partially coated with the aid of the formulation as defined above.

As is apparent from the above, the silicone formulation according to the invention can be applied directly to the support to be coated or alternatively, according to a variant, after treatment of the latter using a pre-layer making it possible to reduce the penetration of the anti-adhesion agent or agents into the support and / or of reducing the sensitivity of the support to water, said pre-layer being obtained by coating by means of an aqueous emulsion based on a functionalized polyorganosiloxane grafted with unsaturated units, for example of the acrylic type.

Thus, the present invention also relates to a process for producing - at very high speed - crosslinked elastomeric coatings non-stick and water-repellent on a solid support, characterized in that it essentially consists:

^ coating the solid support with a pre-coating based on graft functionalized polyorganosiloxanes and comprising graft copolymer units derived from at least one ethylenically unsaturated monomer capable of polymerizing by the radical route and of a functionalized polyorganosiloxane (A) containing units (A) similar or different of the following formula (A):

RaYbXc Si O (4-a-b-c) / 2

formula in which:

- the symbols R are similar or different and represent a linear or branched C 10 alkyl group, a linear or branched C ₂₀ alkenyl group, a C ₆ -C ₁ aryl or aralkyl group, optionally substituted by atoms halogen; - the symbols X are similar or different and represent an epoxyfunctional hydrocarbon group, containing from 2 to 20 carbon atoms and linked to a silicon atom by a Si-C or Si-OC bond; the symbols Y are similar or different and represent an ethylenically unsaturated hydrocarbon residue which may contain one or more heteroelement (s) O or N, this residue being linked to a silicon atom of the motif of formula (A) by an Si-C bond and being capable of reacting radically with said ethylenically unsaturated monomer (s); - a, b and c are equal to 0, 1, 2 or 3;

- a + b + c = 0, 1, 2 or 3; the rate of SiO _{4/2 units} being less than 30% by mole; the number of units of formula (A) in which the silicon atom carries a function X and / or a residue Y, being such that said polyorganosiloxanes contain:

- at least 1 milliequivalent, preferably from 5 to 500 milliequivalents, and even more preferably from 5 to 100 milliequivalents of functions X per 100 grams of polyorganosiloxane of formula (A), - at least 5 milliequivalents, preferably from 10 to 500 milliequivalents, of residues Y per 100 grams of polyorganosiloxane of formula (A), ι then to coat this pre-coating using the formulation as defined above, so as to obtain a crosslinked elastomeric coating that is non-stick and water-repellent.

As described in PCT application WO-01/04 418, the graft functionalized polyorganosiloxane comprising the pre-layer can be combined with a polymeric material of acrylic type. For more details, refer to PCT WO-01/04 418.

Advantageously, the liquid silicone formulation according to the invention makes it possible to produce a non-stick silicone coating on a solid support comprising the precoat referred to in the process defined above as well as in PCT application WO-01/04418.

The present invention finally relates to a solid support at least partially coated using the formulation as defined above or obtained by the process in which a layer of a primer primer is produced, said solid support being characterized in that it is intended for adhesive labels.

The nonlimiting examples which follow will make it possible to better understand the invention and to grasp all of its advantages and variant embodiments.

EXAMPLES

Example 1: Adherence on paper

Conditions coating / polymerisation on coating Rotomec pilot oven ^1: 180 ° C / 2 ^nd oven: 200 ° C / 3 ^rd oven: 220 ° C Speed: 100 m / min

Deposit: 0.5 to 0.8 g / m ² with and without Corona treatment

Support: glassine paper "CENTURY 65" from MAC TAC.

CORONA treatment can be defined as follows: Shennan Treater GX10 device set to a power of 1KW for a width of 400mm.

The constituents of the liquid silicone formulations tested are chosen from the group comprising: (a) Poly 1 = Ninyleum oil at the end and middle of the chain, poly (dimethyl) (methylvinyl) siloxane α, ω bis vinyldimethylsiloxy, viscosity 235 cps, Ni content 0.033 moles / 100g.

Poly 2 = Ninyleum oil at the middle and end of the chain, poly (dimethyl) (methylvinyl) siloxane α, ω bis vinyldimethylsiloxy, viscosity 500 cps, Ni content 0.08 lmoles / 100g Poly 3 = oil SiH homopolymer, poly (dimethyl) siloxane α, ω bis hydrogen dimethylsiloxy, viscosity 20 cps, 1.55 moles of SiH / lOOg. Poly 4 = copolymer SiH oil, poly (dimethyl) (methyl hydrogen) siloxane α, ω bis hydrogen dimethylsiloxy, viscosity 25 cps, 1.33 moles of SiH / lOOg.

(b) Catalyst = Solution at 3000ρpm of Karsted Platinum in vinyl oil, viscosity 300 mPa.s.

** (c) Three attachment promoters are evaluated: GLYMO (IN.li), β- (3,4- epoxycyclohexyl) ethyltriethoxysilane (IN.l) (trade name Coatosil 1770 from

Witco Company), Butyl Titanate (IN.3). These attachment promoters are used in admixture. The list of formulations used is given in Table 1.

Table 1

Formulations A to H are control formulations. Formulations I to P are in accordance with the invention. Some of these formulations are evaluated using the following tests: - Smear test (fingerprint): evaluation of the level of crosslinking of the coating by qualifying the oily nature of the surface A, B, C, D. - Migration / Dewetting : on an adhesive having been in contact with the silicone coating, a thin line of Shearman ink with a surface tension of 31 mJ / m ^{2 is} deposited and the time taken by this ink to dewetting and forming droplets is monitored. This time is expressed in seconds. - Migration Scotch test: Peel strength: the test used meets the Finat standards n ° 3 and 10 of edition n ° 5 of 1999. This test is carried out 4 days after crosslinking ("offline") with ribbons adhesives sold under the brand Tesa® 7475 at 23 ° C (acrylic base), Tesa® 7476 at 70 ° C (rubber base). - Rub-off hanging: We rub with the index finger to coat it to determine the number of passes necessary for abrasion of the coating.

Table 2 below gives the coating conditions, the types of formulations tested and the results of the tests.

Table 2: Coating conditions / formulation type and evaluation results

The performance in the rub off test (0 poor / 10 excellent) is evaluated either after being placed in an oven for 15 days in an oven at 90% RH and 50 ° C., or after an adhesivation. These tests simulate natural aging of the complex. All the results obtained are collated in Tables 3-4-5-6.

Table 3: Results of the rub off test evaluations: tests with adhesion promoters without Corona treatment.

* We also follow the Rub off after adhesivation with an acrylic adhesive in aqueous phase.

Table 4: Results of the rub off test: tests without adhesion promoter without Corona.

Table 5: Results of the rub off test: tests without adhesion promoters with Corona.

The formulations not in accordance with the invention have very poor resistance to the rub off test. All the formulations according to the invention, added with promoter (IV) are good. On the other hand, they have no impact on the other performance of the coating: non-stick (peeling), polymerization.

Example 2: Evaluation of the additives on a PET support

The support tested is a PET stretch film ref 6001 from the company Toray. This film is not Corona treated. The list of formulations evaluated is grouped in Tables 6 and 7. It is recalled that a result of 10 in the rub off test is excellent while a result of 0 is bad. The rub off is measured just after coating / crosslinking and after a certain time of aging.

Coating / crosslinking conditions: Laboratory coatings EUCLLD Weight of coated silicone: 0.6 - 0.7g / m ² Crosslinking in an oven: 150 ° C / 10s

Table 6:

Coating / crosslinking conditions: Laboratory coatings EUCLLD Weight of coated silicone: 0.7 - 0.9g / m ² Crosslinking in an oven: 150 ° C and 30 s

Table 7

Right after coating, the rub off test performance is good for all formulations. After aging, only formulations U to Y according to the invention retain good performance in the rub off test. We see that the more additives, the better the good performance in the rub off test, lasts over time.

The polymers used are those of Example 1 except:

Poly 5 = Ninylée oil at the end of the chain, viscosity 1000 cps and a vinyl content of 0.0107 moles / 100g.

Example 3: Effect of Different Mixtures of IN Promoter According to the Invention with Respect to Attachment to a PET Support CORONA Treated

Different mixtures of butyl titanate / GLYMO in two non-stick silicone formulations with Polyl and Poly 5. Rub off tests are carried out before and after accelerated aging cycles: 1) Exposure to air at room temperature

2) Storage in a confined atmosphere at room T

3) Exposure to 100% relative humidity

All the other coating performances have been evaluated: modulation, polymerization.

Coating / crosslinking conditions on ROTOMEC coating machine Temperature of the 3 ovens: 180 ° C Machine speed: 80 m min Silicone deposit: 1.0 g / m ² ,

Power of the Corona treatment: 1.0 kWatt application just before siliconization. Support: PET 6001

Table 8 below gives the results obtained.

Table 8:

* In-line release: Peel test carried out according to the protocol defined above, at the exit of the coating machine.

Whatever the silicone formulation evaluated, a Corona treatment does not compensate for the absence of the IV adhesion promoter characteristic of the formulation according to the invention. On a PET film, the Corona treatment must be combined with the silicone formulation of the invention to obtain good performance in the rub off test. It is noted that the IN promoter which gives the best performance consists of a 50/50 Titanate (IN.3) / GLYMO (IN.li) mixture and it must be added at a rate of 5% in the silicone formulation. There is no impact of the additives, except with 4% titanate, on the non-stick performance of the coatings.

Claims

1 - Liquid silicone formulation, usable as a coating base for the production - at very high speed - of crosslinked non-stick and water-repellent elastomeric coatings on a solid support, this formulation comprising in particular: at least one silicone composition based on at at least one polyorganosiloxane (I) crosslinkable by polyaddition, by polycondensation, by cationic or radical route, under thermal and / or actinic activation and / or obtained using an electron beam, at least one catalyst / initiator (II ), possibly, at least one adhesion modulating system (III), characterized:

- in that it also comprises at least one adhesion promoter (IN) based on: “at least one of the following compounds (IV.1) and (1N.2): o (IN.1) at least one alkoxysilane comprising at least one epoxy radical, o (IN.2) at least one alkoxysilane containing, per molecule, at least one C2-C6 alkenyl group,

• and in addition: o (IN.3) at least one metal chelate M and / or a metal alkoxide of general formula M (OJ) _n , with n = valence of M and J = linear or branched Ci -C alkyl g.

M being chosen from the group formed by: Ti, Zr, Ge, Li, Mn, Fe, Al,

Mg; - in that the POS (s) of higher viscosity has (have) a dynamic viscosity η at 25 ° C less than 1000 mPa.s, preferably less than 900 mPa.s, and more preferably still less than 800 mPa .s,

2 - Silicone formulation according to claim 1 characterized in that the epoxidized alkoxysilane (IN.1.) Of the promoter (IN) is chosen:

in which :

. R is a linear or branched C1-C4 alkyl radical,

9. R is a linear or branched alkyl radical

. y is 0, 1, 2 or 3,

with Δ E and D which are identical or different radicals chosen from linear or branched C1-C4 alkyls,

Δ z which is equal to 0 or 1,

Δ R, R, R which are identical or different radicals representing hydrogen or a linear or branched Cι-C4 alkyl,

Δ R 3 and R 4 or R 5 can alternately constitute together with the two carbons carrying the epoxy, an alkyl ring having 5 to 7 members,

- or among the epoxidized alkoxysilanes (JN.lb) constituted by epoxyfunctional polydiorganosiloxanes comprising at least one motif of formula:

X _p G ₄ SiO _4. (P _{+ q) / 2} (IN. Lbi)

in which :

- X is the radical as defined above for the formula (IN.1 a)

- G is a monovalent hydrocarbon group, free from any unfavorable action on the activity of the catalyst and chosen from alkyl groups having from 1 to 8 carbon atoms included, optionally substituted by at least one halogen atom, and also from aryl groups, - p = 1 or 2,

- q = 0, 1 or 2,

- ρ + q = 1, 2 or 3,

optionally at least part of the other units of these polydiorganosiloxanes are units of average formula:

G ' _r SiO ₄ . _r / ₂ (JN.lbii) in which G has the same meaning as G defined above and _r has a value between 0 and 3.

3 - Formulation according to claim 1 or claim 2 characterized in that the alkenylated alkoxylane (IN.2) corresponding to the following general formula:

**

R ⁶ R ⁷ C ^ _/ (A) _;

C * \ _/ Si G "(OR ¹⁰ ) _3. _X

(1N.2)

in which :

- R 6, R 7, R R are hydrogenated or hydrocarbon radicals which are identical or different from each other and representing hydrogen, a linear branched C -C 4 alkyl or a phenyl optionally substituted by at least one C1-C3 alkyl,

- A is a linear or branched C1-C4 alkylene, or a divalent group of formula -CO-O-alkylene- ", where the alkylene residue is as defined above and the valence— is linked to Si via G,

- G is a valence link,

- x '= 0 or 1, - x = 0 to 2.

4 - Formulation any one of claims 1 to 3 characterized in that the metal M of the chelate and / or the alkoxide (1N.3) is chosen from the following list: Ti, Zr, Ge, Li, Mn. 5 - Formulation any one of claims 1 to 4 characterized in that the adhesion promoter comprises:

- (IV.1) of 3-Glycidoxypropyltrimethoxysilane (GLYMO),

- and / or 3-glycidoxypropylethoxysilane, - and / or β- (3,4-epoxycyclohexyl) - ethyltriethoxysilane,

- (IN.2) or vinyltrimethoxysilane (NTMO) and / or 3-methacryloxyxypropyltrimethoxysilane (MEMO),

- (IN.3) and butyl titanate.

6 - Formulation any one of claims 1 to 5 characterized in that the weight ratio (IN.l) or (IN.2) / (IN.3) is between 5 and 0.5, and preferably is around 1.

7 - Formulation according to any one of claims 1 to 6 characterized in that the adhesion promoter (IN) is present in an amount of 0.1 to 10% by weight relative to all of the constituents.

8 - Formulation according to any one of claims 1 to 7 characterized: - in that the composition is a mixture formed of: (1.1) at least one polyorganosiloxane having, per molecule, at least two alkenyl groups, in C2-C6 bonded silicon,

(1.2) at least one polyorganosiloxane having, per molecule, at least three hydrogen atoms bonded to silicon, in that the catalyst (II) is composed of at least one metal belonging to the platinum group, and in that it involves :

(N) optionally at least one crosslinking inhibitor.

9 - Formulation according to claim 8 characterized in that the polyorganosiloxane (1.1) has units of formula:

in which :

- T is an alkenyl group, - Z is a monovalent hydrocarbon group, free from any unfavorable action on the activity of the catalyst and chosen from alkyl groups having from 1 to 8 atoms of carbon included, optionally substituted by at least one halogen atom, and also among the aryl groups,

- a is 1 or 2, b is 0, 1 or 2 and a + b is between 1 and 3,

- optionally at least some of the other motifs are motifs of medium formula:

Z _c SiO ₄ . _{c / 2} (Llii)

in which Z has the same meaning as above and c has a value between 0 and 3.

10 - Formulation according to claim 9, characterized in that the polyorganosiloxane (1.2) comprises siloxyl units of formula:

Hd L _e SiO _4. (D + e) / 2 (I-2i) in which:

- L is a monovalent hydrocarbon group, free from any unfavorable action on the activity of the catalyst and chosen from alkyl groups having from 1 to 8 carbon atoms included, optionally substituted by at least one halogen atom, and also panni aryl groups, - d is 1 or 2, e is 0, 1 or 2, d + has a value between 1 and 3,

- optionally, at least some of the other motifs being motifs of medium formula:

L _g SiO ₄ -g ₂ (I.2ii)

where L has the same meaning as above and g has a value between 0 and 3.

11 - Formulation according to claim 9 or 10, characterized in that the proportions of (1.1) and of (1.2) are such that the molar ratio of the hydrogen atoms bonded to silicon in (1.2) on the alkenyl radicals bonded to silicon in (1.1), is between 0.4 and 10.

12 - Formulation according to any one of claims 1 to 11, characterized in that it is in the form of emulsion / aqueous dispersion. 13 - Use of the formulation according to any one of claims 1 to 12, as a coating base for the production - at very high speed - of crosslinked non-stick and water-repellent elastomeric coatings on a solid support, preferably chosen: sheets of polymer material or of paper, cardboard or the like,

• among the adhesive tapes on their non-adhesive side,

• among the interlayer films of double-sided adhesive tapes.

• or among the fibrous supports woven or not and / or composite or not.

14 - Solid support at least partially coated using the formulation according to any one of claims 1 to 12.

15 - Process for producing - at very high speed - crosslinked elastomeric non-stick and water-repellent coatings on a solid support, characterized in that it essentially consists of: - coating the solid support with a pre-coating based on grafted functionalized polyorganosiloxanes comprising graft copolymer units derived from at least one ethylenically unsaturated monomer capable of polymerizing by the radical route and from a functionalized polyorganosiloxane (A) containing similar or different units (A) of formula (A) below

R _a YbX _c Si O (4- -bc) / 2

formula in which:

- the symbols R are similar or different and represent a linear or branched Ci- o alkyl group, a linear or branched C ₂ -C ₂₀ alkenyl group, a C ₆ -Cι aryl or aralkyl group, optionally substituted by atoms halogen; - the symbols X are similar or different and represent an epoxyfunctional hydrocarbon group, containing from 2 to 20 carbon atoms and linked to a silicon atom by a Si-C or Si-OC bond; the symbols Y are similar or different and represent an ethylenically unsaturated hydrocarbon residue which may contain one or more heteroelement (s) O or N, this residue being linked to a silicon atom of the unit of formula (A) by an Si-C bond and being capable of reacting radically with said ethylenically unsaturated monomer (s);

- a, b and c are equal to 0, 1, 2 or 3;

at least 1 milliequivalent, preferably from 5 to 500 milliequivalents, and even more preferably from 5 to 100 milliequivalents of X functions per 100 grams of polyorganosiloxane of formula (A),

- at least 5 milliequivalents, preferably from 10 to 500 milliequivalents, of residues Y per 100 grams of polyorganosiloxane of formula (A),

- Then to coat this pre-coating using the formulation according to any one of Claims 1 to 13, so as to obtain a crosslinked elastomeric non-stick and water-repellent coating.

16 - Solid support at least partially coated using the formulation according to any one of claims 1 to 12 or obtained by the process according to claim 15 characterized in that it is intended for adhesive labels.