Silicone composition crosslinkable into elastomer by hydrosilylation, in the presence of carbene-based metal catalysts, and catalysts

ES 2 325 985 T3

DESCRIPTION

Composition of silicone crosslinkable in elastomer by hydrosilylation, in the presence of metal catalysts based on carbenes, and catalysts of this type.

The invention concerns the catalysis of hydrosilylation reactions and particularly hydrosilylation of ethylenically and / or acetylenically unsaturated compounds (for example olefins or acetylenic derivatives), in particular those involving polyorganosiloxanes (POS) bearing Si-H and POS residues bearing Si residues (ethylenic or acetylenic unsaturation).

More precisely, the invention concerns silicone compositions that can be crosslinked -preferably elastomers- by hydrosilylation of at least one PolyOrganoSiloxane (POS) -A carrier of ethylenic and / or acetylenic unsaturation (s), with the help of at least one polyorganohydrogenosiloxane -B-, in the presence of a metallic catalyst -C- and optionally comprising at least one inhibitor -D- of the hydrosilylation reaction.

Classically, the hydrosilylation reactions that allow the crosslinking of silicones are catalyzed by platinum catalysts (US 2823218, US 2970150). In practice, to this day, most of the industrial hydrosilylation reactions are catalyzed by the Karstedt solution, which is made up of platinum complexes with oxidation degree 0. The ideal general formula of the Karstedt complex is Pt₂ (tetramethyldivinylsiloxane)₃:

<img file="ES2325985T3_D0001.tif" />

where Me represents methyl.

The Karstedt complex is prepared by contacting 1,3-divinyltetramethyldisiloxane with chloroplatinic acid (H₂PtCl₆), in the presence of NaHCO₃ and of a hydroalcoholic solvent (isopropanol).

This conventional catalyst and its preparation are described in US patent 3775452.

The great catalytic activity of this type of catalyst, even at room temperature, is a major drawback in the context of its use in polyaddition EVCs, since the elastomer crosslinking begins as soon as all of the components come into contact.

Another drawback of this catalyst resides in a possible instability of the catalyst during the reaction: it has been observed the precipitation of metallic platinum and the formation of insoluble colloids in the reaction medium: this instability of the catalyst in the reaction medium has the effect of reducing catalytic activity. Furthermore, sometimes colored products result, which are little appreciated by the user.

Another important drawback of the Karstedt catalyst is the concomitant formation of by-products of the hydrosilylation reaction: together with the hydrosilylation products, the products resulting from olefinic double bond isomerization reactions and / or hydrogenation reactions are isolated.

Unpublished patent application FR 99 15432 dated 12/07/1999 discloses metal complexes useful as hydrosilylation catalysts, of the formula:

<img file="ES2325985T3_D0002.tif" />

ES 2 325 985 T3 in which:

R₃ represents a hydrogen atom; an alkyl group (C₁-C₈); or a cycloalkyl group (C₃-C₈) optionally substituted with alkyl (C₁-C₄);

T₁ and T₂ are identical and represent alkyl (C₁-C₈) or cycloalkyl (C₃-C₈);

R_d and R_and are identical and represent alkyl (C₁-C₈) or cycloalkyl (C₃-C₈);

(preferably T₁ = T₂ = R_d = R_and = methyl).

These Pt / carbene metal complexes are obtained according to a two-stage methodology illustrated by the following example:

1. Preparation of carbene:

<img file="ES2325985T3_D0003.tif" />

ch₃

2. Preparation of the platinum complex of formula:

<img file="ES2325985T3_D0004.tif" />

According to this earlier unpublished application, catalysts are used for the catalysis of the reaction of a compound with an ethylene double bond or with an acetylenic triple bond (unsaturated compound) with a compound containing at least one ^ Si-H moiety to form a C-Si link. Examples of compounds with an ethylene double bond are ethylene, propylene, 1-butylene, 1-pentene, 2-methylbutene-1, 1-hexene, 1-heptene, 1-octene, 3-ethylhexene-1, 1-decene, 4,4- dimethylnonene-1, vinylcyclohexene, styrene and 2-vinylnaphthalene.

Examples of compounds with an acetylenic triple bond are: ethynyl, 2-propynyl, 1-propynyl and 2-pentenn-4-ynyl.

Examples of compounds containing at least one ^ Si-H moiety are polymethylhydrogensiloxane, polydimethylsiloxane with terminal -SiH group, methylhydrogen dimethylsiloxane copolymers, methylhydrogenomethyloctylsiloxane copolymers, and methylhydrogencyclosiloxane polymers.

Patent US 5728839 also discloses metal / carbene complexes, prepared in two steps from imidazolium, benzimidazolium, triazolium, tetrazolium or pyrazolium salts (for example iodide). These metal complexes (rhodium) with heterocyclic carbenes are described as compounds that can be useful as catalysts for hydrogenation or hydroformylation of unsaturated organic compounds, such as olefins. In this US patent no reference is made to the crosslinking of silicones.

ES 2 325 985 T3

However, it could be interesting to have, in the domain of crosslinkable silicones -particularly elastomers-, catalysts that are active when hot and with little or no activity at room temperature. This would make it possible to formulate one-component, hot-crosslinkable silicone compositions that are stable for long-term storage at room temperature (shelf life in the container). One-component silicone compositions are those that comprise all the reactive species (POS Si-Vinyl / POS Si-H) and the catalyst in the same mixture. Classically, to increase the shelf life of the one-component silicone compositions, use is made of crosslinking inhibitors. Thus, with the Karstedt catalyst, the use of an inhibitor is imperative and allows, for example, the room temperature stability of a POS SiVinyl / POS Si-H composition to pass from 1 minute to 24 hours. But in this case it is a costly solution with limited efficiency, since the use of large amounts of inhibitor by its nature disturbs the behavior of the elastomer during its crosslinking.

In this state of the art, one of the essential objectives of the invention is to propose a silicone composition that is crosslinkable by hydrosilylation and which comprises as a catalyst one or more metal complexes based on heterocyclic carbenes, this catalyst having a weak activity at room temperature, in order to allow the realization of one-component compositions comprising the catalyst and compounds capable of reacting hot by hydrosilylation of unsaturated residues (eg POS SiH / POS Si-alkenyl), while being stable at room temperature for long periods of time (eg one day to several months).

Another essential objective of the invention is to propose a silicone composition that is crosslinkable by hydrosilylation that comprises as a catalyst one or more metal complexes based on heterocyclic carbenes, this composition not being the headquarters during the crosslinking of secondary reactions of isomerization or colorations capable of disturbing hydrosilylation. .

Another essential objective of the invention is to propose new metal complexes based on heterocyclic carbenes, usable as hydrosilylation catalysts, the latter having to remain stable in the reaction medium, in order to limit the formation:

❖ from undesirable by-products resulting from isomerization reactions of the olefinic double bond and / or from hydrogenation reactions, ❖ and / or from by-products that are the origin of also unappreciated colorations.

Another essential objective of the invention is to propose new metal complexes based on heterocyclic carbenes, usable as hydrosilylation catalysts, the latter having to produce a selective catalytic activity of a high qualitative and quantitative level in the reaction medium.

Another essential objective of the invention is to propose new metal complexes based on heterocyclic carbenes, usable as hydrosilylation catalysts, the latter having to be very active when hot and little or not at all active at room temperature, in order to be able to formulate one-component silicone compositions, hot-crosslinkable and stable for long-term storage at room temperature (shelf life in the container), and this, with little or no crosslinking inhibitor.

Another essential objective of the invention is to propose a hydrosilylation process, in particular for the hydrosilylation of ethylenically and / or acetylenically unsaturated compounds, in the presence of a catalyst comprising the new metal complexes referred to above.

These objectives, among others, are achieved by the present invention, which firstly concerns a silicone composition crosslinkable by hydrosilylation of at least one PolyOrganoSiloxane (POS) -A- carrier of one or more ethylenic and / or acetylenic unsaturations, with the help of at least one polyorganohydrogenosiloxane -B-, in the presence of a metallic catalyst -C- and optionally comprising at least one inhibitor -D- of the hydrosilylation reaction;

characterized in that the catalyst -C- comprises at least one compound selected from the products of formula (I):

<img file="ES2325985T3_D0005.tif" />

ES 2 325 985 T3 in which:

· M represents a metal selected from the metals of group 8 of the Periodic Table as published in Handbook of Chemistry and Physics, 65^to edition, 1984-1985;

L_Y represents a carbene of formula (II):

<img file="ES2325985T3_D0006.tif" />

<img file="ES2325985T3_D0007.tif" />

in which:

A and B independently represent C or N, understanding that when A represents N, then T₄represents nothing and when B represents N, then T₃ it does not represent anything;

T₃ and T₄ independently represent a hydrogen atom; an alkyl group; cycloalkyl optionally substituted with alkyl or alkoxy; aryl optionally substituted with alkyl or alkoxy; alkenyl; alkynyl; or arylalkyl in which the aryl part is optionally substituted with alkyl or alkoxy; O well

T₃ and T₄ they can form together and with A and B when they each represent a carbon atom, an aryl;

You and t₂ independently represent an alkyl group; an alkyl group optionally substituted with alkyl; an alkyl group perfluorinated or optionally substituted with a perfluoroalkyl group; cycloalkyl optionally substituted with alkyl or alkoxy; aryl optionally substituted with alkyl or alkoxy; alkenyl, alkynyl; or arylalkyl in which the aryl part is optionally substituted with alkyl or alkoxy; O well

T₁ and T₂ independently represent a monovalent radical of formula (V) below:

Vi - V2 (V) in which:

• V₁ is a divalent hydrocarbon radical, preferably an alkylene, • V₂ is a monovalent radical selected from the group of the following substituents:

♦ alkoxy, -OR ° where R ° corresponds to hydrogen, alkyl, aryl ♦ amine, preferably N (R °)₂, R ° corresponding to hydrogen, alkyl, aryl

T₁ and T₂ independently represent a monovalent radical of formula (W) below:

Wi - ω - W2 (W) in which:

• W₁ is a divalent hydrocarbon radical, preferably a linear or branched C alkylene₁C₁₀, eventually replaced, • ω represents:

-R¹C = CR¹5

ES 2 325 985 T3 corresponding to R¹ a H ​​or alkyl, or

-ChC- • W₂ is a monovalent radical selected from the group of the following substituents • R² = alkyl, H;

Si-alkyl or Si-alkoxy preferably -Si (R³)₃ with R³ = alkyl;

·· alcohol, preferably -C (R⁴)₂OH with R⁴ = H or alkyl;

·· ketone, preferably:

<img file="ES2325985T3_D0008.tif" />

with R⁵ = alkyl;

·· carboxy, preferably

<img file="ES2325985T3_D0009.tif" />

with R⁶ = alkyl;

Amide, preferably

<img file="ES2325985T3_D0010.tif" />

with R⁷ = H, alkyl;

Acyl, preferably

<img file="ES2325985T3_D0011.tif" />

with R⁸ = alkyl;

or the substituents T₁, T₂, T₃ and T₄ they can form, two by two, when they are located at two adjacent vertices in formula (II), a saturated or unsaturated hydrocarbon chain;

L_to and Lg are identical or different ligands from each other and each represent:

<img file="ES2325985T3_D0012.tif" />

ES 2 325 985 T3 such that in these formulas (III.1) and (III.2):

Z¹ , Z², Z³ , Z⁴, Z⁵ , Z • represent each independently:

to. hydrogen,

b. a halogen,

c. a cyano,

d. a saturated or unsaturated electrophilic hydrocarbon group, preferably adjacent to the double or triple bond,

and. being able to form two Zs together^1a6 vicinal an electrophilic ring advantageously different from the carbene L_Y of formula (II) and optionally including heteroatoms (preferably O, N, S);

• or the Z substituents¹ and Z² together they form, in (III.1), a monovalent alkenyl radical that includes at least one electrophilic residue preferably adjacent to the triple bond;

• or Z³ a Z⁶ they form two by two, in (III.2), a monovalent alkenyl radical that includes at least one electrophilic residue preferably adjacent to the double bond;

or together they form the ligand Lo of formula (IV):

<img file="ES2325985T3_D0013.tif" />

in which:

❖ AND₁ and Y₂ represent independently of each other CR_toR_b or SiR_cR_d;

❖ X represents O, NR_and or CR_F R_g;

❖ R¹⁰, R¹¹, R¹³ and R¹⁴, identical or different, they are selected from a hydrogen atom, an alkyl group and an aryl group optionally substituted with alkyl;

❖ R⁹, R¹², R_to, R_b, R_c and R_d are independently selected from a hydrogen atom; an alkyl group; acyl; aryl optionally substituted with alkyl; cycloalkyl optionally substituted with alkyl; and arylalkyl in which the aryl part is optionally substituted with alkyl;

❖ R_c and R_d are independently selected from alkyl; aryl optionally substituted with alkyl; cycloalkyl optionally substituted with alkyl; and arylalkyl in which the aryl part is optionally substituted with alkyl; or ❖ when Y₁ and Y₂ independently represent SiR_cR_d, two R groups_c together with two different silicon atoms they form a chain of formula:

R

I —X— (SI — X) -I n

ES 2 325 985 T3 in which n is an integer from 1 to 3; X is as defined above; R and R ', identical or different, take any one of the meanings given above for R_and, it being understood that, when n is 2 or 3, a single silicon atom of said chain may be substituted with one or two alkenyl or alkynyl groups; or when Y₁ and Y₂ independently represent SiR_cR_d, two R groups_c bonded to different silicon atoms together form a saturated hydrocarbon chain, forming the two R groups_c together with said silicon atoms and X a 6 to 10 membered ring; or ❖ when Y₁ and Y₂ independently represent CR_toR_b, two R groups_to bonded to different carbon atoms together form a saturated hydrocarbon chain, forming the two R groups_to together with the carbon atoms that carry them and X a 6 to 10 membered ring; and ❖ R_F and R_g they represent independently of each other a hydrogen atom; an alkyl group; acyl; aryl optionally substituted with alkyl; cycloalkyl optionally substituted with alkyl; arylalkyl in which the aryl part is optionally substituted with alkyl; a halogen atom; an alkenyl group; an alkynyl group; or a SiG group₁G₂G₃ where G₁, G₂ and G₃ they are independently of each other alkyl; alkoxy; aryl optionally substituted with alkyl or alkoxy; or arylalkyl in which the aryl part is optionally substituted with alkyl or alkoxy.

The presence of the specific metal / carbene-heterocyclic complexes in the compositions according to the invention gives them great stability in the ambient atmosphere under normal conditions of temperature, humidity and pressure. Such silicone compositions can be stored in a one-component form, in the non-crosslinked state, in the ambient atmosphere, for long periods (eg, 1 to several months). This result is even more advantageous and surprising given that in the case of certain heterocyclic metal / carbene catalysts, the use of crosslinking inhibitors can be dispensed with or at least a smaller amount can be used, which is very advantageous economically and Regarding the limitation of the negative repercussions on the crosslinking of the elastomer and its final qualities.

This stability goes hand in hand with the property of the compositions according to the invention of crosslinking hot (for example from 100 ° C) by hydrosilylation, in elastomers of good quality, particularly in the mechanical structural plane. Furthermore, the kinetics of the reaction are satisfactory.

On the other hand, no side reactions of isomerization and little evidence of undesirable colorations are observed after crosslinking of the compositions according to the invention.

These one-component silicone compositions, which have a long shelf life at room temperature, are all the more advantageous since their cost is not prohibitive. This advantage is even more pronounced when they do not contain an inhibitor.

The definition of the metal complexes of formula (I) that constitute the catalyst -C-, an essential compound of the composition according to the invention, is completed below.

The group 8 metals represented by M in formula (I) are, for example, palladium, platinum or nickel in oxidation state 0. In practice, M represents platinum in oxidation state 0.

By alkyl, it is meant a saturated, linear or branched hydrocarbon chain, optionally substituted (eg with one or more alkyls), preferably with 1 to 10 carbon atoms, for example 1 to 8 carbon atoms, better still 1 to 7 carbon atoms.

Examples of alkyl groups are particularly methyl, ethyl, isopropyl, n-propyl, tert-butyl, isobutyl, n-butyl, n-pentyl, isoamyl and 1,1-dimethylpropyl. The alkyl part of the alkoxy radical is as defined above.

By cycloalkyl is meant a mono- or polycyclic saturated hydrocarbon radical, preferably mono- or bicyclic, preferably containing from 3 to 10 carbon atoms, better still from 3 to 8. By monocyclic saturated hydrocarbon radical is meant a radical containing two or several cyclic nuclei joined to each other by σ bonds and / or condensed two by two.

Examples of polycyclic cycloalkyl groups are adamantane and norbornane.

Examples of monocyclic cycloalkyl groups are cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl.

By perfluoroalkyl is meant an alkyl that includes at least one perfluoroalkyl group, preferably having the formula:

- (CH2) pC_what F...

ES 2 325 985 T3 in which p represents 0, 1, 2, 3 or 4; q is an integer from 1 to 10; and C_whatF_{2q + 1} it is linear or branched. Preferred examples of this radical are:

- (CH2) 2- (CF2) 5-CF3 and (CF2) 7-CF3.

The term aryl designates an aromatic hydrocarbon group, having 6 to 18 carbon atoms, monocyclic or polycyclic, and preferably monocyclic or bicyclic. It should be understood that, within the framework of the invention, a polycyclic aromatic radical is understood to be a radical that contains two or more aromatic nuclei, condensed (ortho-condensed or ortho- and percondensed) to each other, that is, they contain, two by two, at minus two carbons in common. Said aromatic hydrocarbon group ("aryl") is optionally substituted, for example, with one or more C-alkyls.₁ C₃, one or more halogenated hydrocarbon radicals (eg CF₃), one or more alkoxy (eg CH₃O) or one or more hydrocarbon radicals comprising one or more ketone moieties (eg CH3CO-). As an example of aryl, mention may be made of the phenyl, naphthyl, anthryl and phenanthryl radicals.

The term arylalkyl designates an alkyl group as defined above, substituted with one or more aryl groups in its hydrocarbon chain, the group being aryl as defined above. Examples thereof are benzyl and triphenylmethyl.

By acyl is meant a group R ° -CO- where R ° represents an alkyl as defined above; either an Ar-CO- group where Ar represents an aryl group as defined above, or an arylalkyl in which "aryl" and "alkyl" are as defined above and in which the aryl part is substituted eventually eg with an alkyl.

By alkenyl, it is meant an unsaturated, straight or branched, hydrocarbon chain, substituted or not, containing at least one olefinic double bond, and more preferably a single double bond. Preferably, the alkenyl group contains from 2 to 8 carbon atoms, better still from 2 to 6. This hydrocarbon chain optionally comprises at least one heteroatom such as O, N, S.

Preferred examples of alkenyl groups are allyl and homoallyl groups.

By alkynyl, according to the invention is meant an unsaturated, linear or branched hydrocarbon chain, substituted or not, containing at least one acetylenic triple bond, and more preferably a single triple bond. Preferably, the alkynyl group contains 2 to 8 carbon atoms, better still 2 to 6 carbon atoms. As an example, mention may be made of the acetylenyl group, as well as the propargyl group. This hydrocarbon chain optionally comprises at least one heteroatom such as O, N, S.

The expression "does not represent anything" means that the substituents -T₃, or respectively -T₄, are non-existent. Indeed, in formula (II), the nitrogen atom is trivalent, so that when A or B represents N, the nitrogen atom cannot represent any additional substituent.

Preferably, in the carbene ligands of formula (II):

► T₃ and T₄ represent a hydrogen atom or together form a phenyl, ► and / or T₁ and T₂, identical or different, represent alkyl (C₁-C₈) or cycloalkyl (C₃-C₈), preferably from the group of radicals comprising: methyl, n-propyl, n-pentyl, neo-pentyl (CH2-C (CH3) 3), cyclopentyl, cyclohexyl, adamantyl, allyl (-CH₂-CH = CH₂), methallyl (-CH₂-C (CH₃) = CH₂), propargyl, homopropargyl (- (CH2) 2-ChCH), or - ~^C--^C&lt;^CH3 ^Í3 - (CH₂y ^ C = C— Si (CH₃)₃ or: - (CH₂)_{r = 1a4}-amine (for example N (CH₃)₂) or - (CH₂)_{r = 1a4}-alkoxy (for example O (CH₃)₂);

► and / or A and B both represent a carbon atom.

ES 2 325 985 T3

According to a variant, the carbenes of formula (II) that correspond to the ligand Ly in the catalyst -C-, can contain at least two condensed nuclei, that is, two substituents at least between T₁, T₂, T₃ and T₄ located at two adjacent vertices, together they form a saturated or unsaturated hydrocarbon chain, preferably containing 3 to 6 carbon atoms. By saturated or unsaturated hydrocarbon chain, it is meant a straight or branched hydrocarbon chain that may or may not contain one or more unsaturations of the olefinic double bond or acetylenic triple bond type.

When the carbenes (II) contain two condensed nuclei, they therefore respond to one of the following formulas, in which (alk) represents a saturated or unsaturated hydrocarbon chain:

<img file="ES2325985T3_D0014.tif" />

The La and β ligands of the catalyst -C- of formula (I), belonging to the composition according to the invention, can independently represent an alkynyl of formula (III.1) or an alkenyl of formula (III.2) substituted with Z radicals¹ a Z⁶ carriers of at least one electrophilic residue, active against the π-unsaturation of La and Le to promote the formation of a ligand with the metal M of the complex.

Advantageously, in formulas (III.1) and (III.2), the electrophilic moieties are selected from the group comprising:

<img file="ES2325985T3_D0015.tif" />

where:

R₁₇, R₁₈, R₁₉, R₂₀ is an alkyl, an alkenyl, an alkynyl or a trialkylsilyl substituted or not, and n 'comprises between 1 and 50.

As examples of radicals Z¹ a Z⁶, they can be cited:

❖ those selected from the group that includes:

-CN-COOCH₃, -COOCH₂CH₃, -conc₁₂h₂₅, ❖ and in the case where the substituents Z¹ and Z² they form two by two and with the triple bond, in (III.1), a Cy1 and / or Z ring² a Z⁶ form two by two, with or without the double bond, in (III.2), a Cy2 ring, these Cy1 and Cy2 rings are selected, independently and preferably, from the group comprising the following rings:

<img file="ES2325985T3_D0016.tif" />

ES 2 325 985 T3

When La and \ .β together form a ligand Lo of formula (IV), the latter is preferably of the type of those in which Y₁ and Y₂ represent, or both CR_toR_b, or both SiR_cR_d, in such a way that said complexes have the formula either (IV.1) or (IV.2):

<img file="ES2325985T3_D0017.tif" />

where the two R_to, the two R_b, the two R_c and the two R_d are identical to each other, and R⁹ = R¹²; R¹⁰ = R¹⁴; and R¹¹ = R¹³.

According to a variant, the two R_c in (IV.2) they form together:

(a) or a string

<img file="ES2325985T3_D0018.tif" />

in which n is an integer from 1 to 3; X is as defined above; and R and R ', identical or different, take any one of the meanings given above for R_dit being understood that when n is 2 or 3, a single silicon atom of said chain may be substituted with one or two alkenyl or alkynyl groups;

(b) or a saturated hydrocarbon chain, in such a way that the two substituents Rc, together with the two silicon atoms that carry them and X, form a ring with 6 to 10 links, preferably 6 to 8 links.

When the two R_c form the chain (a) in (IV.2), it is preferred that n is worth 1 or 2 (better yet, n is worth 1) and that R = R_d, the two Rd groups carried by the two silicon atoms being identical. In this case, Rd preferably represents alkyl, for example methyl. Better yet, in these compounds, R 'represents -CR₁₂= CR₁₃R₁₄; R₁₃ = R₁₁; R₁₀ = R₁₄; and R12 = R9.

In this case, it is preferred that X represents O in (IV.2). The ligand Ló then has the following formula:

<img file="ES2325985T3_D0019.tif" />

Among these compounds, it is preferred that the two Rds are identical, and advantageously represent alkyl (eg methyl).

Preferably, n is 1 or 2 and R = R_d, it being understood that when n is 2, a single silicon atom of the chain O- (SiRR'-O)_n- it can be substituted with one or two alkenyl or alkynyl groups. Better yet, R '= -CR₁₂= CR₁₃R₁₄^{and R}13 = ^R_n^{; R}10 = ^R14^{; and R}12 = ^R9.

ES 2 325 985 T3

When the two Rc together with the two silicon atoms and the group X form the chain (b), it is preferred that the two R groups_c be an 8-link ring. In this chaos, it is preferred that the two R_d are identical. The ligand Ló then has the following formula:

<img file="ES2325985T3_D0020.tif" />

where T represents alkyl, i is an integer between 0 and 5, T being located at one or more of the vertices 1, 2, 3, 4 and 5 of the previous formula.

Similarly, when Y₁ and Y₂ represent CR_toR_d in (IV.1), the two R groups_to Linked to different carbon atoms they can form together a saturated hydrocarbon chain (c), in such a way that the two groups Ra together with the carbons that carry them and X form a ring with 6 to 10 links. Preferably, the ring formed is an 8-membered ring, in which case the ligand Ló then has the following formula:

<img file="ES2325985T3_D0021.tif" />

where T represents alkyl; i is an integer between 0 and 5, T being located at one or more of the vertices 1, 2, 3, 4 and 5 of the previous formula.

When R_F and / or R_g represents SiG₁G₂G₃, it is preferred that R_F and / or R_g be trialkylsilyl, for example SiG₁G₂G₃ where G₁ = G₂ = G₃ = alkyl.

Subgroups of the Lo ligands of the metal complexes (catalyst -C-) that are included in the composition according to the invention, are made up of complexes for which:

-X = O; Y1 and Y2 independently represent SiRcRd; or

-X = NR_and; Y₁ and Y₂ independently represent CR_toR_b; or

-X = NR_and; Y₁ and Y₂ independently represent SiR_cR_d; or

-X = CR_FR_g; Y₁ and Y₂ independently represent CR_toR_b; or

-X = CR_FR_g; Y₁ and Y₂ independently represent SiR_cR_d.

Among these Lo ligands of formula (IV), those for which:

- when X represents O, Y₁ and Y₂ independently represent SiR_cR_d; or

- when X represents NR_and, Y₁ and Y₂ independently represent CR_toR_b; or

- when X represents CR_FR_g, Y₁ and Y₂ independently represent CR_toR_b.

ES 2 325 985 T3

In practice, X represents Oe Y₁ and Y₂ independently represent SiR_cR_d in the Lo ligand of formula (IV).

In the context of the invention, the term "independently represent" means that the designated substituents may be identical or different.

For example, R₁₀, R₁₁, R₁₃ and R₁₄ they are hydrogen atoms in the Lo ligands of formula (IV).

Preferred meanings of R₉ and R₁₂ they are particularly a hydrogen atom; an alkyl group; aryl optionally substituted with alkyl; and cycloalkyl optionally substituted with alkyl. Among these preferred meanings, it is particularly advantageous that R₉ and R₁₂, identical, represent a hydrogen atom; cycloalkyl (C₃-C₈) or (C1-C8) alkyl.

For example, the diolefinic ligand Ló of formula (IV) is symmetric, that is to say that R₁₀ = R₁₄; R₁₁ = R₁₃; R₉ = R₁₂ and the two groups Y₁, Y₂ are either strictly identical to each other, or AND₁ = CR_toR_b and Y₂ = CR_toR_b where the two R_to together they form a symmetrical chain, or AND₁ = SiR_cR_d and Y₂ = SiR_cR_d, where the two R_c together they form a symmetrical chain.

As regards the catalyst -C- of the composition according to the invention, a particularly preferred first group of metal complexes of formula (I.1) should be mentioned as follows:

<img file="ES2325985T3_D0022.tif" />

in which:

T1 and T2 are identical and are as defined above;

T3 and T4 are as defined above;

Rc and Rd are as defined above.

A second particularly preferred group of catalysts -C- of the composition according to the invention comprises the metal complexes of formula (I.2) below:

<img file="ES2325985T3_D0023.tif" />

in which:

T1 and T2 are identical and are as defined above;

T3 and T4 are as defined above;

Rc and Rd are as defined above.

ES 2 325 985 T3

A third particularly preferred group of catalysts -C- of the composition according to the invention comprises the metal complexes of formula (I.3) below:

<img file="ES2325985T3_D0024.tif" />

in which:

T1 and T2 are identical and are as defined above;

T3 and T4 are as defined above;

Rc and Rd are as defined above.

Additionally, the catalyst -C- of the composition according to the invention comprises the two polyorganosiloxane species reactive by polyaddition, namely POS -A- and POS -B-. The latter are selected from the POS constituted by siloxyl residues of the general formula:

Ρ²⁰) «S¡o ^₂(i '&gt;

and / or siloxyl moieties of the formula:

&lt;R²¹ )_Y (R22 KSiO ^ (II ') formulas in which the various symbols have the following meaning:

- the R symbols²⁰, R²², identical or different, each represents a group of non-hydrolyzable hydrocarbon nature, this radical being able to be:

* an alkyl, halogenoalkyl radical having 1 to 5 carbon atoms and including 1 to 6 chlorine and / or fluorine atoms, * cycloalkyl and halogenocycloalkyl radicals having 3 to 8 carbon atoms and including 1 to 4 chlorine and / or fluorine atoms, * aryl, alkylaryl and haloaryl radicals having 6 to 8 carbon atoms and including 1 to 4 chlorine and / or fluorine atoms, * cyanoalkyl radicals having 3 to 4 carbon atoms;

- the R symbols²¹, identical or different, each represents a hydrogen atom, a C2-C6 alkenyl group, a hydroxyl group, a hydrolyzable atom, a hydrolyzable group;

ES 2 325 985 T3

- x = an integer equal to 0, 1, 2 or 3;

- y = an integer equal to 0, 1, 2 or 3;

- z = an integer equal to 0, 1 or 2;

- the sum y + z is between 1 and 3;

with the condition that the POS -A- Si-alkenyl comprises at least one R moiety²¹ = alkenyl per molecule and POS -B- Si-H comprises at least one R residue²¹ = hydrogen per molecule;

with preference

R²⁰ = methyl; ethyl; propyl; isopropyl; butyl, isobutyl; n-pentyl, t-butyl; chloromethyl; dichloromethyl; α-chloroethyl; α ,, β-dichloroethyl; fluoromethyl; difluoromethyl; α, β-difluoroethyl; trifluoro-3,3,3-propyl; trifluoro-cyclopropyl; trifluoro-4,4,4-butyl; hexafluoro-3,3,4,4,5,5-pentyl; L'-cyanoellyl; γ-cyanopropyl; phenyl; p-chlorophenyl; m-chlorophenyl; dichloro-3,5-phenyl; trichlorophenyl; tetrachlorophenyl; o-, p- or m-tolyl; a, a, a-trifluorotolyl; xylyls such as dimethyl-2,3-phenyl, dimethyl-3,4-phenyl and even more preferably methyl, phenyl, these radicals being optionally halogenated or cyanoalkyl radicals;

R²¹ = hydrogen or vinyl.

These POS -A- and -B- are, for example, respectively a polyorganovinylsiloxane and a polyorganohydrogensiloxane. Organic substituents other than reactive vinyl groups and hydrogen are, for example, methyl or cyclohexyl. Hydrogens and vinyls are carried by siloxyl moieties M = [R₃SiO-] and / or D = [- (R)₂SiO-] and / or T = [- (R) SiO-]. These hydrogenated or vinylated moieties M, D each comprise one or more H or vinyl, preferably only one.

The number of SiH or SiVi residues per molecule is greater than or equal to one and preferably at least equal to 10 and, better still, between 10 and 100.

This may represent from 0.01% to 10% (preferably 0.1 to 2%) of vinyl by weight for POS -A- and from 0.001% to 5% (preferably 0.05 to 2%) of hydrogen. by weight for POS -B-.

Suitable polymers are polymethylhydrogensiloxanes with -Si (CH₃)₃ and the -Si-terminated polydimethylsiloxanes (CH₃)₂H, the -Si-terminated methylhydrogen dimethylsiloxane copolymers (CH₃)₂H, the methylhydrogenomethyloctylsiloxanes copolymers, and the methylhydrogen cyclosiloxanes polymers.

In general, the POS -A- and -B- usable in the reaction have an average molecular weight between 1.10²and 1.10⁶ (g / mol).

For POS -A- this includes particularly, in terms of dynamic viscosity at 25 ° C, ranges:

o POS hot vulcanizable (EVC) by polyaddition, having a viscosity at least equal to 1.10⁵mPa.s, preferably between 1.10⁶ and 1.10⁷ mPa.s, and even more, for hot-vulcanizable POS (sic) oy, by polyaddition of liquid silicone elastomers (LSR), which have a viscosity preferably between 1.10⁵ and 5.10⁵ mPa.s.

According to a preferred embodiment of the invention, the silicone compositions in question are hot vulcanized POS (EVC) by polyaddition and in which the POS -A- can in practice have a viscosity at 25 ° C of eg 2.10⁶ mPa.s and POS -B- from 10 to 5,000 mPa.s (eg 300 mPa.s).

In these examples, the viscosity is measured using a BROOKFIELd viscometer according to the indications of the AFNOR NFT 76 106 standard of May 1982.

All the viscosities referred to in the present disclosure correspond to a magnitude of dynamic viscosity at 25 ° C called "Newtonian", that is to say the dynamic viscosity that is measured, in a manner known per se, with a velocity gradient. low enough shear so that the measured viscosity is independent of the velocity gradient.

The composition according to the invention can also contain a certain number of classical ingredients, in addition to the POS -A- and -B- and the catalyst -C-, including particularly at least one crosslinking inhibitor -D-, capable of slowing the polyaddition reaction and to allow the preservation of the monocomponent composition ABCD, in a not fully cross-linked state.

ES 2 325 985 T3

Thus, the invention concerns silicone compositions comprising at least one inhibitor -D - and in which the catalyst -C- is selected from the metal complexes of formula (I.1) below:

<img file="ES2325985T3_D0025.tif" />

(Π) • of the following formula (I.2):

<img file="ES2325985T3_D0026.tif" />

where:

T1 and T2 are identical and are as defined above;

T₃ and T₄ they are as defined above;

Rc and Rd are as defined above;

Z¹ aZ⁶ are exempt from electrophilic residue (s):

• and / or of the following formula (I.3):

<img file="ES2325985T3_D0027.tif" />

σ.3) in which:

T1 and T2 are identical and are as defined above;

T3 and T4 are as defined above;

Rc and Rd are as defined above;

Z¹ a Z⁶ they are free of electrophilic residue (s).

ES 2 325 985 T3

These compositions have long shelf life (pot life).

It should be noted that for certain -C- catalysts, particularly those comprising a carbene (II) and at least one (preferably two) La and Lg ligands of formula (III.1) or (III.2), it is not necessary to use an inhibitor.

Thus, the invention also contemplates silicone compositions free of inhibitor -D- and in which the catalyst -C- is selected from the metal complexes:

• with the following formula (I.2):

<img file="ES2325985T3_D0028.tif" />

(1.2) where:

T1 and T2 are identical and are as defined above;

T3 and T4 are as defined above;

Rc and Rd are as defined above;

at least one of the substituents Z¹ a Z⁶ (preferably each substituent) comprises at least one electrophilic moiety;

• and / or of the following formula (I.3):

<img file="ES2325985T3_D0029.tif" />

(1.3) in which:

T1 and T2 are identical and are as defined above;

T3 and T4 are as defined above;

Rc and Rd are as defined above;

Z¹ a Z⁶ they are free of electrophilic residue (s).

ES 2 325 985 T3

These compositions without inhibitor, are endowed - in a totally advantageous and unexpected way - with long periods of conservation ("useful life") in the ambient atmosphere. Crosslinking only takes place hot. This advantage is fundamental from the economic point of view and from the point of view of the convenience of use and storage.

Advantageously, the -D- inhibitors (if used) are selected from:

- polyorganosiloxanes, advantageously cyclic, substituted with at least one alkenyl, tetramethylvinyltetrasiloxane being particularly preferred,

- unsaturated amides,

- alkyl, alkenyl or alkynyl maleates, diallyl maleate being particularly preferred,

- acetylenic alcohols,

- alkylated, alkenylated or alkylated acetylene dicarboxylates,

- and its associations.

As regards acetylenic alcohols (see FR-B-1 528 464 and FR-A-2 373 874), it can be indicated that they form part of the preferred thermal blockers of the hydrosilylation reaction, and that they have the formula :

RMR ') C (OH) -C CH formula in which:

R^x is a linear or branched alkyl radical, or a phenyl radical;

R^Y is H or a linear or branched alkyl radical, or a phenyl radical;

being able to form radicals R^x, R^Y and the carbon atoms located in α of the triple bond optionally a ring;

being the total number of carbon atoms contained in R^x and R^Y at least 5, preferably 9 to 20.

Said alcohols are preferably selected from those with a boiling point greater than 250 ° C. Examples can be cited:

· Ethynyl-1-cyclohexanol-1;

· Methyl-3-dodecin-1-ol-3;

· Trimethyl-3,7,11-dodecin-1-ol-3;

· Diphenyl-1,1-propyn-2-ol-1;

· Ethyl-3-ethyl-6-nonin-1-ol-3;

· Methyl-3-pentadecin-1-ol-3.

These α-acetylenic alcohols are commercial products.

Such a retarder (D) is present at a maximum rate of 3000 ppm, preferably at a rate of 100 to 2000 ppm, relative to the total weight of the organopolysiloxanes (A) and (B).

As usual families of usual functional additives, which can be used in the silicone compositions according to the invention, the following can be mentioned:

fillers, hydroxylated POS oils useful as compatibilizers, adhesion promoters,

ES 2 325 985 T3 adhesion modulators, pigments, additives for thermal stability, resistance to oils, and fire (for example metal oxides), etc.

Possibly envisaged charges are preferably mineral. They can be made up of products selected from siliceous materials (or not).

With regard to siliceous materials, they can play the role of reinforcing or semi-reinforcing filler.

The reinforcing siliceous fillers are selected from colloidal silicas, fumed and precipitated silica powders or their mixture.

These powders have an average particle size generally less than 0.1 pin and a BET specific surface greater than 50 μm.²/ g, preferably between 150 and 350 m²/ g.

Semi-reinforcing siliceous fillers such as diatomaceous earth or crushed quartz can also be used.

As regards non-siliceous mineral materials, they can act as semi-reinforcing or filler mineral fillers. Examples of these non-siliceous fillers that can be used alone or in a mixture are carbon black, titanium dioxide, aluminum oxide, hydrated alumina, expanded vermiculite, unexpanded vermiculite, calcium carbonate, zinc oxide, mica, talc, iron oxide, barium sulfate, and slaked lime.

These charges generally have a particle size between 0.001 and 300 pin and a BET surface area of ​​less than 100 m²/ g.

In a practical but not limiting way, the fillers used can be a mixture of quartz and silica.

The loads can be treated with any suitable product.

From a weight point of view, it is preferred to use a filler quantity between 20 and 50, preferably between 25 and 35% by weight relative to all the constituents of the composition.

More generally, from the quantitative point of view, the compositions according to the invention refer to the standard proportions in the technical domain considered, knowing that the contemplated application must also be taken into account.

According to another of its aspects, the present invention concerns, as new products, complexes of formula (I), particularly useful as catalysts -C- and in which the carbene of formula (II) is such that:

- T₃ and T₄ they can form together and with A and B when they each represent a carbon atom, an aryl as defined above, preferably a phenyl;

- and / or T₁ and T₂ independently represent a monovalent radical of formula (V) below:

-V1-V2 (V) in which:

• V₁ is a divalent hydrocarbon radical, preferably a linear or branched C alkylene₁-C₁₀, optionally substituted, • V2 is a monovalent radical selected from the group of the following substituents:

♦ alkoxy, -OR^V corresponding R^v to hydrogen, alkyl, aryl ♦ amine, preferably N (R^V)₂, corresponding R^v to hydrogen, alkyl, aryl

- or T₁ and T₂ independently represent a monovalent radical of formula (W) below:

W1 - ω - W2 (W)

ES 2 325 985 T3 in which:

• W₁ is a divalent hydrocarbon radical, preferably a linear or branched C alkylene₁-C₁₀eventually replaced, • ω represents:

-R^toC = CR^tocorresponding R^to to H or alkyl,

-ChC • W2 is a monovalent radical selected from the group of the following substituents ♦ R '⁹ = alkyl, H;

♦ Si-alkyl, or Si-alkenyl or Si-alkynyl, preferably -Si (alkyl)₃;

♦ alcohol, preferably -C (R^and)₂OH with R = H or alkyl;

♦ ketone, preferably:

--c — R⁵II or with R^or = alkyl, alkenyl, alkynyl;

♦ carboxy, preferably

--C - OR⁵

II or with R^or = alkyl, alkenyl, alkynyl;

♦ amide, preferably —C - N (RP)₂

Or with R '⁹= H, alkyl, alkenyl, alkynyl;

♦ acyl, preferably

--O - C - R⁵

Or with R^or = alkyl, alkenyl, alkynyl;

ES 2 325 985 T3 corresponding to T₁ and T₂ with preference independently to a radical W of the type

<img file="ES2325985T3_D0030.tif" />

or to one of the following radicals: methyl, isopropyl, tert-butyl, n-pentyl, neo-pentyl, cyclopentyl, cyclohexyl, adamantyl, allyl, methallyl, propargyl or homopropargyl,

- or the substituents T₁, T₂, T₃ and T₄ they can form two by two, when they are located at two adjacent vertices in formula (II), a saturated or unsaturated hydrocarbon chain.

Another subject of the invention is other new metal complexes of formula (I) in which:

Ly is as defined above,

La and Lj6 independently correspond to the compounds of formulas (II), (III.1) or (III.2) as defined above.

Examples of these new catalysts include:

• those with the following formula (I.2):

<img file="ES2325985T3_D0031.tif" />

(1.2) in which:

T1 and T2 are identical and are as defined above;

T3 and T4 are as defined above;

Rc and Rd are as defined above;

• or those with the following formula (I.3):

<img file="ES2325985T3_D0032.tif" />

ES 2 325 985 T3 in which:

T1 and T2 are identical and are as defined above;

T3 and T4 are as defined above;

Rc and Rd are as defined above.

It should be noted that in these formulas (I.1), (I.2), but also (I.3), platinum can be replaced by any metal M, as defined above.

The invention further encompasses any catalytic composition that comprises, as active material, one or more metal complexes (I) such as defined above, and that contains at least one La or L ^ ligand (better yet two) of formula ( III.1) or (III.2).

Such catalysts (particularly hydrosilylation) have in particular that they can be formed in situ, in silicone compositions of the type corresponding to the invention, provided that they comprise ligands La and I of formula (III.1) or ( III.2), for example as an inhibitor -D-. This or these ligands La and I of formula (III.1) or (III.2) are capable of displacing the initial ligands Lo of the catalyst -C-. In this case, they are latent catalysts. The present invention obviously encompasses this case of figure.

Another object of the invention is constituted by a process for hydrosilylation of olefins or acetylenic derivatives (for example hydrosilylation of one or more POS -A- with the help of one or more POS -B-), characterized in that it consists of using the composition of silicone as defined above and / or the catalytic composition also described above.

According to an advantageous variant in which at least one latent catalyst is used as described above, a silicone composition according to the invention is used, such as that presented above and which includes at least one inhibitor -D- which allows the in situ formation of at least one metal complex that includes at least one La or Lj6 ligand, of formula (III.1) or (III.2).

Surprisingly, when hydrosilylation is carried out using the metal complexes prepared by the process according to the invention as catalysts, the formation of these by-products is very limited. More particularly, there is a strong reduction in the rate of isomers formed, as well as a weak coloration, resulting from the decomposition of the catalyst.

The hydrosilylation reaction can be carried out in a solvent or in the absence of a solvent. In a variant, one of the reagents can play the role of solvent: for example, the compound with an ethylenic double bond or with an acetylenic triple bond.

Suitable solvents are solvents miscible with the compound containing the Si-H moiety.

Under the conditions of the hydrosilylation reaction, the catalyst complex must be solubilized in the reaction medium.

Examples of solvents that can be used for hydrosilylation are in particular aliphatic hydrocarbons (such as pentane, hexane, heptane, pentamethylheptane or the distillation fractions of petroleum); aromatic hydrocarbons (such as benzene, toluene and xylenes: ortho-xylene, para-xylene and meta-xylene); halogenated aliphatic or aromatic hydrocarbons (such as tetrachlorethylene); or ethers (such as tetrahydrofuran or dioxane).

The hydrosilylation reaction can be conducted at a temperature between 15 ° C and 300 ° C, for example between 20 and 240 ° C, better still between 70 and 200 ° C, particularly between 50 and 150 ° C, and most preferably between 100 and 100 ° C (sic).

The relative amount of unsaturated compound and compound with Si-H moiety can be controlled to ensure reaction of all unsaturations with Si-H bonds.

Generally, the molar ratio of unsaturations to Si-H bonds varies between 1: 100 and 10: 1.

According to the invention, the hydrosilylation reaction is carried out in the presence of a catalytic amount of one or more complexes according to the invention. By catalytic amount is meant less than 1 molar equivalent of platinum in relation to the amount of unsaturations present in the reaction medium.

In general, it is sufficient to introduce into the reaction medium less than 1000 ppm, preferably less than 100 ppm, better still less than 50 ppm of platinum calculated relative to the total mass of the unsaturated compound and of the compound with Si-H moieties. .

ES 2 325 985 T3

As regards the preparation of the composition according to the invention, it is a question of using and mixing compounds -A-, -B-, -C-, optionally -D- and one or more additional traditional additives.

Mixing operations are entirely within the reach of the skilled person.

The POS -A- and -B-, the -D- inhibitors and the other classical additives such as fillers, are commercial products totally available and accessible to the person skilled in the art.

In the case of the metal complexes (I) that form the -C- catalysts, it has been previously seen that the

<img file="ES2325985T3_D0033.tif" />

with La and / or Lg, of formula (III.1) or (III.2), can be obtained from complexes (I) in which ly has the formula (II) and La and Lg have the formula (IV) , the latter being displaced in situ by -D- inhibitors of formula (III.1) or (III.2).

These complexes (I) in which ly has the formula (II) and La and Lg have the formula (IV) are prepared in a conventional manner, for example from complexes known from the prior art by ligand exchange, that is by addition of the appropriate carbene of formula (II) to a metal complex of the metal M, in solution, designated the precursor complex.

Suitable precursor complexes are, for example, the Karstedt complex of the formula:

Pt2 [ViMe2Si - O - SiMe2Vi] 3 in which Vi represents the vinyl radical.

The complexes of formula (I) are generally prepared from precursor complexes containing, as ligand, at least one diolefinic compound of formula (IV.P):

<img file="ES2325985T3_D0034.tif" />

in which R₁, R₂, R₃, R₄, R₅, R₆, X, Y₁ and Y₂ they are as defined above for formula (I).

These ligands are commercially available, or are easily prepared by one of ordinary skill in the art from commercial compounds.

ES 2 325 985 T3

When X represents NR_and and Y₁ and Y₂, independently of each other, represent CR_toR_b, the compounds of formula (IV.P) contain amines that are easy to prepare by using the classical processes of organic chemistry. Thus, when Ra is other than a hydrogen atom, these amines can easily be prepared from the corresponding primary amine of formula RaNH2 by the action of appropriate chlorides preferably in the presence of an organic or mineral base.

When diolefin (IV.P) is symmetric (that is, R₄ = R₃; R₅ = R₂; R₁ = R₆; and Y₁ = Y₂), R is reacted_andNH₂ with two equivalents of a chloride of formula:

Cl-CRaRb-CR3 = CR1R2 (IV.P ') in the presence of a base.

When diolefin (IV.P) is asymmetric, it is preferable to protect the amino group of R_toNH₂ with an appropriate conventional protecting group P before reacting the resulting compound of formula R_andNHP on the chloride of formula (IV.P ”):

Cl-CRaRb-CR3 = CR1R2 (IV.P ") in the presence of an appropriate base.

Then, after deprotection, the resulting amine is reacted with a chloride of formula (IV.P "'):

Cl-CRaRb-CR4 = CR5R6 (IV.P "') in order to obtain the expected amine.

In formulas IV.P ', IV.P ", IV.P"' above, the R substituents₁, R₂, R₃, R₄, R₅ and R₆ they are as defined for formula I; Ra, Rb are as defined above.

The protecting groups P of the amine functions as well as the corresponding deprotection methods are described in Protective Groups in Organic Synthesis, Greene TW et Wuts PGM, ed. John Wiley et Sons, 1991, and in Protecting Groups, Kocienski PJ, 1994, Georg Thieme Verlag.

When R_and represents a hydrogen atom, it is desirable to select, as the starting compound, the following amine of formula IV.Q, previously protected at the amino function level with a protecting group P as defined above:

NH2 - CRa²Rb² - CR3 = CR1R2 (IV.Q).

The protected amine IV.Q is reacted with a chloride of formula VI as defined above, preferably in the presence of a base, and then by deprotection of the amino function, the expected compound of formula (IV.P ).

Suitable bases are for example an organic base selected from triethylamine, diisopropylamine, pyridine and N, N-dimethylaniline, or a mineral base such as NaOH, KOH, NaHCO3, Na2CO3, KHCO3 and K2CO3.

When X represents O and Y represents CRaRb, the compounds of formula (IV) are ethers. These ethers are commercially available or are prepared in a manner known per se from commercially available compounds.

Compounds of formula IV in which X represents CR_FR_g and Y represents CR_toR_b they are diolefins readily accessible to the person skilled in the art by synthesis or are commercially available.

Compounds of formula (IV) in which X represents NRa where Ra represents H or alkyl; R1 = R6, R2 = R₅, R₃ = R₄; and Y₁ = Y₂ = SiR_cR_d can be prepared by the action of an amine R_to-NH₂ with two equivalents of a silyl chloride of formula:

ClSiRcRd - CR3 = CR1R2 in which R_c, R_d, R₁, R₂ and R₃ they are as defined above.

ES 2 325 985 T3

Compounds of formula IV in which X represents NR_to, where R_to as defined above in formula (I); Y₁ = Y₂ = SiR_cR_d where R_d is as defined above in formula I; the two R groups_c together they form the chain:

NRa - (SiRdRc⁰ - NRa) n in which Ra and Rd are as defined above; n represents an integer from 1 to 3; Rd ° represents -CR₃= CR₁R₂; R₁ = R₆; R₂ = R₅ and R₃ = R₄, can be prepared by reacting the amine R_to-NH₂ with silyl chloride of formula:

Cl₂Sir_d - CR₃ = CR₁R₂ in which Rd, R1, R2 and R3 are as defined above.

The compounds of formula (IV) in which X represents O, and Y1 and Y2 represent SiRcRd are linear, branched or cyclic siloxanes that are commercialized or whose preparation is possible from commercial compounds, by using classical processes of the prior art. . Examples of preferred formula IV siloxanes are ViME₂SiOSiMe₂Vi and (MeViSiO)₃, the second formula representing a cyclosiloxane in which Vi represents vinyl.

As regards the symmetric compounds of formula IV, that is, those for which R₁ = R₆; R₂ = R₅; R3 = R4 and Y1 = Y2, any one of the following synthetic variants can be used.

(Variant A): For the preparation of said symmetric siloxanes of formula IV for which R₁, R₂, R₃, R_c and R_dare independently selected from alkyl, aryl, alkenyl and alkynyl, a silyl chloride of formula Cl2SiRcRd can be reacted with an organometallic compound of formula:

CR1R2 = CR3 - Mg - Hal where R₁, R₂, R₃ they are as defined above and hal represents a halogen atom under the usual reaction conditions involving magnesian derivatives.

(Variant B): For the preparation of said symmetric siloxanes of formula IV for which R1 = R2 = R3 = H and Rc, Rd are selected from alkenyl, alkynyl, aryl and alkyl, a silyl chloride of formula can be reacted Cl2SiRc-CH = CH2 with an organometallic compound of formula:

Rd - Mg - hal in which Rd is as defined above and hal represents halogen.

For the use of this variant, the person skilled in the art may refer to J. Gen. Chem., USSR, 1977,47,14021406.

(Variant C): For the preparation of said symmetric siloxanes of formula IV in which R1 = R3 = H and R2 represents alkyl, a siloxane of formula can be reacted:

H - SiRcRd - O - SiRcRdH with two equivalents of an acetylenic hydrocarbon of formula H-ChC-R₂ in which R₂ it is as defined above.

Cyclic siloxanes of formula IV are described in US 4593084.

Compounds of formula IV in which X represents CR_FR_g and Y₁ and Y₂ independently represent -SiR_cR_dcan be prepared by using a process analogous to one of those described in:

- J. of Organometallic Chemistry, 1996, vol. 521, 99-107 (process that is more particularly suitable for the preparation of the symmetric compounds of formula IV in which Y1 = Y2; Rf = Rg = H; Rc and Rd represent alkyl or aryl optionally substituted with alkyl; R3 represents a hydrogen atom; alkyl; or optionally substituted aryl; and R₁, R₂ are selected from a hydrogen atom and an alkyl):

- J. of Organometallic Chemistry, 1997, vol. 545-546,185-189 (process that is more particularly suitable for the preparation of symmetric compounds of formula IV in which Y1 = Y2; Rf = Rg = Cl or Br; Rc and Rd represent alkyl; R1 = R2 = R3 = an atom hydrogen);

ES 2 325 985 T3

- J. Chem. Soc., Perkin Trans II, 1987, p. 381 (process that is more particularly suitable for the preparation of the symmetric compounds of formula III in which Y₁ = Y₂; R_F = R_g = SiG₁G₂G₃; R_c and R_d represent alkyl; R₁= R₂ = R₃ = a hydrogen atom).

The carbenes of formulas II can be prepared by deprotonation of imidazolium salts, tetrazolium salts, triazolium salts, or pyrazolium salts depending on the case, under the action of a base.

These reactions can be outlined as follows:

<img file="ES2325985T3_D0035.tif" />

In these reaction schemes, T₁, T₂, T₃, T₄, A and B are as defined above for formula I and X represents an anion.

The nature of anion X^- it is not critical according to the invention. Anion X^- is the anion derived from an organic or mineral Bronsted acid (protic acid). Typically, the anion X^- is derived from an acid having a pKa of less than 6. Preferably, X^- it is derived from an acid with a pKa less than 4, better still less than 2. The pKa in question in this context are the pKa of acids as measured in water.

Examples of acids are carboxylic acids of formula G_or-COOH in which G_or represents alkyl, and for example (C_1-C₂₂); or aryl, and for example aryl (C₆-C₁₈) optionally substituted with one or more alkyls, preferably one or more (C₁ -C₆); sulfonic acids of formula G_or-SW₃H in which G_or it is as defined above; and phosphonic acids of the formula Go-PO3H in which Go is as defined above; other acids are HF, HCL, HBr, HI, H2SO4, H3PO4 and HQO4.

Preferred examples of carboxylic acids are acetic acid, benzoic acid, and stearic acid. As the preferred sulfonic acid, benzenesulfonic acid will be mentioned and as the preferred phosphonic acid, phenylphosphonic acid will be mentioned.

According to the invention, the anions X^- derived from the acids HF, HCl, HBr, HI, H2SO4, HBF4 and H3PO4.

Thus, anions X^- Particularly preferred according to the invention are the halide, sulfate, hydrogen sulfate, phosphate, hydrogen phosphate and dihydrogen phosphate anions. Tetrafluoroborates and hexaphenylphosphates may also be mentioned as anions.

The bases usable for the deprotonation of the salts of formula VIII are strong bases selected from the alkali metal hydrides, the alkali metal hydroxides, the alkali metal carboxylates, the alkali metal alcoholates and the alkali metal amides.

Examples of suitable bases are therefore sodium hydride, sodium methylate, potassium tert-butylate, lithium diisopropylamide and mixtures thereof.

The deprotonation reaction is preferably carried out in a solvent capable of at least partially dissolving the starting salt of formula VIII as well as the other reagents.

The nature of the solvent also depends on the strength of the base. Indeed, in the case of a strong base and particularly reactive starting salts, it may be necessary to operate at a low temperature.

Generally, the reaction temperature is between 40 ° C and -78 ° C, preferably between 30 and -50 ° C, better still between 25 and -40 ° C, for example between 20 and -30 ° C.

Solvents usable in the carbene preparation process are cyclic ethers or not, such as diethyl ether, diisopropyl ether, tetrahydrofuran, dioxane, dimethoxyethane or diethylene glycol dimethyl ether.

Other usable solvents are dimethylsulfoxide, dimethylformamide, dimethylacetamide, hexamethylphosphorylamide: [(CH₃)₂N]₃PO and hexamethylphosphoramide [(CH₃)₂N]₃P.

ES 2 325 985 T3

The carbenes of formula II in which A and B both represent a carbon atom can also be prepared by reduction of the corresponding thionas of formula IX:

<img file="ES2325985T3_D0036.tif" />

This reaction has been described by N. Kuhn in Synthesis, 1993, 561. Preferably, the reduction is carried out in a solvent of the ether or amide type, as defined above, at a temperature between 50 and 150 ° C, in the presence of potassium.

The starting salts of formula VIII can in turn be prepared by reacting the corresponding imidazoles, pyrazoles, triazoles and tetrazoles with an appropriate acid.

The nature of anion X^- in the salts of formula VIII it depends on the acid used in this stage. Usable acids are for example those listed above and from which X is derived^-.

Another method of synthesis of the salts of formula VIII in which A = B = C is described in US 5077414.

This process comprises the reaction of an a-dicarbonylated compound X of the formula:

<img file="ES2325985T3_D0037.tif" />

in which T₃ and T₄ are as defined above with HCHO and two amines of formula T₁ -NH₂ and T₂ -NH₂ in the presence of a suitable acid.

Other methods of preparing the salts of formula VIII are proposed in Chem. Eur. J. 1996, 2, no. 12, pages 1627-1636 and Angew. Chem. Int. Ed. Engl. 1997, 36, 2162-2187.

Compounds of formula IX can be prepared by condensation of an appropriate thiourea of ​​formula XI:

<img file="ES2325985T3_D0038.tif" />

with an α-hydroxyketone of formula XII:

HO

<img file="ES2325985T3_D0039.tif" />

<img file="ES2325985T3_D0040.tif" />

<img file="ES2325985T3_D0041.tif" />

XII in which T1, T2, T3 and T4 are as defined above. Appropriate operating conditions are particularly described by N. Kuhn in Synthesis, 1993, 561.

ES 2 325 985 T3

According to a particularly preferred reaction mode of the invention, the metal complex of the invention has the formula:

<img file="ES2325985T3_D0042.tif" />

in which Ly is as defined above.

A simple method of preparing this complex consists of reacting the carbene L with the Karstedt catalyst of medium formula T₂[ViMe₂Yes-O-SiMe₂Saw]₃ in which Vi represents a radical vinyl.

This reaction can be carried out in bulk or in a solvent.

Examples of suitable solvents are cyclic ethers or not, such as diethyl ether, diisopropyl ether, tetrahydrofuran, dioxane, dimethoxyethane or diethylene glycol dimethyl ether; amides such as dimethylformamide, or dimethylacetamide; and aromatic hydrocarbons (such as toluene, xylenes and more particularly toluene).

Advantageously, the reaction is conducted in an ether, and preferably in tetrahydrofuran.

The reaction temperature is usually between 10 and 50 ° C, preferably between 15 and 35 ° C, most preferably between 20 and 25 ° C.

It is desirable to operate in the presence of a slight excess of carbene relative to platinum. Thus, the molar ratio of L-carbene to platinum generally varies between 1 and 1.3, preferably between 1 and 1.1.

A simple way of proceeding is to pour, at the appropriate temperature, a solution of the carbene in a solvent, into a reactor containing a solution of the Karstedt catalyst in this same solvent.

The molarity of the carbene and catalyst solutions is not critical according to the invention.

According to a variant, this process consists essentially of putting in the presence:

• at least one salt of formula (VIII)

<img file="ES2325985T3_D0043.tif" />

in which:

- A, B, T₁, T₂, T₃, T₄ they are as defined above;

ES 2 325 985 T3

- Z₇ independently represents an anion derived from a Bronsted acid (protic acid) preferably selected from the group comprising:

- carboxylic acids of the formula Go-COOH in which Go represents an alkyl, and advantageously a C1-C22 alkyl; an aryl, advantageously a C6-C18 aryl optionally substituted with one or more C1-C6 alkyls;

- sulfonic acids of the formula Go-SO3H in which Go is as defined above;

- phosphoric acids of the formula Go-PO3H in which Go is as defined above;

- the following mineral acids: HF, HCl, HBr, HI, H2SO4, H3PO4, HClO4 and HBF4 taken alone or in combination with each other;

- and their mixtures;

• at least one precursor complex of formula (IVp) selected from the group comprising appropriate precursor complexes (IVp) which are the Karstedt complexes of formula:

Pt2 [ViMe2Si-O-SiMe2Vi] 3 in which Vi represents the vinyl radical;

• at least one solvent (V) • and at least one base (VI).

Advantageously, solvent V is selected in such a way that the solubility of the salt (VIII) and of the base (VI) in said solvent (V) is at least 1% w / w at 25 ° C, respectively.

The solvent (V) is selected from the polar aprotic solvents whose boiling temperature at 1 atm is less than 150 ° C, preferably 120 ° C, preferably from the group comprising:

• cyclic ethers or not and in particular tetrahydrofuran (THF), diethyl ether, diisopropyl ether, dioxane, dimethoxyethane or dimethyl ether of diethylene glycol;

• dimethylformamide, dimethylacetamide, hexamethylphosphorylamide: [(CH3) 2N] 3PO and hexamethylphosphoramide (CH3) 2N) 3P;

THF being particularly preferred.

The base (s) (VI) is (are) selected from the strong bases capable of deprotonizing the salt (VIII), preferably from the group comprising:

alkali metal hydrides, alkali metal hydroxides, alkali metal carboxylates, alkali metal alcoholates and alkali metal amides, and more preferably still from the group comprising:

sodium hydride, sodium methylate, potassium tert-butylate, lithium diisopropylamide and their mixtures.

The concentration of the base (VI) in the reaction medium M / I of solvent (V) is preferably:

10^-6 &lt;VI &lt;1 and even more preferably 10 ³ &lt;VI &lt;10 '

ES 2 325 985 T3

Salt (VIII) and base (VI) are used in amounts such that the ratio R_{VI / VIII} VI / VIII normality is defined as follows:

• with preference ^RVI / VIII &lt; ¹¹ &lt; ^RVI / VIII &lt; ⁵ • and more preferably still 1 &lt;R_{VI / VIII} &lt; 3.

In summary, this process essentially consists of:

a) put in solution the salt (VIII) and the compound (IVp) in the solvent (V),

b) incorporate the base (VI) several times in the solution of (VIII) and (IVp) in (V),

c) keeping the reaction medium thus constituted under stirring, preferably protected from light, until compound (I) is formed,

d) recovering the compound (I) formed, preferably by evaporation,

e) possibly purification,

f) eventually dried.

Preferably, at least one of steps a), b), c) is carried out, preferably all three, at a temperature between 5 and 50 ° C, preferably at room temperature.

Preferably, it is used:

• at least one salt (VIII) of the formula:

<img file="ES2325985T3_D0044.tif" />

in which:

- T₁, T₂ are identical and represent alkyl (C₁-C₈) or cycloalkyl (C₃-C₈);

- T₃, T₄ they are identical and represent hydrogen or together they represent a phenyl;

- Z₁ is a halogen, preferably Cl, I, or BF₄;

• at least one Karstedt complex as defined in US patent 3775452, preferably a compound of formula (IVp):

<img file="ES2325985T3_D0045.tif" />

ES 2 325 985 T3 in which:

Rd, Re are identical and represent CH3;

• a solvent (V) comprising THF, • and at least one base (VI) comprising potassium tert-butylate (t-BuOK).

The catalysts thus prepared are usable in hydrosilylation reactions. They allow a homogeneous catalysis of the reaction.

Said catalysts also give access to one-component silicone compositions, preferably of the polyaddition EVC type, which have much longer useful lives than those prepared with classic platinum-based catalysts, and this, using only little or no -D- inhibitors. .

The invention is illustrated with the aid of the following examples.

Examples

Example 1

1- Preparation of the formula carbene

<img file="ES2325985T3_D0046.tif" />

NEITHER

CgH-n (see Chem. Em. J. 1996, 2, 1627).

For this reaction, all the glassware used is oven dried at 150 ° C overnight and then cooled under argon.

THF is distilled under sodium / benzophenone immediately before use.

A 100 ml three-necked flask is charged with 2.70 g (10 mmol) of 1,3-dicyclohexylimidazolinium chloride, and then purged with a stream of argon before being suspended in 20 ml of THF . Approximately 50 ml of ammonia is then condensed at -78 ° C in the three-neck flask, leading to partial dissolution of the salt. The acetone / dry ice bath is removed and 270 mg of 95% NaH (10.7 mmol-1.07 equiv.) Are slowly added using a solids funnel. Each NaH addition is followed by a significant gaseous evolution (H2) and the salt in suspension gradually dissolves. The reaction mixture is stirred for one hour and 30 min under reflux of the solvent. The ammonia is then evaporated and a pale yellow solution is obtained as well as a solid in suspension (NaCl). This solution, whose carbene concentration is 0.5 M in THF, is used immediately for the preparation of the complexes.

ES 2 325 985 T3

2- Preparation of the platinum complex of formula (catalyst C1)

<img file="ES2325985T3_D0047.tif" />

A Karstedt solution is prepared with 10% by weight of platinum (ie 1.52 mmol platinum) according to the process described in US 3775452.

To 3 g of this solution, kept under stirring and diluted in 10 ml of tetrahydrofuran, 3.2 ml of a 0.5 M solution of the carbene of formula are added dropwise using a bromine funnel:

<img file="ES2325985T3_D0048.tif" />

in tetrahydrofuran. The addition is complete after 10 minutes. The reaction mixture is then stirred for 50 minutes at room temperature. If necessary, the small proportion of insolubles is filtered off and the reaction mixture is concentrated in vacuo.

After concentration, a slightly yellow viscous residue is obtained. Within a few hours, an abundant white solid precipitates in the residual divinyltetramethyldisiloxane. This is filtered, washed with a few milliliters of hexamethyldisiloxane, followed by pentane. This gives 570 mg (60% yield) of an analytically pure white powder.

A fraction of this powder is crystallized from a dichloromethane / absolute ethanol mixture. The resulting crystals are analyzed by X-ray diffraction. The analysis confirms the structure of the complex obtained.

Example 2

1- Preparation of the formula carbene

<img file="ES2325985T3_D0049.tif" />

ch₃

This carbene is prepared by using the procedure illustrated in Example 1, paragraph 1, except that the 2.7 g (10 mmol) of 1,3-dicyclohexylimidazolinium chloride are replaced by 2.3 g (10 mmol) of iodide. 1,3-dimethylimidazolinium.

ES 2 325 985 T3

2- Preparation of the platinum complex of formula C2

<img file="ES2325985T3_D0050.tif" />

This complex is prepared by using the procedure of Example 1, except that the carbene used as the starting product has the formula:

<img file="ES2325985T3_D0051.tif" />

<img file="ES2325985T3_D0052.tif" />

After concentration, a yellow paste is obtained. This is filtered and washed thoroughly with hot pentane. An off-white solid is isolated (35% yield), which is recrystallized from ethanol. The resulting crystals are analyzed by X-ray diffraction. The analysis confirms the structure of the complex obtained.

Example 3

Preparation of a platinum complex (III.2) of formula (catalyst C3)

<img file="ES2325985T3_D0053.tif" />

Charge 500 mg (0.815 mmol) of the complex from Example 1 to a 50 ml one-neck flask, fitted with magnetic stirring. The flask is purged with a stream of argon. The complex is then dissolved in 25 ml of anhydrous THF. 116 µl (135 mg-0.94 mmol-5 equiv.) Of dimethylacetylene dicarboxylate are then injected. The reaction mixture is refluxed with the solvent for 2 hrs. 0 min. After returning to room temperature, the THF is evaporated in vacuo, and the solid obtained is dissolved in the minimum amount of dichloromethane. The crude product is chromatographed on a silica column (eluent: cyclohexane / ethyl acetate - 80/20). After concentration in vacuo, the yellow flakes obtained are washed with propan-2-ol and then filtered under vacuum with suction. 350 mg (60% yield) of an analytically pure yellow powder are obtained.

ES 2 325 985 T3

Example 4

Preparation of one-component silicone compositions comprising the POS -A- and -B- and the catalysts

-C1-, -C2- or -C3- of Examples 1,2 and 3 respectively

In order to form a homogeneous phase with the silicone medium, the catalysts -C1-, -C2- and -C3- of Examples 1, 2 and 3 are introduced into solution in toluene. A base reaction system (M) is prepared by mixing 100 grams of a polyorganovinylsiloxane containing 0.61% vinyl by weight and 27 grams of a polyorganohydrogenosiloxane containing 0.17% by weight hydrogen. For each example, the platinum is added to the mixture (M) at a rate of 80 ppm by weight. Depending on the examples, the nature of the catalyst and that of the inhibitor vary (Tables 1 and 2 below). The Karstedt catalyst (platinum with zero oxidation degree in solution in a vinylated silicone oil) is taken as the reference system.

The inhibitors used are the following:

<img file="ES2325985T3_D0054.tif" />

Each system is evaluated by DSC and the indicated gel time corresponds to the solidification time of the reaction mixture.

The results obtained are given below in Tables 1 and 2.

TABLE 1

<td rowspan="2">Test</td><td rowspan="2">Catalytic zador</td><td rowspan="2">Inhibited dor</td><td rowspan="2">[Inh] / [Pt]</td><td rowspan="2">Temp. of Start (° C)</td><td rowspan="2">Exoter- mine ('C)</td><td colspan="2">Tgel</td>

<td>TA</td><td>60 ° C</td>

<td> 1</td><td>C2</td><td> /</td><td> /</td><td> 70</td><td> 87</td><td>1 day</td><td>(i)</td>

<td> 2</td><td>Cl</td><td> /</td><td> /</td><td> 75</td><td> 111</td><td>1 day</td><td>(or)</td>

<td> 3</td><td>C2</td><td> 11</td><td> 60</td><td> 144</td><td> 148</td><td>40 days</td><td>36 h</td>

<td> 4</td><td>C2</td><td> 12</td><td> 60</td><td> 145</td><td> 147</td><td>40 days</td><td>36 h</td>

<td> 5</td><td>Cl</td><td> 11</td><td> 60</td><td> 137</td><td> 149</td><td>40 days</td><td>36 il</td>

<td> 6</td><td>Cl</td><td> 12</td><td> 60</td><td> 141</td><td> 149</td><td>40 days</td><td>36 h</td>

<td> 7</td><td>Cl</td><td> 13</td><td> 60</td><td> 142</td><td> 149</td><td>&gt; 40 days</td><td>(or)</td>

<td> 8</td><td>C3</td><td> /</td><td> /</td><td> 115</td><td> 130</td><td>&gt; 40 days</td><td>(or)</td>

(i) molar ratio between inhibitor and platinum (ii) not determined

ES 2 325 985 T3

TABLE 2

<td rowspan="2">Against- test</td><td rowspan="2">Catalyst</td><td rowspan="2">Inhibitor</td><td rowspan="2">[Inh] / [Pt] (i)</td><td rowspan="2">Temp. of Start EC)</td><td rowspan="2">Exoter- mine</td><td colspan="2">Tgel</td>

<td>TA</td><td>60 ° C</td>

<td> 1'</td><td>Karstedt</td><td> /</td><td> /</td><td></td><td>(ii)</td><td>qq min.</td><td>(iii</td>

<td> 2'</td><td>Karstedt</td><td> 11</td><td> 60</td><td> 92</td><td> 96</td><td>5 days</td><td>5 h</td>

<td> 3'</td><td>Karstedt</td><td> 12</td><td> 60</td><td> 99,5</td><td> 103,5</td><td>5 days</td><td>5 h</td>

<td> 4'</td><td>Karstedt</td><td> 13</td><td> 60</td><td> 79</td><td> 84</td><td>1 day</td><td>(or)</td>

(i) molar ratio between inhibitor and platinum (ii) not determined (iii) not determinable due to excessively rapid crosslinking of the system

Example 5

One-component EVC silicone composition according to the invention (All parts are by weight).

5.1 Preparation

In a Z-arm kneading trough, mix for 2 hours at room temperature (23 ° C):

• 88 parts of a polyorganosiloxane that is a poly (dimethyl) (methylvinyl) siloxane blocked at each of its two ends by a trimethylsiloxy residue that contains 720 ppm of Vi groups in the chain, and that has a viscosity of 5,000,000 mPa .s at 25 ° C, • 12 parts of a polyorganosiloxane which is a poly (dimethyl) siloxane blocked at each of its two ends by a dimethylvinyloxy residue containing 120 ppm of Vi groups, and having a viscosity of 2,000,000 mPa .s at 25 ° C, • 43 parts of treated fumed silica D4 with a specific surface area of ​​60 m²/ g, • 2 parts of a polydimethylsiloxane oil blocked at its ends by dimethylhydroxysiloxy residues of viscosity 50 mPa.s at 25 ° C.

Add to this preparation, in a drum:

• 2.82 parts of a poly (dimethyl) (methylhydro) -siloxane oil blocked at each of its two ends by a dimethylhydroxysiloxy residue containing 45,000 ppm of H groups that have a viscosity of 300 mPa.s at 25 ° C, • 3.75 ppm of metallic platinum provided in the form of a platinum (0) complex.

• 225 ppm of a SiH / SiVi addition reaction inhibitor which is diallyl maleate.

5.2 Characterization of the composition

A fraction of the homogeneous mass obtained is used to measure the mechanical properties of the silicone elastomer resulting from the hot vulcanization of the polyorganosiloxane composition. To do this, the fraction of homogeneous mass retained for this purpose is then vulcanized for 10 minutes at 170 ° C, operating in a suitable mold that makes it possible to obtain 2 mm thick plates. Plates are obtained in the unannealed state (NR). A

ES 2 325 985 T3 fraction of the plates then undergoes annealing (or aging) (R) for 4 hours at 200 ° C. Normalized samples are then taken from the set of these plates and the properties are measured:

• Shore A hardness (DSA) according to DIN 53505.

• Breaking strength (R / R) in MPa according to the AFNOR NF T46002 standard.

• Elongation at break (A / R) in% according to the previous standard.

• Elastic modulus (ME) of 100% in MPa according to the previous standard.

Another fraction of the homogeneous mass obtained in the kneader is used to measure the evolution of the Williams plasticity of the unvulcanized silicone elastomer as a function of storage time and temperature.

5.3 Results

Mechanical properties

The results are given below in Table 3.

TABLE 3

<img file="ES2325985T3_D0055.tif" />

ES 2 325 985 T3

Comments:

The composition according to the invention leads to an elastomer having slightly higher mechanical properties than those obtained with a classical composition, without Pt / carbene-cyclohexyl catalyst, but with Pt Karstedt.

Williams plasticity

The results are given below in Table 4.

TABLE 4

<td>I PT Karstedt,</td><td>features</td><td>25 ° C</td><td>50 ° C</td>

<td>Counter-example</td><td>Time (days)</td><td> 38</td><td> 2</td>

<td></td><td>Increase in consistency%</td><td> 100</td><td> 100</td>

<td rowspan="2">Example 1 catalyst: Pt carbenocyclohexyl ........ ...</td><td>features</td><td>25 ° C</td><td>50 ° C</td>

<td>Time (days)</td><td> 80</td><td> 8</td>

<td></td><td>Increased consistency (% 9</td><td> 66</td><td> 100</td>

Comments:

The shelf life of the composition according to the invention in the container is clearly greater than that obtained with a classical composition without Pt / carbene-cyclohexyl catalyst, but with Pt Karstedt.