WO2000060010A1

WO2000060010A1 - Adhesion promoter for a silicone composition

Info

Publication number: WO2000060010A1
Application number: PCT/FR2000/000785
Authority: WO
Inventors: Alain Pouchelon
Original assignee: Rhodia Chimie
Priority date: 1999-03-30
Filing date: 2000-03-29
Publication date: 2000-10-12
Also published as: AU3662000A; FR2791693A1; EP1171526A1; FR2791693B1; CA2364614A1; JP2002541296A

Abstract

An adhesion promoter comprising a pair of compounds selected from the groups of pairs consisting of: (I) an alkenyl, optionally alkoxyl, organosilane, a monomer or polymer devoid of silicon and having an OH group and an epoxy group; (2I) a polymer devoid of silicon, having an OH group and an ethylenic unsaturation, an epoxy organosilicon compound; (3I) a monomer or polymer, devoid of silicon, having an OH group and an ethylenic unsaturation, a monomer or polymer, devoid of silicon, having an OH group and an epoxy group, and optionallly a metal M chelate and/or a metal alkoxide.

Description

ADHESION PROMOTER ESPECIALLY FOR SILICONE COMPOSITION

The invention relates to new adhesion promoters useful in particular in the field of silicones.

It targets the field of silicone compositions developing adhesion properties. The invention applies in particular to compositions which crosslink by hydrosilylation or cold polyaddition (that is to say at room temperature, but the crosslinking of which can be accelerated, eg by heat) and comprising an adhesion promoter according to the invention

The invention relates more particularly to compositions of this type which are in two-component form, and which crosslink by hydrosilylation or polyaddition to produce an elastomer in a thin layer, usable inter alia as a coating, for example for protection or mechanical reinforcement of different substrates , for example in textile material (eg fibrous, woven, knitted or nonwoven), metal (eg aluminum), plastic materials (eg epoxy resins). It relates in particular to their use for coating woven substrates in the manufacture of air bags for the protection of vehicle occupants.

The invention also relates to compositions of this type which can be used as an adhesive. The silicone composition is intended to be applied at the interface of two solids. The adhesion mechanism results from the crosslinking and hardening of the silicone composition comprising the adhesion promoter. It can be applied to the different types of materials mentioned with regard to coating. In these two applications, one of the essential properties of the silicone elastomer is its adhesion power with respect to its support. Various membership agents or promoters have been proposed in the past.

Thus, EP-A-0 681 014 describes a silicone composition, applicable in particular as an internal "airbag" coating and consisting of the mixture formed of:

(I) at least one polyorganosiloxane having, per molecule, at least two alkenyl groups, C ₂ -Cg bonded to silicon, (II) at least one polyorganosiloxane having, per molecule, at least two hydrogen atoms bonded to silicon,

(III) a catalytically effective amount of at least one catalyst, composed of at least one metal belonging to the platinum group, (IV) an adhesion promoter,

(V) optionally a filler, preferably mineral,

(VI) optionally at least one crosslinking inhibitor,

(VII) and optionally at least one polyorganosiloxane resin,

- in which the adhesion promoter consists exclusively of the at least ternary association of the following ingredients:

(IV.1) at least one alkoxylated organosilane containing, per molecule, at least one C ~ - C ₆ alkenyl group, (IV.2) at least one organosilicon compound comprising at least one epoxy radical, (IV.3) at minus a 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 1 -C alkyl,

M being chosen from the group formed by: Ti, Zr, Ge, Li, Mn, Fe, Al and Mg. The availability of various adhesion promoters in silicone products in general is an important objective for industrialists in the sector.

The applicant therefore set itself the objective of proposing new adhesion promoters making it possible inter alia to ensure the adhesion properties of silicone elastomers, eg those intended for coating substrates of the type described higher or intended to serve as an adhesive.

Another object of the invention is to provide such adhesion promoters which also make it possible to increase the adhesion properties, external and / or internal, that is to say between constituents of the elastomer as regards concerns internal adhesion. A subject of the present invention is therefore an adhesion promoter comprising a pair of compounds chosen from the group of couples consisting of:

(0 - an organosilane, optionally alkoxylated, containing, per molecule at least one C2-C6 alkenyl group,

- A monomer or polymer without silicon atom having in its structure at least one OH and at least one epoxy group;

(2i) - a silicon-free polymer, having in its structure at least one OH group and at least one ethylenic unsaturation,

- an organosilicon compound comprising at least one epoxy radical; (3i)

a monomer or polymer without silicon, having in its structure at least one OH group and at least one ethylenic unsaturation,

a monomer or polymer without silicon, having in its structure at least one OH group and at least one epoxy group,

and optionally a metal chelate M and / or metal alkoxide of general formula: M (OJ) n, with n = valence of M and J = linear or branched alkyl at d- C ₈ , M being chosen from the group formed by: Ti, Zr, Ge, Li, Mn, Fe, Al and Mg,

The adhesion promoter thus obtained develops good adhesion properties which can be used both inside the elastomer obtained after crosslinking (internal adhesion between constituents) and outside

(adhesion with a support for example). Preferred applications have been described before.

The polymers are preferably branched polymers and more particularly hyper-branched polymers. These hyper-branched polymers, which include the dendrimers, can be described as being highly branched molecules in three dimensions and having a tree structure. The dendrimers have a high degree of symmetry, while the polymers or macromolecules which are simply called hyperbranched can have a certain degree of asymmetry within their tree structure. We can say that the dendrimer are macromolecules or hyperbranched polymers monodispersed or essentially monodispersed. Hyperbranched or dendrimeric dendritic macromolecules are generally formed of a core or nucleus comprising one or more reaction sites or functions and a certain number of layers of ramifications or generations, possibly one or more spacing layers, and a layer of terminal functions. The higher the number of layers, the more ramifications and therefore of terminal functions. Among the hyperbranched polymers, dendrimers and more particularly polyester-based dendrimers are preferred.

One can for example use a hyperbranched polyester with alkenyl (ethylenic) functions capable of being obtained from a polymer having at least one carboxyl group and m hydroxyl groups, m being an integer greater than or equal to 3, such that in particular 3, 4, 5, 6, 8, 10, 16 or 32. The prepolymer is the condensation product obtained from at least one monomer chosen from the group consisting of di-, tri- and poly-hydroxyfunctional monocarboxylic acids having 2 to 18 carbon atoms. The condensation product obtained constitutes the prepolymer or can be used as an intermediate condensation product in the context of an additional chain extension produced by adding at least one monohydroxyfunctional monocarboxylic acid or an internal ether thereof, namely a lactone having 2 to 24 carbon atoms., The optional addition of a monohydroxyfunctional monocarboxylic acid is carried out by esterification with a molar ratio of intermediate condensation product to monohydroxyfunctional monocarboxylic acid of between 1: 1 and at least 1: m. The prepolymer, namely the condensation product with or without additional chain extension, is functionalized (alkenyl functions) by the addition of at least one monomer or polymer having at least one allylic or acrylic unsaturation. The addition is carried out at a prepolymer molar ratio on allyl or acrylic compound of between 1: 1 and at least 1: m, which leads to the production of a hyperbranched polyester with alkenyl functions having at least one unsaturation allylic or acrylic. For more details, a person skilled in the art can refer to WO-A-9723 539.

One can also use, for example, a hyperbranched polyester with epoxy functions capable of being obtained from a prepolymer having at least one carboxylic group and m hydroxyl groups, m being an integer greater than or equal to 3, such as in particular 3 , 4, 5, 6, 8, 10, 16, 32. The prepolymer is a condensation product obtained by a condensation reaction from at least one monomer chosen from the group consisting of di-, tri- and monocarboxylic acids. poly-hydroxyfunctional having from 2 to 18 carbon atoms. The condensation product obtained constitutes the prepolymer or can be used as an intermediate condensation product for an additional chain extension, this extension being carried out by adding at least one monohydroxyfunctional monocarboxylic acid or an internal ether of this acid, namely a lactone. having 2 to 24 carbon atoms. The optional addition of a monohydroxyfunctional monocarboxylic acid is carried out by esterification at a molar ratio of intermediate condensation product to monohydroxyfunctional monocarboxylic acid of between 1: 1 and at least 1: m. The prepolymer, namely the condensation product with or without chain extension, is functionalized (epoxy functions) by: - reaction between at least one hydroxyl group of the prepolymer and at least one monomer or polymer compound having at least one epoxy group. Suitable compounds are, for example, haloalkyl oxyranes, preferably halomethyl oxyranes such as epichlorohydrin. The reaction is carried out at a prepolymer to monomer or polymer compound molar ratio of between 1: 1 and at least 1: m.

- Or by addition of at least one unsaturated compound having at least one oxidizable unsaturation, this unsaturation being epoxidized by the use of an oxidizing agent, the addition being carried out at a prepolymer molar ratio on unsaturated compound of between 1: 1 and 1: m. For more details, the skilled person can refer to

WO-A-97 23 538. Those skilled in the art can also refer to documents WO-A-96 12 754, WO-A-97 45474 and the book “les dendrimeres”, Club CRIN Hétérochimie, Association ECRIN 1998, 32, bd de Vaugirard 75015 PARIS.

Particularly suitable dendritic polymers are those sold by the company PERSTORP, for example under the name G2 and Boltorn U1 for the dendrimers with allyl functions and Boltorn E1 for the epoxy dendrimers. The monomers are preferably linear or branched monomers. The monomers with unsaturated functions can be mono or polyalcohols with ethylenic unsaturated groups and containing one or more oxygenated heteroatoms. Particularly suitable are aliphatic mono or polyalcohols with ether functions. Among them may be mentioned the following: glycerol monoallyl ether, glycerol diallyl ether, trimethylolethane monoallyl ether, trimethylolethane diallyl ether, trimethylolpropane monoallyl ether, trimethylolpropane diallyl ether, pentaerythritol monoallyl ether, pentaerythritol diallyl ether, pentaerythrit.

Also suitable are allyl ethers of monosaccharides or itols (in English "sugar alcohols"), such as glycosides, galactosides, talitol, mannitol, dulcitol, iditol, sorbitol, arabinitol, xylitol and their mixtures. They can also be combined with the aforementioned aliphatic alcohols. The preferred monomers are:

- trimethylolpropane monoallylether (CAS 682-11-1).

- triallylpentaerythritol (CAS 1471-17-6) or pentaerythritol triallyl ether.

The epoxidized monomers are preferably epoxy or glycidol alcohols comprising the two required functional groups, namely the epoxy or oxyran configuration and the hydroxyl group. Mention may in particular be made of the following compounds: 2,3-epoxy-1-propanol or glycidol, 2,3-epoxybutanol, 3,4-epoxypentanol, 2,3,4, 5-diepoxyhexanol, 2-methyl-3,4 -epoxybutanol,

1-2-epoxyhexanol-8, and mixtures thereof. Those skilled in the art can refer to patents US-A-3,005,832 and US-A-3,041,356 for the description and preparation of such compounds.

Epoxy phenols can also be used. Mention may thus be made, for example, of the polyglycidyl ethers of dihydrophenols such as bisphenol-A or 2,2-bis (4-hydroxyphenol) propane. Advantageously, the skilled person can refer for example at US-A-3,062,840 describing a particular class of epoxy phenols. These are polyhydric, epoxy-substituted polyhydric phenols, comprising an epoxyalkyl chain in which a carbon atom is linked to two hydroxyphenyl substituents. As examples of such bisphenols, the following compounds may be cited: 1,2-epoxy-3,3-bis (hydroxyphenyl) butane, 1,2-epoxy-3,3- bis (hydroxy-phenyl) hexane, 1,2 -epoxy-4,4-bis (hydroxyphenyl) pentane, 1,2-epoxy-3,3-bis (dihydroxyphenyl) propane, 1,2-epoxy-3,3-bis (o-cresyl) propane, 1,2 -epoxy- 3,3-bis (dihydroxyphenyl) butane, and mixtures thereof. They can also be combined with epoxy alcohols. Preferably, when present, the alkoxylated organosilane of the promoter

(4) is more particularly selected from the products of the following general formula (I):

3 3

in which :

- R ¹ , R ² , R ³ are hydrogenated or hydrocarbon radicals identical or different from each other and preferably represent hydrogen, a linear or branched C1-C4 alkyl or a phenyl optionally substituted by at least one alkyl in C1-C3 alkyl, - U is a linear or branched alkylene Ci - C _4, or a divalent group of formula -CO-O-alkylene-, where the alkylene radical is a linear or branched C1-C4 and the free valence of right (in bold) is connected to Si

- R4 and R ⁵ are the same or different radicals and represent a linear or branched C1 - C4 alkyl, - a = 0 to 2, preferably 0 or 1 and more preferably still 0

- b = 0 or 1.

Mention may in particular be made of vinyltrimethoxysilane (VTMO) and γ-methacryloxypropyltrimetoxysilane (MEMO). As regards the organosilicon epoxy compound, it is preferred, when it is present, to choose it - either from the products corresponding to the following general formula (II):

*vs

in which :

• R ⁶ is a linear or branched Cj - C4 alkyl radical,

• R ^ is a linear or branched alkyl radical,

C is equal to 0, 1, 2 or 3, preferably 0 or 1 and, more preferably still 0,

• X is

(III)

\

with

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

Δ d which is equal to 0 or 1,

Δ Rβ, R ⁹ , R10 which are identical or different radicals representing hydrogen or a linear or branched C1-C4 alkyl, hydrogen being more particularly preferred, Δ R ⁸ and R ⁹ or R ¹⁰ can alternately constitute together and with the two carbons carrying the epoxy, an alkyl ring having from 5 to 7 links, - either from the products constituted by epoxyfunctional poiydiorganosiloxanes comprising:

(i) at least one siloxyl unit of formula (IV):

X _p G _q SiO

4 - (p + q)

2 in which:

• X is the radical as defined above for formula (II) • G is a monovalent hydrocarbon group, free from any adverse action on the activity of the catalyst and preferably chosen from alkyl groups having from 1 to 8 carbon atoms included, optionally substituted with at least one halogen atom, advantageously from methyl, ethyl, propyl and 3,3,3-trifluoropropyl groups and also from aryl groups and advantageously from xylyl radicals and tolyl and phenyl,

• p = 1 or 2,

• q = 0, 1 or 2,

• p + q = 1, 2 or 3, and (2i) optionally at least one siloxyl unit of formula (V):

^G r Si0 ₄ _ _r

in which G has the same meaning as above and r has a value between 0 and 3, for example between 1 and 3.

These compounds are preferably epoxyalkoxymonosilanes.

Examples of such compounds that may be mentioned: - 3-glycidoxypropyltrimethoxysilane (GLYMO) - or 3,4-epoxycyclohexylethyltrimethoxysilane.

As regards the compound of chelate or aloxide type, it may consist of, or comprise a metallic chelate. The chosen metal M can thus include one or more ligands such as those derived in particular from a beta-diketone, such as for example acetylacetone. This compound 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 OJ alkoxy radicals can be replaced by one or more ligands constituting a chelate, such as for example an acetylacetonate ligand.

The preferred compounds are those in which the metal M is chosen from the following list: Ti, Zr, Ge, Mn, Al. It will be noted that titanium is more particularly preferred.

Concrete examples of compounds which are very suitable are those in the structure of which the metal M is chosen from the list: Ti, Zr, Ge, Mn, and Al and is associated:

- in the case of a chelate: to ligands of acetylacetonate type - in the case of an alkoxide: to n-propoxy or n-butoxy radicals.

Quantitatively, it can be specified that the weight proportions between the various constituents of the adhesion promoter, expressed in percentages by weight relative to the total of the three, are as follows:

- unsaturated compound> 10% - epoxy compound <90%

- chelate, alkoxide, silicate, polysilicate: from 0 to 25%.

Preferred adhesion promoters of types (i) and (2i) are preferred.

The most preferred adhesion promoters are those of type (2i) comprising an alkenyl-functional dendrimer, an epoxy-functional organosilicon compound and a metal chelate and / or alkoxide. The organosilicon compound is then preferably GLYMO or alternatively 3,4-epoxycyclohexyl-ethyltrimethoxysilane.

Other types of promoters of interest are the following:

- VTMO or MEMO + epoxy dendrimer + metal chelate or alkoxide - Alkenyl dendrimer + epoxy dendrimer + optionally chelate or metal alkoxide or ethyl silicate.

The present invention also relates to silicone compositions of the type of those which can be vulcanized cold (EVF), comprising: (1) at least one polyorganosiloxane having, per molecule, at least two alkenyl groups, in C2-C6 bonded to silicon,

(2) at least one polyorganosiloxane having, per molecule, at least two hydrogen atoms bonded to silicon, (3) a catalytically effective amount of at least one catalyst, based on at least one metal belonging to the platinum group ,

(4) an adhesion promoter according to the invention,

(5) possibly a charge,

(6) optionally a polyorganosiloxane qualified as an extender and having terminal siloxyl units with hydrogen functions,

(7) possibly a neutralizer,

(8) optionally a crosslinking inhibitor and / or other additive (s) in use in the type of composition targeted,

(9) optionally a polyorganosiloxane resin. Those skilled in the art are well aware that when component (1) has 2 alkenyl groups per molecule, component (2) must have at least 3 hydrogen atoms per molecule. Conversely, when component (2) has 2 hydrogen atoms per molecule, component (1) has at least 3 alkenyl groups per molecule. Advantageously, the adhesion promoter is present at a rate of 0.1 to

10, preferably 0.5 to 5 and more preferably still 1 to 3% by weight relative to all of the constituents of the composition.

The polyorganosiloxane (1) is by weight one of the essential constituents of the composition according to the invention. Advantageously, it is a product comprising

(i) siloxy units of formula:

W ⁰ 4 - (a ₊ b)

^ (1.1) in which:

T 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, optionally substituted with at least one halogen atom, advantageously, among the methyl, ethyl, propyl and 3,3,3-trifluoropropyl groups and also among the aryl groups and, advantageously, among the xylyl, tolyl and phenyl radicals, a is 1 or 2 , b is 0, 1 or 2 and a + b is between 1 and 3, preferably between 2 and 3, and (2i) optionally other siloxy units of formula:

Z _c SiO 4 - c

(1.2)

wherein Z has the same meaning as above and c has a value between 0 and 3, preferably between 2 and 3. It is advantageous that this polydiorganosiloxane has a viscosity between 100 and 200,000 mPa.s. It is preferably from 500 to 5000 mPa.s in the case where a reinforcing filler is used, in particular a reinforcing filler treated in situ. In the absence of such a load, it preferably becomes between 10,000 and 200,000 mPa.s. Of course, in the case of mixing several oils (1) of different viscosity, the viscosity of the mixture is taken into account.

All the viscosities in question here correspond to a quantity of dynamic viscosity which is measured, in a manner known per se, at 25 ° C.

The polyorganosiloxane (1) can be formed only of units of formula (1.1) or can additionally contain units of formula (1.2).

Z is generally chosen from methyl, ethyl and phenyl radicals, at least 60 mol% (or by number) of the radicals Z being methyl radicals.

Examples of siloxyl units of formula (1.1) are the vinyldimethylsiloxyl unit, the vinylphenylmethylsiloxyl unit, the vinylmethylsiloxyl unit and the vinylsiloxyl unit.

Examples of siloxyl units of formula (1.2) are the S1O4 / 2, dimethylsiloxyl, methylphenylsiloxyl, diphenylsiloxyl, methylsiloxyl and phenylsiloxyl units. Examples of polyorganosiloxanes (1) are linear and cyclic compounds such as: dimethylpolysiloxanes with dimethylvinylsilyl ends, (methylvinyl) (dimethyl) polysiloxanes with trimethylsilyl ends, copolymers (methylvinyl) (dimethyl) polysiloxanes with dimethylvinylsilyl ends; cyclic methylvinylpolysiloxanes.

The polyorganosiloxane (2) is preferably of the type of those comprising: (i) siloxy units of formula (2.1):

H ¹ d_, L ^L e-.S- iO - ( ^{d + e} ) 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, advantageously substituted by at least one halogen atom, advantageously , among the methyl, ethyl, propyl and 3,3,3-trifluoropropyl groups and also among the aryl groups and, advantageously, among the xylyl, tolyl and phenyl radicals, d is 1 or 2, e is 0, 1 or 2 , d + a a value between 1 and 3, preferably between 2 and 3, and (2i) optionally other siloxy units of average formula (2.2):

SiO S. ^ 2

in which L has the same meaning as above and g has a value between 0 and 3, preferably between 2 and 3. The dynamic viscosity of this polyorganosiloxane (2) is at least equal to

10 mPa.s and, preferably, it is between 20 and 1000 mPa.s.

The polyorganosiloxane (2) can be formed solely of units of formula (2.1) or additionally comprise units of formula (2.2). The polyorganosiloxane (2) can have a linear, branched, cyclic or network structure.

Group L has the same meaning as group Z above. Examples of units of formula (2.1) are: H (CH ₃ ) 2SiOι / ₂ , HCH ₃ Siθ2 / 2- H (C ₆ H ₅ ) Siθ2 / 2

The examples of units of formula (2.2) are the same as those given above for the units of formula (1.2).

Examples of polyorganosiloxane (2) are linear and cyclic compounds such as: - dimethylpolysiloxanes with hydrogenodimethylsilyl ends,

- copolymers with (dimethyl) (hydrogenomethyl) polysiloxane units with trimethylsilyl ends,

- copolymers with (dimethyl) (hydrogenomethyl) polysiloxane units with hydrogenodimethylsilyl ends, - hydrogenomethylpolysiloxanes with trimethylsilyl ends,

- cyclic hydrogenomethylpolysiloxanes.

The ratio of the number of hydrogen atoms bonded to silicon in the polyorganosiloxane (2) over the total number of alkenyl unsaturated groups in the polyorganosiloxane (1) is between 1 and 5, preferably between 1 and 2. The catalysts ( 3) are also well known. The platinum and rhodium compounds 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 patents US-A-3419 593,

US-A-3 715 334, US-A-3 377432 and US-A-3 814 730. The generally preferred catalyst is based on platinum. In this case, the quantity by weight of catalyst (3), calculated by weight of platinum-metal, is generally between 2 and 400 ppm, preferably between 5 and 50 ppm based on the total weight of the polyorganosiloxanes (1) and (2 ).

Advantageously, the silicone composition according to the invention can also comprise at least one retarder for the addition reaction or crosslinking inhibitor (8), chosen from the following compounds: polyorganosiloxanes substituted with at least one alkenyl which may optionally be in cyclic form, tetramethylvinyltetrasiloxane being particularly preferred,

- pyridine - organic phosphines and phosphites,

- unsaturated amides

- alkylated 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 blockers, have the formula:

R '- (R ") C (OH) - C = CH formula in which,

- R 'is a linear or branched alkyl radical, or a phenyl radical; - R "is H or a linear or branched alkyl radical, or a phenyl radical; the radicals R ', R" and the carbon atom located at α of the triple bond 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; - diphenyl-1, 1 propyne-2 ol-1;

- 3-ethyl-6-ethyl nonyne-1 ol-3;

- 2-methyl-butyne-3 ol-2;

- 3-methyl-pentadecyne-1 ol-3.

These α-acetylenic alcohols are commercial products. Such a retarder is present at a maximum of 5,000 ppm, preferably at a rate of 100 to 2,000 ppm relative to the total weight of the organopolysiloxanes (1) and (2). The filler (5) can be a reinforcing or non-reinforcing filler, or a combination of the two, depending on the properties sought.

The reinforcing filler is preferably a siliceous filler.

The reinforcing siliceous fillers are chosen from colloidal silicas, combustion and precipitation silica powders or their mixtures.

These powders have an average particle size generally close to or less than 0.1 μm and a BET specific surface greater than 50 m ² / g, preferably between 50 and 400 m ² / g, in particular between 150 and 350 m ² / g .

Among the complementary non-reinforcing fillers, mention may in particular be made of diatomaceous earths, calcium carbonate, ground quartz and ground zirconium oxide or zirconia. These fillers have a particle size generally between 0.001 and 300 μm and a BET surface area of less than 100 m ² / g.

Other additional fillers are for example carbon black, titanium dioxide, aluminum oxide, hydrated alumina, expanded vermiculite, unexpanded vermiculite, zinc oxide, mica, talc , iron oxide, barium sulfate and slaked lime. Other additional charges can be microspheric charges.

The reinforcing silicas can preferably be incorporated as such or after having been treated with organosilicon compounds usually used for this use. Among these compounds are methylpolysiloxanes such as hexamethyldisiloxane, octamethylcyclotetrasiloxane, methylpolysilazanes such as hexamethyldisilazane, hexamethylcyclotrisilazane, chlorosilanes such as dimethyldichlorosilane dimethylchlorosilane, trimethyl dimethyldimethoxysilane, dimethylvinylethoxysilane, trimethylmethoxysilane. During this treatment, the silanes can increase their starting weight up to a rate of 20%, preferably about 10%.

Preferably the siliceous filler is treated in situ. By in situ treatment of the siliceous filler is preferably meant the bringing together of the filler and the compatibilizing agent in the presence of at least one portion of polyorganosiloxane silicone oil (1). In a particularly preferred manner, the procedure is as described in WO-A-98 58997 to which a person skilled in the art may refer for more details. In a particularly preferred manner, this essentially consists in introducing compatibilization agent (CA) in two stages into the preparation medium:

On the one hand, before and / or substantially simultaneously with the presence of at least part of the silicone oil used with at least a portion of the siliceous filler used, this introduction of AC (portion 1 ) operating in one or more times and corresponding to a proportion less than or equal to 8%, preferably 5% and, more preferably still, 3% by dry weight relative to the total load;

• and on the other hand (portion 2), after this placing in the presence of silicone oil / filler.

The compatibilization agent for portion 1 is thus chosen from molecules which satisfy at least two criteria:

- present a strong interaction with the silica at the level of its hydrogen bonds with itself, and with the surrounding silicone oil - be itself, or its degradation products, easily removed from the final mixture by heating under vacuum or under current gaseous, and low molecular weight compounds are therefore preferred. By globally equivalent amount is meant compliance with the order of magnitude of the molar quantities of AC with respect to the hydrogen bonds. The agent of the portion 1 could be for example:

- a silazane, preferably a disilazane, or mixtures thereof, hexamethyldisilazane (HMDZ) being the preferred silazane and which can be combined with divinyltetramethyldisilazane

- a di- or preferably mono-functional hydroxylated siloxane - an amine such as ammonia or a low molecular weight alkylamine such as diethylamine

- a low molecular weight organic acid such as formic or acetic acids, - And is preferably implemented in the presence of water.

The compatibilizers of the portion 2 can be chosen from the various silazanes and disilazanes encountered above, taken alone or as a mixture with one another, preferably from disilazanes, hexamethyldisilazane associated or not with divinyltetramethyldisilazane being particularly preferred.

The silicic reinforcing filler represents from 10 to 50% by weight of the suspension obtained. In practice, this charge is of the order of 25 ± 10%.

Advantageously, the proportion of compatibilization agent introduced initially is at most equal to 8% of the reinforcing filler (and for example between 1 and 3% of the reinforcing filler, preferably between 1 and 2%). Furthermore, it can be indicated that the total amount of agent AC is preferably between 5 and 30% of the silicic filler, preferably between

10 and 20%.

As a variant, it is possible to use the compatibilization methods of the prior art which provide for early treatment with silazane (eg FR-A-2 320 324) or late treatment (eg EP-A-462 032) while knowing, however, that depending on the silicas used, their use will generally not give the best results in terms of mechanical properties, in particular extensibility, obtained by a two-stage treatment in accordance with the invention. In the case where the in situ treatment leads to a basic pH, a neutralizer (7) can be added such as for example weak acids (eg acetic acid and buffered phosphoric acid). It will be noted that this neutralization can be advantageously obtained by the incorporation of charges of an acidic nature such as ground quartz. The microspheric fillers are preferably expandable organic microspheres comprising, as is known per se, a polymer wall containing a liquid or a gas. These microspheres are caused to expand by heating them beyond the softening point of the polymer and to a temperature sufficient to vaporize the liquid or properly expand the gas, which may for example be an alkane such as isobutane or isopentane. The wall can consist, as is known per se, of polymers or copolymers, for example prepared from monomers vinyl chloride, vinylidene chloride, acrylonitrile, methyl methacrylate or styrene or mixtures of polymers and / or copolymers, for example in particular of acrylonitrile / methacrylonitrile copolymer, acrylonitrile / vinylidene chloride copolymer. See in particular US-A-3,615,972.

They can be incorporated into the composition either in the expanded state or before their expansion, which can be induced, by appropriate heating, during the crosslinking of the composition.

It may be advantageous for the microspheres to be treated on the surface as is known per se, in order to promote its dispersion in the composition; they may in particular be expandable or expanded microspheres having an inorganic coating, for example silica or metal salts or hydroxides such as Ca, Mg, Ba, Fe, Zn, Ni, Mn, as described for example in EP- A-486 080, or carbonates, for example calcium carbonate.

As a preferred example, the microspheres sold under the name Duality® by UCB-chemicals are used.

Before their expansion, the microspheres will preferably have a diameter between 3 and 50 μm, more particularly between 5 and 30 μm.

We will also look for a diameter after expansion (in situ or original) of between 10 and 150, in particular between 20 and 100 μm. These microspheres will be present in particular at a rate of 1 to 30% by weight, preferably from 2 to 10% and more preferably more than 3 or 4%, by weight relative to the total composition.

The polyaddition composition may also comprise an extender polyorganosiloxane (6) having, per molecule, two siloxy groups carrying a hydrogen atom linked to the silicon. These polyorganosiloxane extenders are perfectly known to those skilled in the art.

The polyorganosiloxane extender (6) has terminal siloxyl units

HR ° ₂ SiO 1/2

with . R ° identical or different between them and corresponding to a linear or branched alkyl group in CrC ₆ and / or substituted or unsubstituted aryl, R ° being preferably CH ₃ .

Note that the rest of the molecule is a polydiorganosiloxane, preferably a polydimethylsiloxane.

By way of example, mention may be made of poiy (dimethylsiloxy) -α, ω- (dimethylhydrogenosiloxy).

According to a particular form of the invention, the silicone composition combines a reinforcing filler (5) treated in situ, preferably according to WO-A-98 58997, and an extender polyorganosiloxane (6). In such a composition, if the alkoxylated organosilane is present, b is preferably 1. This type of composition is particularly useful for coating substrates, in particular fibrous substrates, for example for the production of "airbags".

The composition according to the invention may also comprise at least one polyorganosiloxane resin (9) comprising at least one alkenyl residue in its structure, and this resin has a content by weight of alkenyl group (s) of between 0, 1 and 20% by weight and preferably between 0.2 and 10% by weight.

These resins are well known and commercially available branched organopolysiloxane oligomers or polymers. They are in the form of solutions, preferably siloxane. They have, in their structure, at least two different patterns chosen from those of formula RsSiOo.s

(motil M) 1, R ₂ SiO (motif D) 1, RSiOι, ₅ (motif T) and SiO ₂ (motif Q), at least one of these motifs being a motif T or Q.

The radicals R are identical or different and are chosen from linear or branched C1-C6 alkyl radicals, C2-C4 alkenyl radicals, phenyl, 3,3,3-propyl trrfluoro. Examples that may be mentioned: as alkyl radicals R, methyl, ethyl, isopropyl, tert-butyl and n-hexyl radicals, and as alkenyl radicals R, vinyl radicals.

It should be understood that in the resins (9) of the aforementioned type, part of the radicals R are alkenyl radicals.

As examples of branched organopolysiloxane oligomers or polymers, mention may be made of MQ resins, MDQ resins, TD resins and MDT resins, the alkenyl functions being able to be carried by the units M, D and / or T. As an example of resins which are particularly suitable, mention may be made of vinylated MDQ resins having a weight content of vinyl group of between 0.2 and 10% by weight.

This compound (9) has in particular the function of increasing the mechanical resistance of the elastomer, eg of the silicone elastomer coating, as well as its adhesion, eg within the framework of coating the faces of a synthetic fabric (for example in polyamide), for example in the manufacture of "airbags". When it is present, this structural resin is advantageously present in a concentration of between 10 and 70% by weight relative to all the constituents of the composition, preferably between 30 and 60% by weight and, more preferably still , between 40 and 60% by weight.

In a particularly preferred manner, the polyorganosiloxane resin (9) will comprise at least 2% by weight of SiO _{2 units} (Q units), in particular from 4 to 14%, preferably from 5% to 12%. The incorporation of these resins makes it possible, if desired, to dispense with filler and in particular with reinforcing siliceous filler. The advantage is then to be able to apply very thin layers of elastomer, for example with a deposited weight less than or equal to 30 g / m ² .

According to another of its aspects, the present invention relates to a two-component precursor system of this preferred silicone composition described above. Such a precursor system is in two separate parts A and B, intended to be mixed to form the composition, one of these parts A or B comprising the catalyst (3) and uηe only species (1) or (2) of polyorganosiloxane. Another characteristic of this precursor system is that its part A or B containing the polyorganosiloxane (2) is free of compounds of the chelate or metal alkoxide type of the promoter (4) and that its part A or B including the unsaturated compound of the promoter (4) ) does not include the catalyst (3); when it is present, the filler (5) treated in situ is present in the part or parts A and B which contain the polyorganosiloxane (1). Determining and optimizing the two parts A and B to avoid bringing into one of the parts species capable of reacting together is part of the normal capacity of those skilled in the art. Once mixed together, the parts A and B form a ready-to-use silicone composition, which can be applied to the support by any suitable coating means (for example doctor blade, cylinder, screen printing, etc. ). Although the crosslinking can be carried out cold (that is to say at a temperature close to the ambient temperature close to 20 ° C.), the compounds according to the invention are crosslinked by suitable means, in particular thermally and / or by electromagnetic radiation (radiation of accelerated electrons or "electron beam"), and / or infrared.

Another subject of the invention is the use of the adhesion promoter according to the invention in the preparation of silicone compositions, in particular those which can be used for coating various substrates such as those described above and / or for the use of adhesive. .

According to a first preferred embodiment of the invention, the silicone compositions comprising the above promoter can be used in particular for coating or coating, woven, knitted or non-woven fibrous supports, and preferably woven, knitted supports or nonwovens made of conventional or technical synthetic fibers, advantageously polyester or polyamide and glass fabrics.

The invention relates more particularly to the coating or coating of at least one of the faces (interior and / or exterior) of the flexible support material (polyamide fabric for example) useful for the manufacture by sewing of inflatable bags for personal protection occupants of vehicles, in the event of an impact.

According to a second preferred method, the compositions according to the invention can also be used as an adhesive, in particular for textile, metallic or plastic parts.

The present invention also relates to the use of these compositions or of their precursor systems as described above, for the coating or coating of fibrous supports as described above or for adhesion. Finally, the adhesion promoters can also be used in the silicone crosslinkable compositions hot known under the name EVC and in particular those crosslinking by polyaddition or EVCs with peroxide. The invention also relates to the use of the monomers and polymers described above for the production of adhesion promoters and for the preparation of silicone compositions.

The invention will now be described in more detail using embodiments and then by way of nonlimiting examples.

EXAMPLES

The polymer tested is a dendritic polymer of the ester type. It is characterized by:

• a basic 4-star star heart

• level 2 generation

• an allylic functionality

• allyl functionality rate: 2.06 mmol / g 14.4 mole allyl / mole G2

• residual hydroxyl functionality

• rate of residual OH functionality: 0.11 mmol / g

0.8 mole hydroxy / mole G2

This dendritic polymer hereinafter called G2 is accessible from the company PERSTORP.

EXAMPLE 1: REFERENCE COMPOSITION 1

It is a two-component silicone composition, the composition of which is particularly suitable for bonding.

First of all, a suspension called a premix is prepared by mixing in a reactor at room temperature:

- 51, 7 parts of MM ^V structure resin ^| DD ^{V |} Q containing 0.9% by weight of vinyl groups (Vi) and consisting of: 21% by weight of units

(CH ₃ ) ₃ SiO _0.5 ; 0.2% by weight of (CH ₃ ) 2ViSiOo, s units; 67.8% by weight of (CH ₃ ) ₂ SiO units; 3% by weight of (CH ₃ ) ViSiO units; 8% by weight of SiO _{2 units} . - 15 parts by weight of a polydimethylsiloxane (PDMS) blocked by (CH ₃ ) ₂ ViSiOo.5 units having a viscosity of 10,000 mPa.s and containing 0.005 SiVi functions per 100 g of oil

- 33.3 parts by weight of a ground silica with an average particle size of approximately 2 μm.

This premix is used for the preparation of parts A and B of the bicomponent Part A of the bicomponent n ° 1

In a reactor at room temperature: 99.3 parts by weight of premix are mixed

- 0.7 part by weight of butyl orthotitanate

- 0.004 part by weight of platinum metal in the form of a metal complex known as the Karstedt catalyst

Part B of the bicomponent n ° 1 In a reactor at room temperature, one mixes:

- 90.3 parts by weight of premix

- 4.52 parts by weight of a poly (dimethyl) (hydrogen methyl) siloxane blocked by (CH ₃ ) ₂ HSiO _{0.5 units} having a viscosity of 25 mPa.s and containing a total of 0.7 SiH function per 100 g of oil - 0.04 parts by weight of EthynylCycloHexanol

- 1.8 parts by weight of vinyl trimethoxy silane (VTMO)

- 1.8 parts by weight of 3-glycidoxypropyltrimethoxysilane (GLYMO)

- 0.2 part by weight of a coloring base.

The bicomponent is obtained by mixing at room temperature 100 parts of A no.1 and 100 parts of B no.1. Composition C1 is thus obtained.

EXAMPLE 2: REFERENCE COMPOSITION 2

It is the previous two-component silicone composition to which the unsaturated silane was removed from the adhesion promoter. The same suspension called the premix and the same part A as described in Example 1 are used.

Part A of Two Component # 2 This is Part A of Two Component # 1

Part B of two-component n ° 2

In a reactor at room temperature:

- 90.3 parts by weight of premix - 4.52 parts by weight of a poly (dimethyl) (hydrogenomethyl) siloxane blocked by (CH ₃ ) ₂ HSiO ₀ , s units having a viscosity of 25 mPa.s and containing a total of 0.7 SiH function per 100 g of oil.

- 0.04 part by weight of EthylnylCycloHexanol

- 1.8 parts by weight of 3-glycidoxypropyltrimethoxsilane (GLYMO) - 0.2 parts by weight of a coloring base

The bicomponent is obtained by mixing at room temperature 100 parts of A no. 2 and 100 parts of B no. 2. Composition C2 is thus obtained.

EXAMPLE 3 COMPOSITION ACCORDING TO THE INVENTION

The composition is that of the reference two-component silicone preparation to which the dendritic polymer has been added.

The same suspension called the premix and the same part A as described in Example 1 are used.

Part A of bicomponent n ° 3

This is part A of bicomponent n ° 1

Part B of two-component n ° 3

In a reactor at room temperature:

- 90.3 parts by weight of premix - 4.52 parts by weight of a poly (dimethyl) (hydrogen methyl) siloxane blocked by (CH ₃ ) ₂ HSiOo units, s having a viscosity of 25 mPa.s and containing a total of 0.7 SiH function per 100g d 'oil

- 0.04 part by weight of EthynylCycloHexanol

- 3.6 parts by weight of the dentritic polymer with allylic functions (G2)

- 1.8 parts by weight of 3-glycidoxypropyltrimethoxysilane (GLYMO)

- 0.2 part by weight of a coloring base.

The bicomponent is obtained by mixing at room temperature 100 parts of A no.3 and 100 parts of B no.3. Composition 03 is thus obtained.

PERFORMANCE FOR EXAMPLES 1 TO 3

Adhesive performance is assessed by a peel test. For this, a layer of controlled thickness of the bicomponent is deposited between two substrates and crosslinking of the bicomponent is carried out.

After cooling, the force necessary to cause the separation of the substrates is measured by means of a traction machine provided with a device for recording the force exerted.

The substrate S used for these assessments is a polyamide 66 fabric of 470 dtex, woven in 18x18 strands.

The following results were recorded: Table 1

EXAMPLE 4 Products tested

The tested products are described below:

Boltorn U1 is a dendrimer of mass approximately 8000 which carries approximately 14 allyl functions.

Boltorn E1 is a dendrimer of mass approximately 10500 which carries approximately 11 epoxy functions.

Polyol PS50 is an ethoxylated pentaerythritol of mass approximately 350 which carries 4 hydroxy functions but no unsaturated function (for comparison). These products are available from PERSTORP

The composition is that of the standard two-component silicone preparation of Example 1 in which one of the promoter silanes has been substituted with one of the products tested (dendritic polymers). Type 1 promoter additives (unsaturated function) replace VTMO; type 2 promoter additives (with epoxy function) replace GLYMO.

Part A of two-component # 4 to 7 This is part A of two-component # 1

Part B of bicomponents n ° 4 to 7

In a reactor at room temperature:

- 90.3 parts by weight of premix

- 4.52 parts by weight of a poly (dimethyl) (hydrogen methyl) siloxane blocked by (CH ₃ ) 2HSiOo, 5 units having a viscosity of 25 mPa.s and containing a total of 0.7 SiH function per 100 g of oil

- 0.04 part by weight of EthynylCycloHexanol

- 1.8 parts by weight of VTMO or one of the type 1 promoter additives (see Table 2) - 1.8 parts by weight of GLYMO or one of the type promoter additives

2 (see table 2)

- 0.2 part by weight of a coloring base. The bicomponent is obtained by mixing at room temperature 100 parts of A no. 4 to 7 and 100 parts of B no. 4 to 7. This gives compositions 04 to C9. PERFORMANCES

The adhesive performance is evaluated as before by the peel test.

The applied surface weights are always of the order of 120 g / m2.

The following results were recorded: Table 2:

COMMENTS ON THE EXAMPLES The results presented demonstrate the equivalence of the performances according to compositions C1 and C3 and the advantage compared to composition 02 which does not contain an unsaturated promoter.

Example 4 demonstrates the capacity of the polyfunctional dendrimers in terms of self-adhesion provided to the compositions which contain them. We also observe the need for dual function of these molecules for this use.

It is also known that the adhesive power of these compositions is not limited to the area of bonding of textiles. This is how they also allow bonding to metal, especially aluminum and plastics, especially epoxy resins.

It has also been noted, without being limiting, that the G2 dendrimer introduced into a silicone rubber which can be crosslinked when hot under the action of a peroxide sticks to the mold in which it is shaped. This further demonstrates the potential of these products to impart a self-adhesive character to the compositions of silicone elastomers.

Claims

1.- Adhesion promoter comprising a pair of compounds chosen from the group of couples consisting of: (i)

an organosilane, optionally alkoxylated, containing, per molecule at least one C2-C6 alkenyl group,

- A monomer or polymer without silicon atom having in its structure at least one OH and at least one epoxy group; (2i)

- a silicon-free polymer, having in its structure at least one OH group and at least one ethylenic unsaturation,

- an organosilicon compound comprising at least one epoxy radical; (3i) - a monomer or polymer without silicon, having in its structure at least one OH group and at least one ethylenic unsaturation,

and optionally a metal chelate M and / or metal alkoxide of general formula: M (OJ) n, with n = valence of M and J = linear or branched d-C ₈ alkyl, M being chosen from the group formed by: Ti, Zr, Ge, Li, Mn, Fe, Al and Mg,

2.- Adhesion promoter according to claim 1, characterized in that the polymers are chosen from the group consisting of branched polymers and hyper-branched polymers.

3. Adhesion promoter according to claim 2, characterized in that the hyperamified polymers are dendrimers.

4. Adhesion promoter according to claim 3, characterized in that the dendrimers are based on polyesters.

5. Adhesion promoter according to claim 1, characterized in that the monomers are linear or branched monomers.

6.- Adhesion promoter according to claim 5, characterized in that the monomers are chosen from the group consisting of mono and polyalcohols with unsaturated ethylenic groups and containing one or more oxygenated heteroatoms, allylethers of monosaccharides or itols and their mixtures .

7. Adhesion promoter according to claim 6, characterized in that the alcohols are aliphatic mono or polyalcohols with ether functions.

8. Adhesion promoter according to claim 5, characterized in that the monomers are chosen from the group consisting of: glycerol monoallyl ether, glycerol diallyl ether, trimethylolethane monoallyl ether, trimethylolethane diallyl ether, trimethylopropane monoally ether, trimethylolpropane diallyl ether, pentaerythritol monoallyl ether pentaerythritol diallyl ether, pentaerythritol trially ether, glycosides, galactosides, talitol, mannitol, dulcitol, iditol, sobitol, arabinitol, xylitol and their mixtures.

9. Adhesion promoter according to claim 5, characterized in that the monomers are chosen from the group consisting of: trimethylopropane monoallylether, triallylpentaerythritol.

10.- Adhesion promoter according to claim 5, characterized in that the monomers are chosen from the group consisting of epoxy alcohols and epoxy phenols.

11. An adhesion promoter according to claim 10, characterized in that they are chosen from the group consisting of: 2,3-epoxy-1-propanol or glycidol, 2,3-epoxybutanol, 3,4-epoxypentanol, 2,3,4,5-diepoxyhexanol, 2-methyl-3,4-epoxybutanol, 1 -2-epoxyhexanol-8, 3,4-epoxyhexanol (?), 2,3-epoxypentanol (?), 2,2- bis (4-hydroxyphenol) propane, 1,2-epoxy-3,3-bis (hydroxyphenyl) butane, 1,2-epoxy-3,3-bis (hydroxy-phenyl) hexane, 1,2-epoxy-4, 4-bis (hydroxyphenyl) - pentane, 1,2-epoxy-3,3-bis (dihydroxyphenyl) propane, 1,2-epoxy-3,3-bis (o-cresyl) - propane, 1,2-epoxy-3,3-bis (dihydroxyphenyl ) butane, and mixtures thereof.

12.-Adhesion promoter according to claim 1, characterized in that it comprises the pair (3i) and an alkyl silicate or polysilicate.

13.-Silicone composition of the type of those which can be vulcanized cold, comprising:

(1) at least one polyorganosiloxane having, per molecule, at least two alkenyl groups, C 2 -C 6 bonded to silicon,

(2) at least one polyorganosiloxane having, per molecule, at least two hydrogen atoms bonded to silicon,

(3) a catalytically effective amount of at least one catalyst, based on at least one metal belonging to the platinum group, (4) an adhesion promoter characterized in that it comprises an adhesion promoter according to l any of claims 1 to 12.

14. Composition according to Claim 13, characterized in that it also comprises a compound chosen from the group consisting of:

(5) a charge,

(6) a polyorganosiloxane qualified as an extender and having terminal siloxyl units with hydrogen functions,

(7) a neutralizer, (8) a crosslinking inhibitor,

(9) expanded or expandable inorganic hollow microspheric fillers,

(10) a polyorganosiloxane resin, and mixtures thereof.

15. -Use of an adhesion promoter according to any one of claims 1 to 12, for the preparation of silicone compositions having adhesion properties.

16. Use of an adhesion promoter according to claim 15, for the preparation of a silicone composition crosslinking at room temperature by hydrosilylation or polyaddition.

17. Use of an adhesion promoter according to claim 15 or 16, for the preparation of silicone compositions intended for coating substrates.

18. Use of an adhesion promoter according to claim 15 or 16, for the preparation of silicone compositions intended to serve as an adhesive.