EP1456280A1

EP1456280A1 - Crosslinking agent for crosslinkable silicone composition with low platinum content based on hydrogenated silicone oil comprising si-h units in chain end and in the chain

Info

Publication number: EP1456280A1
Application number: EP02799829A
Authority: EP
Inventors: Jean-Paul Benayoun; Didier Dhaler; Jacques Kieffer; John White
Original assignee: Rhodia Chimie SAS
Current assignee: Elkem Silicones France SAS
Priority date: 2001-12-21
Filing date: 2002-12-19
Publication date: 2004-09-15
Also published as: JP4221300B2; FR2833963B1; US20050075020A1; JP2005512796A; US7273658B2; MXPA04006118A; WO2003054059A1; AU2002364466A1; FR2833963A1

Abstract

The invention concerns crosslinkable silicone compositions, useful for forming water-repellent and release coating for flexible heat-sensitive support. Said compositions comprise crosslinking polyorganosiloxanes (POS) bearing Si-H units and unsaturated POS, for example Si-Vi vinyl-containing POS, capable of reacting with the crosslinking agent by polyaddition, in the presence of platinum to form a release crosslinked coat on the flexible support. The invention aims at instantaneously enabling low platinum content crosslinking of such silicone compositions, coated at high speed. Therefor, the invention provides for the use of particular crosslinking agents consisting of hydrogenated POS comprising at least three hydrogen atoms bound to the silicon located at chain end and in the chain. The invention also concerns solvent-free or emulsion-type silicone compositions comprising the Si-Vi POS (I.1), the crosslinking agent Si-H POS (I.2) and the platinum catalyst, among others. The invention is useful for coating flexible supports, for example made of Lissé BEKK > 1000 paper.

Description

CROSSLINKER FOR A CROSSLINKABLE SILICONE COMPOSITION WITH BOTTOMS

PLATINUM RATE, BASED ON HYDROGENATED SILICONE OIL

COMPRISING Si-H PATTERNS AT THE END OF THE CHAIN AND IN THE CHAIN

The field of the invention is that of crosslinkable or crosslinked silicone compositions which can be used, in particular, to form a water-repellent and non-stick coating or film for fibrous support or not, for example made of paper or the like, or else in natural or synthetic polymer.

More specifically, the invention relates to silicone compositions of the type of those comprising: functionalized polyorganosiloxanes (POS) carrying, on the same molecule or not, Si-H and Si-IE units with IE representing a group comprising at least one unsaturation -ethylenic, preferably vinyl; the Si-H units being capable of reacting with the Si-IE units by polyaddition; a suitable metallic catalyst, preferably platinum; optionally at least one adhesion modulator system, for example based on silicone resin comprising siloxyl units Q: (SiO _{4 2} ) and / or T: (RSiO _3/2 ); possibly other additives (fillers, accelerators, inhibitors, pigments, surfactants ...). The invention also relates to the preparation of this type of silicone composition.

The invention also relates to the methods for manufacturing crosslinked silicone articles, in particular coatings, e.g. water-repellent and / or non-stick coatings for flexible or non-fibrous supports (paper or polymer film), from the above-mentioned compositions.

For example, these liquid silicone compositions (with / without solvent or in aqueous emulsion) are applied to the support films in industrial coating devices comprising rollers operating at very high speed (for example 600 m / min). It is clear that in these very high speed coating procedures, the viscosity of the liquid silicone coating composition must be carefully adapted to the coating operating conditions. The liquid silicone coating compositions in which we are more particularly interested in the context of the invention are solvent-free.

Alternatively, the silicone phase of these liquid silicone coating compositions may be diluted in a solvent. According to another more advantageous variant, in particular for health and safety reasons, the liquid silicone composition is an aqueous dispersion / emulsion.

In practice, the deposition rate of non-stick silicone is between 0.1 and 2, preferably 0.3 and 1 g / m, which corresponds to thicknesses of the order of a micrometer. Once applied to the flexible support, the silicone composition crosslinks to form a solid coating of silicone (eg elastomer) non-stick and / or water-repellent.

In the case of liquid silicone systems without solvent crosslinking by polyaddition [Si-H / Si-alkenyl- (Vi) -], the crosslinking is carried out under thermal activation.

Taking into account the industrial rates of coating at very high speed, the crosslinking kinetics must be instantaneous and the crosslinking must be correct, that is to say that the non-stick silicone films must be sufficiently crosslinked to be able to fill at best their anti-adhesion function and possess the desirable mechanical qualities. The assessment of the quality of the crosslinking of the non-stick silicone film can in particular be done through the dosage of extractable non-crosslinked compounds, the quantity of which must be as small as possible.

The anti-adhesion of the free 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. .

It is also important that these silicone coating compositions, crosslinkable by hydrosilylation eg ≡Si-H / ≡Si-Vi, have a lifetime at room temperature as long as possible, when they are in the form of coating bath in industrial coating machines.

The flexible supports coated with a non-stick silicone film can for example be:

- an adhesive tape, the internal face of which is coated with a layer of pressure-sensitive adhesive and the external face of which has 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;

- or a polymer film of the polyvinyl chloride (PNC), PolyPropylene, Polyethylene or PolyEthyleneTerephthalate type.

Another major constraint in these silicone coating compositions, crosslinkable by hydrosilylation eg ≡Si-H / ≡Si-Vi, in the presence of platinum, is precisely linked to their platinum content. Indeed, platinum is, because of its cost, a preponderant element of the cost price of a polyaddition system, in particular for the application of non-stick and / or water-repellent silicone coating, for flexible supports (paper or polymer film).

However, if, for reasons of economy, the level of platinum is reduced to a rate less than 100 or even 80 ppm in the composition, it is then no longer possible to obtain non-stick silicone coatings and / or water repellent, perfectly cross-linked.

In general, the use of crosslinking agents of the type of those comprising siloxy units is already disclosed: dimethylhydrogenosiloxy (M '), methylhydrogenosiloxy (D'), dimethylsiloxy (D) and trimethylsiloxy (M), for crosslinkable liquid silicone compositions by polyaddition (≡Si-H / Si- Vinyl), to form non-stick coatings on flexible supports (coated or uncoated papers, polymer films ...).

This is the case in patent application EP-A-0 523 660 which describes silicone compositions which can be crosslinked in a few seconds at temperatures below 100 ° C. and comprising POS ≡Si-Vi resins in a network (non-linear) and crosslinkers POS ≡Si-H type MD ', MDM'. It is not shown in this document that for low platinum levels (less than 100 ppm) the crosslinking of the silicone films obtained is correct. The level of extractables is not measured in the examples. The only platinum level mentioned in these is 100 ppm.

In EP-A-0 523 660 there is no particular POS POSSi-H crosslinking agent which confers advantageous properties on the crosslinked coating, in terms of reduced extractable content and duration of stability of the silicone composition bath. coating liquid, in particular.

In this context, the essential objective of the present invention is to propose a new use of particular POS ≡Si-H as crosslinking agents in liquid silicone coating compositions, crosslinkable in non-stick and / or water-repellent coating for flexible support, under thermal activation, with a low level of metallic catalyst (eg Pt), instantaneously and leading to crosslinked silicone coatings of very good quality, characterized by reduced extractable rates and moreover provided with excellent properties of attachment, in particular on smooth supports, for example in glassine paper by Lissé BEKK greater than 1000. Another essential objective of the invention is to propose a new use of

POS ≡Si-H particular as crosslinking agents in liquid silicone coating compositions, crosslinkable in non-stick and / or water-repellent coating for flexible support, under thermal activation, with low levels of metallic catalyst (eg Pt), instantaneously while having long lifetimes in the bath, at room temperature. Another essential objective of the invention is to propose a new use of

POS ≡Si-H particular as crosslinking agents in liquid silicone coating compositions, crosslinkable in non-stick and / or water-repellent coating, for flexible support, under thermal activation, with low level of metallic catalyst (eg Pt), of instantly and leading to correctly crosslinked silicone coatings and having entirely satisfactory anti-adhesion properties.

Another essential objective of the invention is to propose a new use of particular POS ≡Si-H as crosslinking agents in liquid silicone coating compositions, crosslinkable in non-stick and / or water-repellent coating for flexible support, under activation thermal, with low levels of metallic catalyst (eg Pt), instantaneously and leading to silicone coatings crosslinked correctly and having bonding properties, entirely satisfactory.

Another essential objective of the invention is to propose a new use of particular POS ≡Si-H as crosslinking agents in liquid silicone coating compositions, crosslinkable in non-stick and / or water-repellent coating for flexible support, under activation thermal, with low levels of metallic catalyst (eg Pt), instantaneously and leading to silicone coatings crosslinked correctly and having mechanical properties, entirely satisfactory. Another essential objective of the invention is to propose a new use of

POS ≡Si-H particular as crosslinking agents in liquid silicone coating compositions, crosslinkable in non-stick and / or water-repellent coating for flexible support, under thermal activation, with low levels of metallic catalyst (eg Pt), instantly and leading to silicone coatings crosslinked correctly and having water repellency properties, quite satisfactory.

Another essential objective of the invention is to propose a new liquid silicone coating composition, crosslinkable in non-stick and / or water-repellent coating for flexible support, under thermal activation, with low levels of metallic catalyst (eg Pt), instantaneously, this composition also having the same qualities as those mentioned above for use.

Another essential objective of the invention is to propose a new liquid silicone coating composition, crosslinkable in non-stick and / or water-repellent coating for flexible support, under thermal activation, with low levels of metallic catalyst (eg Pt), instantly, this composition also being easy to prepare and economical.

Another essential objective of the invention is to propose a production process, under thermal activation, with low levels of metallic catalyst (e.g. Pt), of crosslinked non-stick and / or water-repellent silicone coatings, on flexible supports.

These objectives, among others, are achieved by the present invention which firstly relates to a new use as a crosslinker (1.2), in a silicone composition capable of crosslinking by polyaddition, to form a coating, water-repellent and non-stick. for fibrous support or not, ^ of at least one silicone oil comprising at least one (preferably linear) hydrogenated PolyOrganoSiloxane (POS) having, per molecule, at least three hydrogen atoms bonded to silicon, and preferably of the following average formula:

M _α M ' _β D _γ D's

with M = (R ') ₃ SiOι _{/ 2}

M '= at 3

D = (R ² ) ₂ SiO _2/2

D '= HR ³ SiO _2/2

0 <α <2

0 <β <2

0 <γ

0 <δ

and with:

- ι 0 <γ / δ <0.4

→ 20 <(β / δ) x l000 <60,

^ the POS (s) with the highest viscosity of said composition having a dynamic viscosity η at 25 ° C less than or equal to 1500 mPa.s; *. the metal catalyst level being less than or equal to 80 ppm, preferably less than or equal to 65 ppm, and, more preferably still between 30 and 55 ppm.

The use according to the invention of judiciously selected POS ≡Si-H crosslinkers makes it possible to produce, with low platinum levels, therefore economically, non-stick coatings on flexible supports. Thanks to the invention, correct crosslinking of the coating is ensured at platinum levels of less than 80 ppm, preferably of the order of 60 ppm, and ideally of 40 ppm, for example, and this under industrial coating conditions. , eg at a temperature of 150 ° C.

Furthermore, these new POS ≡Si-H crosslinkers do not modify the rheological behavior of the silicone composition, so that it is perfectly suitable for being coated on any support and in particular on any flexible support. This latter property is all the more advantageous since, in the context of the invention, the silicone coating compositions can advantageously be "solvent-free". This means that they are solvent-free and, in particular, solvent-free organic. It is easy to see the advantages that this provides in terms of health and safety.

The performances achieved thanks to the invention in terms of quality of crosslinking by polyaddition: reactivity / level of crosslinking / kinetics, are quite interesting, as evidenced by the low levels of extractables obtained, as regards reactivity and the level of crosslinking.

The same applies to the attachment on supports, in particular on flexible supports (for example paper) very smooth.

Thus, the use according to the invention is distinguished by the fact that the silicone composition used can be transformed according to a determined methodology M, into a crosslinked elastomeric silicone coating, on a paper support whose smoothness BEKK is greater than 1000 , said coating being characterized by a positive attachment in a determined T test.

The M methodology and the T test are defined below in the examples. The formula of the crosslinker POS ≡Si-H (1.2) indicated above is a global formula which covers:

* -a- the cases where the POS crosslinker ≡Si-H (1.2) comprises the M M'D D 'units on the same POS molecule (preferably linear), the crosslinker possibly comprising one or more M M'D D molecules 'different, * -b- the cases where the POS crosslinker ≡Si-H (1.2) is formed by a mixture of POS molecules (preferably linear) each carrying a part of the units M M'D D', -c - the cases where the POS ≡Si-H (1.2) crosslinker is formed by a mixture of POS ≡Si-H (1.2) crosslinkers (preferably linear) of types -a- and -b-, as described above .

As examples of POS ≡Si-H (1.2) crosslinkers of type -b-, mention may be made of mixtures of POS ≡Si-H comprising units M and D 'and of POS comprising units M, D and D 'or mixtures of POS ≡Si-H (1.2) comprising units M and D and POS comprising units M', D and D ', or mixtures of POS ≡Si-H (1.2) comprising units M and D 'and POS comprising units M and D, or mixtures of POS ≡Si-H (1.2) comprising units M' and D 'and POS comprising units M and D.

The invention also covers variants in which the crosslinker (1.2) comprises hydrogenated POS motif-bearing T: RSiO _{_3/2} or Q: SiO _4/2. It can be, for example, POS ≡Si-H (1.2) of structure M'DD'QM '. As follows from cases -b-, the crosslinker with patterns M 'and D' according to the invention can also comprise standard crosslinkers POS ≡Si-H (1.2) having no M 'functions. Preferably, the silicone composition involved in the use according to the invention consists of POS ≡Si-H (1.2) and POS ≡Si-alkenyl (1.1) (eg Vi), of linear structure - possibly branched -, to exclusion of POS ≡Si-H (1.2) and POS ≡Si-alkenyl (1.1) (eg Vi) having a network cross-linked structure.

According to an advantageous embodiment of the invention, the support intended to be coated is made of thermosensitive material, preferably flexible, and, more preferably still chosen from flexible supports made of paper, cardboard or the like, the flexible supports constituted by the adhesive face of '' a label or a ribbon of the same name, flexible fibrous supports woven or not, flexible supports comprising polyethylene and / or polypropylene and / or polyester and / or polyvinyl chloride, and / or flexible supports thermally printable.

According to the invention, for the crosslinking of the coating, the support coated with the polyaddition silicone composition is placed at a temperature greater than or equal to 110 ° C, preferably between 110 and 250 ° C, and more preferably still between 130 and 170 ° C, for less than 60 seconds, preferably less than 10 seconds.

Advantageously, the silicone composition is a mixture formed of: (1.1) at least one POS having, per molecule, at least two alkenyl groups

(preferably in C2-C6) linked to silicon,

(1.2) at least one cross-linking POS ≡Si-H as defined above,

(1.3) and / or at least one POS carrying Si-alkenyl and Si-H units,

(II) at least one catalyst (II) composed of at least one metal belonging to the platinum group.

Preferably, at least one POS (1.1) of Si-alkenyl type, for example Si-Vi, and at least one POS (1.2) of Si-H type is used.

POS (1.1) is by weight one of the essential constituents of the formulation.

Advantageously, this POS (1.1) is a product comprising units of formula:

^w ^ ° ^ - ⁽¹⁾

in which W is an alkenyl group, preferably vinyl or allyl, - Z is a monovalent hydrocarbon group, free of unfavorable action on the activity of the catalyst and preferably chosen from alkyl groups having from 1 to 8 carbon atoms included , advantageously, among the methyl, ethyl, propyl and 3,3,3-trifluoropropyl groups and also among the aryl groups and, advantageously, among the xylyl and totyl and phenyl radicals, a is 1 or 2, b is 0, 1 or 2 and a + b is between 1 and 3.

It is advantageous for this polydiorganosiloxane to have a viscosity (at 25 ° C.) at least equal to 10 mPa.s, preferably between 50 and 1,000 mPa.s.

All the viscosities in question in this presentation correspond to a quantity of dynamic viscosity at 25 ° C called "Newtonian", that is to say the dynamic viscosity which is measured, in a manner known per se, at a gradient sufficiently low shear speed so that the viscosity measured is independent of the speed gradient.

The polyorganosiloxane (1.1) can have a linear, branched or cyclic structure. Its degree of polymerization is preferably between 2 and 5000.

Examples of siloxyl units of formula (1.1) are the vinyldimethylsiloxane unit, the vinylphenylmethylsiloxane unit and the vinylsiloxane unit.

Examples of polyorganosiloxanes (1.1) are dimethylpolysiloxanes with dimethylvinylsilyl ends, methylvinyldimethylpolysiloxane copolymers with trimethylsilyl ends, methylvinyldimethylpolysiloxane copolymers with dimethylvinylsilyl ends, cyclic methylvinylpolysiloxanes. The crosslinking polyorganosiloxane (1.2) is preferably of the type of those comprising siloxyl units of formula:

H .SiO _Λ ,. . (1.2)

in which: - L is a monovalent hydrocarbon group, free from any unfavorable action on the activity of the catalyst and preferably chosen from alkyl groups having from 1 to 8 carbon atoms included and, advantageously, from methyl groups, ethyl, propyl and 3,3,3-trifluoropropyl and also among the aryl groups and, advantageously, among the xylyl and totyl and phenyl radicals, - d is 1 or 2, e is 0, 1 or 2, d + a value between 1 and 3. The dynamic viscosity ηd (at 25 ° C) of this polyorganosiloxane (1.2)> to 5 preferably to 10 and, more preferably still, is between 20 and 1000 mPa.s.

The polyorganosiloxane (1.2) can have a linear, branched or cyclic structure. The degree of polymerization is greater than or equal to 2. More generally, it is less than 5,000.

Examples of units of formula (1.2) are: M ': H (CH) SiOi / 2, D': HCH ₃ Siθ2 / 2, D ': H (C6H ₅ ) Siθ2 / 2.

Examples of polyorganosiloxane (1.2) are: - M'DD ': dimethylpolysiloxanes with hydrogenodimethylsilyl ends, poly (dimethylsiloxane) (methylhydrogenosiloxy) α, ω-dimethylhydrogeno-siloxane,

- MDD ': copolymers with dimethyl-hydrogenomethylpolysiloxane (dimethyl) units with trimethylsilyl ends,

- M'DD ': copolymers with dimethyl-hydrogenomethylpolysiloxane units with hydrogenodimethylsilyl ends,

- MD ': hydrogenomethylpolysiloxanes with trimethylsilyl ends,

- D ' ₄ : the cyclic hydrogenethylpolysiloxanes.

The bases of polyaddition silicone compositions may contain only linear polyorganosiloxanes (II) and (1.2) such as, for example, those described in the patents: US-A-3,220,972, US-A-3,697,773 and US-A- 4,340,709.

The catalysts (II) are also well known. The compounds of platinum and rhodium are preferably used. It is possible, in particular, to use the complexes of platinum and of an organic product described in patents US-A-3,159,601, US-A-3,159,602, US-A-3,220,972 and European patents EP- A-0 057 459, EP-A-0 188 978 and EP-A-0 190 530, the complexes of platinum and vinylated organosiloxanes described in the patents US-A-3,419,593, US-A-3,715,334 , US-A-3,377,432 and US-A-3,814,730. The generally preferred catalyst is platinum. In this case, the quantity by weight of catalyst (H), calculated by weight of platinum-metal, is generally between 2 and 400 ppm, preferably between 5 and 200 ppm based on the total weight of the polyorganosiloxanes (II) and (1.2 ).

Preferably, the crosslinking POS has a ≡Si-H / ≡Si-alkenyl (Vi) molar ratio, such as:

1.0 <≡Si-H / ≡Si-alkenyl (Vi) <4 preferably 1, 4 <≡Si-H / ≡Si-alkeny le (Vi) <3.

It is advantageous that the POS (II) is a linear polydiorganosiloxane blocked with "Si-alkenyl" functions - preferably located at the end of the chain -, having a viscosity of the order of 100 to 1000 mPas and a rate of alkenyl functions t _a , expressed in number of equivalent of alkenyl functions per 100 g of oil:

0.01 <t _a preferably 0.015 <t _a <0.04 and even more preferably 0.015 <t _a <0.1.

Likewise, the oil useful as crosslinker comprising at least one POS with iSi-H (1.2) functions has - preferably - a viscosity of the order of 5 to 150 mPas.

The complete curable compositions are fluid at normal temperature; their viscosity is generally of the order of 50 to 500 mPa.s. at 25 ° C.

According to one variant, the crosslinkable non-stick silicone composition contains:

• at least one adhesion modulator system (III); • and / or at least one hydrosilylation inhibitor agent (IV), preferably chosen from acetylenic alcohols and / or diallylmaleates and their derivatives;

• optionally at least one other additive chosen from bactericides, and / or antifreeze agents, and / or wetting agents, and / or anti-foam agents and / or fillers, and / or synthetic latexes, and / or dyes , and / or acidifiers.

The adhesion modulator system (III) is selected from known systems. These may be those described in French patent FR-B-2 450 642, US patent -B- 3 772 247 or European patent application EP-A-0 601 938. By way of examples, may include modulators based on: o from 96 to 85 parts by weight of at least one reactive polyorganosiloxane resin (A) of type: MD ^vi Q, MM ^Vi Q, MD ^vi T, MM ^Héxén yleQ, _{0 or} _MM AllyloxypropyleQ. o from 4 to 15 parts by weight of at least one non-reactive resin (B) of the type: MD'Q, MDD'Q, MDT ', MQ, or MDQ.

The retarder of the addition reaction (IV) (crosslinking inhibitor) can, for its part, be chosen from the following compounds: polyorganosiloxanes, advantageously cyclic and substituted with at least one alkenyl, tetramethylvinyltetrasiloxane being particularly preferred, pyridine, phosphines and organic phosphites, unsaturated amides, alkyl maleates and acetylenic alcohols. These acetylenic alcohols, (cf. FR-B-1 528 464 and FR-A-2 372 874), which are part of the preferred hydrosilylation reaction thermal mockers, have the formula:

R ¹ - (R ² ) C (OH) - C ≡ CH formula in which:

. R ¹ is a linear or branched alkyl radical, or a phenyl radical; . R ² is H or a linear or branched alkyl radical, or a phenyl radical; the radicals R, R and the carbon atom located at the triple bond which can optionally form a ring; the total number of carbon atoms contained in R and R being at least 5, preferably from 9 to 20.

Said alcohols are preferably chosen from those having a boiling point above 250 ° C. As examples, we can cite:. ethynyl-1-cyclohexanol 1; . 3-methyl-dodecy-1 ol-3; . trimethyl-3,7,11 dodécyne-1 ol-3; . dipheny 1-1,1 propyne-2 ol-1;

. 3-ethyl-6-ethyl nonyne-1 ol-3; . 3-methyl-pentadecyne-1 ol-3. These α-acetylenic alcohols are commercial products.

Such a retarder is present at a rate of 3000 ppm at most, preferably at the rate of 100 to 2000 ppm relative to the total weight of the organopolysiloxanes (I.l) and (1.2).

According to another implementation route different from that "without solvent", the composition is in the form of an aqueous emulsion / dispersion and then comprises at least one surfactant; and optionally at least one pH-fixing agent. The agent for fixing and maintaining the pH is preferably a buffer system comprising HCO ₃ / CO ₃ and / or H ₂ PO ₄ / HPO ₄ . Thus, to obtain the desired buffering effect, it will be necessary to introduce, in accordance with the invention, a salt of HCO ₃ "and / or H ₂ PO ₄ " such as for example NaHCO ₃ and / or Na ₂ CO ₃ and / or NaH ₂ PO ₄ and / or Na ₂ HPO ₄ . It goes without saying that any other salt with a different counter anion (eg K) could be suitable. In a particularly preferred manner, a buffer system constituted by NaHCO _{3 is used in practice} which is incorporated into the emulsion. The surfactant (s) capable of being present in the emulsion according to the invention as an emulsifying agent are of non-ionic or ionic nature.

According to an advantageous arrangement, the proportion of water in the emulsion is greater than or equal to 50% by weight, preferably greater than or equal to 55% by weight and for example in practice of the order of 55 - 60% by weight or even 85 to 90% by weight.

According to another of its objects, the invention relates to a silicone composition capable of crosslinking by polyaddition, to form a coating, water-repellent and non-stick for fibrous support or not, characterized: in that it comprises: (II) at least a POS having, per molecule, at least two alkenyl groups (preferably C2-C6) linked to silicon, (1.2) of at least one silicone oil: • comprising at least one linear hydrogenated PolyOrganoSiloxane (POS) having, per molecule , at least three hydrogen atoms bonded to silicon, • and of the following average linear formula:

M _α M ' _p D _γ D' _δ

with M = (R ') ₃ SiOι ₂

M '= , a + b = 3, a = l, 2 or 3, b = 0 to 3

D = (R ² ) ₂ SiO _2/2

D '= HR ³ SiO _2/2

0 <α <2

0 <β <2

0 <γ

0 <δ

and with:

→ 0 <γ / δ <0.4

→ 20 <(β / δ) x l000 <60

^ at least one catalyst (II) composed of at least one metal belonging to the platinum group; said catalyst being present at a metal catalyst level being less than or equal to 80 ppm, preferably less than or equal to 65 ppm, and, more preferably still between 30 and 55 ppm. and in that the POS (s) with the highest viscosity that it contains, has (have) a dynamic viscosity η at 25 ° C less than or equal to 1500 mPa.s.

To define the composition according to the invention, reference is made to the characteristics defined above in the context of the description of the use.

According to another of its aspects, the present invention relates to a process for preparing a silicone composition, which can be used in particular as a coating base for the production of non-stick and water-repellent coatings, this composition being of the type defined above. . According to this method, at least one POS (II) ≡Si-Vi oil (preferably linear) is mixed with the crosslinker constituted by at least one POS (1.2) ≡Si-H oil of MM'DD type and or by a mixture of oils comprising POS molecules (preferably linear) each carrying a part of the M M'D D 'units contained in the crosslinker. The catalyst (II) is also incorporated into the silicone phase, with any other ingredients such as crosslinking inhibitors. The mixing means and methodologies are known to those skilled in the art, whether they are compositions with / without solvent or emulsion.

These compositions can be applied using devices used on industrial paper coating machines such as a five-roller coating head, air knife or equalizer bar systems, on supports or materials. flexible, then hardened by circulation in tunnel ovens heated to 70-200 ° C; the passage time in these ovens is a function of the temperature; this is generally on the order of 5 to 15 seconds at a temperature on the order of 100 ° C. and on the order of 1.5 to 3 seconds at a temperature on the order of 180 ° C. Said compositions can be deposited on any flexible material or substrate such as papers of various types (supercalendered, coated, glassine), cardboards, cellulose sheets, metal sheets, plastic films (polyester, polyethylene, polypropylene ...). ..

The quantities of compositions deposited are of the order of 0.5 to 2 g per m ² of surface to be treated, which corresponds to the deposition of layers of the order of 0.5 to 2 μm.

The materials or supports thus coated can subsequently be brought into contact with any adhesive, rubber, acrylic or other, pressure-sensitive materials. The adhesive material is then easily detachable from said support or material.

According to another of its aspects, the present invention relates to a support characterized in that it comprises at least one non-stick coating obtained:

"in accordance with the use as defined above," and / or from a composition as defined above. The following examples are given for information only and cannot be considered as limiting the scope and spirit of the invention.

EXAMPLES:

-1- Coating / Crosslinking of the silicone coating according to a determined M methodology The silicone composition is coated on a Rotomec coating pilot (while maintaining a residence time in ovens of 1.8 s) on glassine 9564 paper support, including the smoothness BEKK is around 1020.

The temperature of the silicone layer is measured online using an infrared camera. The temperature of the support is of the order of 150 ° C.

-2- Characterization of the silicone coating crosslinked on the support The coating is characterized after coating and crosslinking by the following tests:

Weight of the silicone coating: The silicon atoms of the coating are excited using a radioactive source or a fluorescent tube X and the intensity X re-emitted by the coating is measured. By means of a calibration, the weight of the silicone coating is thus determined. The apparatus used has for reference Lab XI 000 marketed by the company Oxford.

Rate of extractables (leaving the coating machine: "in-line" / 4 days after crosslinking: "off-line"): the test consists of immersing the coating in toluene and then assaying by absorption spectrophotometry atomic Perkin Elmer 3100 (the silicone having transferred into the solvent By means of a calibration, the amount of silicone extractable from the coating is accessed.

Crosslinking: we qualify the level of polymerization of the coating at the outlet of the coating machine through a number of business tests: "smear" where we qualify the oily nature of the surface by passing the finger on the surface silicone.

The test of "rub off" (Test T) which characterizes the attachment to the support. In practice we rub with your finger on the surface of the coating and note the number of passes from which the coating degrades / takes off. note of 10 (10 passages) is considered acceptable for the application: POSITIVE HANGING.

Peel strength: the test used corresponds to Finat standards n ° 3 and 10 of edition n ° 5 of 1999. This test is carried out 4 days after crosslinking ("off- line ") with adhesive tapes sold under the brand Tesa® 7475 at 23 ° C (acrylic base), Tesa® 7476 at 70 ° C (rubber base). Control of instant adhesion performance without PSA" tack "pressure after contact with the silicone coating according to standard No. 9 of the Finat edition No. 5 of 1999.

-3- Products used

• Vinylized silicone oil in and at the end of the chain (I.l): vinylated PolyDiMethylSiloxane oil with 0.033 mole of Vi / 100g and viscosity at 25 ° C = 230 mPa.s. This oil contains 0.15% inhibitor

EthynylCycloHexanol (IV).

• Modulator (III) mixture of vinylated silicone oil and of a vinylized MQ resin (50/50 mixture), containing 0.107 vi / 100g groups. this modulator contains 0.15% ECH inhibitor (IV). • Catalyst (II): Pt Karstedt containing 2000 ppm of Pt.

• Crosslinker (1.2) based on oil or mixture of hydrogenated PDMS Silicone Oil: the characteristics of these products are given in the following table.

-4- The tests and their results

4.1 - TESTS

Several hydrogenated silicone oils have been tested comparatively. The characteristics of these oils are given in Table 1 below.

TABLE 1

These crosslinkers are formulated with vinyl oil ((II), the modulator (1.3) and the catalyst

(II).

The formulation rules followed are:

- Si-H / Si-Vi ratio of 2.2

- rate of pt in the final formulation: 60 ppm

- 40% modulator rate.

4.2 - FORMULAS

These formulations are coated on a glassine paper ref 9564 from Lissé BEKK of the order of 1020 from the company Ahlstrom, the weight of silicone deposited is of the order of ^1.2 g / m ² . The crosslinking conditions over 1.8 s with a coating temperature of 150 ° C. 4.3 - SNAP AND EXTRACTABLE EVALUATION

In Table 3 below, the performances in the rub off test have been grouped together with the rate of extractables leaving the oven of the formulations evaluated. It should be remembered here that we are looking for a low rate of extractables (sign of extensive polymerization) and good resistance to the rub off test.

TABLE 3

It is clearly seen that the crosslinkers (1.2) according to the invention of structure POS ≡Si-H: M'MD'D (tests 1, 2, 11) make it possible to obtain the lowest extractable rates, signature of better reactivity with good attachment to the support. The invention provides access to crosslinkable formulations with low Pt levels.

Claims

-1- Use as a crosslinker (1.2), in a silicone composition capable of crosslinking by polyaddition in the presence of a metal catalyst, to form a coating, water-repellent and non-stick for fibrous support or not, i. at least one silicone oil comprising at least one (preferably linear) hydrogenated PolyOrganoSiloxane (POS) having, per molecule, at least three hydrogen atoms bonded to silicon, and preferably of the following average formula:

M _α M ' _β D _γ D' _δ

with M = (R ^ SiO. ^

M '= H _a (R') _b SiOι _{/ 2} , a + b = 3, a = l, 2 or 3, b = 0 to 3 D = (R ² ) ₂ Siθ2 / ₂ D * = HR ³ SiO _{2 2}

0 <α <2 0 <β <2 0 <γ 0 <δ

and with:

- ι 0 <γ / δ <0.4

-ι 20 <(β / δ) x l000 <60,

^ the POS (s) with the highest viscosity of said composition having a dynamic viscosity η at 25 ° C less than or equal to 1500 mPa.s; the metal catalyst level being less than or equal to 80 ppm, preferably less than or equal to 65 ppm, and, more preferably still between 30 and 55 ppm.

-2- Use according to claim 1, characterized in that the silicone composition is such that it can be transformed according to a determined methodology M, into a crosslinked elastomeric silicone coating, on a paper support whose smoothness BEKK is greater than 1000 , said coating being characterized by a positive attachment in a determined T test. -3- Use according to claim 1 or 2, characterized in that the support intended to be coated is of thermosensitive material, preferably flexible, and, more preferably still chosen from flexible supports of paper, cardboard or the like, flexible supports consisting of the adhesive side of a label or a ribbon of the same name, flexible fibrous supports woven or not, flexible supports comprising polyethylene and / or polypropylene and / or polyester and / or polyvinyl chloride, and / or thermally printable flexible supports.

-4- Use according to claim 1, characterized in that for the crosslinking of the coating, the support is placed at a temperature less than or equal to 110 ° C, preferably less than or equal to 100 ° C, and more preferably still included between 75 and 95 ° C, for less than 60 seconds, preferably less than 10 seconds.

-5- Use according to claim 1, characterized in that the silicone composition is a mixture formed of:

(1.1) at least one POS ≡Si-alkenyl having, per molecule, at least two alkenyl groups (preferably C2-C6) bonded to silicon,

(1.2) at least one cross-linking POS ≡Si-H as defined above,

(1.3) and / or at least one POS carrying Si-alkenyl and Si-H units, (II) at least one catalyst (II) composed of at least one metal belonging to the platinum group.

-6- Use according to claim 5, characterized in that the crosslinking POS has a molar ratio ≡Si-H / ≡Si-alkenyl (Vi), such that: 1.0 <≡Si-H / ≡Si-alkenyl ( Vi) <4 preferably 1, 4 <≡Si-H / ≡Si-alkenyl (Vi) <3.

-7- Use according to claim 6, characterized in that the POS (I.l) is a product comprising units of formula:

in which :

W is an alkenyl group, preferably vinyl or allyl,

- Z is a monovalent hydrocarbon group, free from any unfavorable action on the activity of the catalyst and preferably chosen from alkyl groups having from 1 to 8 carbon atoms included, advantageously, among the methyl, ethyl, propyl and 3,3,3-trifluoropropyl groups and also among the aryl groups and, advantageously, among the xylyl and totyl and phenyl radicals, a is 1 or 2, b is 0, 1 or 2 and a + b is between 1 and 3.

-8- Use according to any one of claims 1 to 7, characterized in that the crosslinkable non-stick silicone composition contains:

- at least one adhesion modulating system (III),

- And / or at least one hydrosilylation (IV) inhibiting agent.

-9- Use according to any one of claims 1 to 8, characterized in that the POS (II) is a linear polydiorganosiloxane blocked with "Si-alkenyl" functions - preferably located at the end of the chain -, having a viscosity of of the order of 100 to 1000 mPas and a rate of alkenyl functions t _a , expressed in number of equivalent of alkenyl functions per 100 g of oil:

0.010 <t _a preferably 0.015 <t _a <0.04 and even more preferably 0.015 <t _a <0.10.

-10- Use according to any one of claims 1 to 9, characterized in that the oil useful as crosslinker and comprising at least one POS with ≡Si-H functions (1.2), has a viscosity of the order of 5 at 150 mPas.

-11- Use according to any one of claims 1 to 10, characterized in that the composition is in the form of emulsion / aqueous dispersion.

-12- Silicone composition capable of crosslinking by polyaddition, to form a coating, water-repellent and non-stick for fibrous or non-fibrous support, characterized: in that it comprises: 1. (II) at least one POS having, per molecule, at least two alkenyl groups (preferably C2-C6) linked to silicon,

^ (1.2) of at least one silicone oil:

• comprising at least one linear hydrogenated PolyOrganoSiloxane (POS) having, per molecule, at least three hydrogen atoms bonded to silicon,

• and with the following average linear formula:

M _α M ' _β D _γ D' _δ with M = (R ') ₃ SiOι ₂

M '= H _a (R') _b SiOι / ₂ , a + b = 3, a = l, 2 or 3, b = 0 to 3

D = (R ² ) ₂ SiO _2/2

D '= HR ³ SiO ₂₂

0 <α <2

0 <β <2

0 <γ

0 <δ

and with:

- t 0 <γ / δ <0.4

—I 20 <(β / δ) x l000 <60.

^ at least one catalyst (II) composed of at least one metal belonging to the platinum group; said catalyst being present at a metal catalyst level being less than or equal to 80 ppm, preferably less than or equal to 65 ppm, and, more preferably still between 30 and 55 ppm.

and in that the POS (s) with the highest viscosity that it contains, has (have) a dynamic viscosity η at 25 ° C less than or equal to 1500 mPa.s.

-13- A composition according to claim 12, as defined in any one of claims 1 to 1.

Support characterized in that it comprises at least one non-stick coating obtained:

"according to the use according to any one of claims 1 to 11," and / or from a composition according to claim 12 or 13.