WO1995025734A1

WO1995025734A1 - Platinum complexes and light-activatable hydrosilylation catalysts containing same

Info

Publication number: WO1995025734A1
Application number: PCT/FR1995/000328
Authority: WO
Inventors: Reinhard Meuser; Gérard Mignani
Original assignee: Rhone Poulenc Chimie
Priority date: 1994-03-18
Filing date: 1995-03-17
Publication date: 1995-09-28
Also published as: AU2076295A; FR2717482B1; FI963668A0; AU680129B2; FI963668A; JPH09507677A; CA2185823A1; EP0750623A1; FR2717482A1

Abstract

Novel catalyst systems consisting of organoplatinum complexes that are photoactive in the hydrosilylation cross-linking of polyorganosiloxanes Si-H and Si-Vi or Si-epoxy. Said platinum complexes have formula (I), wherein n is 1 or 2, and L is an advantageously chromophoric ligand of one of a variety of kinds. The platinum complexes have a degree of oxidation of 0 and may be used as a basis for developing light-activatable and optionally heat-activatable, stable and high performance hydrosilylation catalyst systems. Light-cross-linkable compositions containing the polyorganosiloxanes Si-H/Si-Vi or Si-epoxy, one of the catalyst systems mentioned above and optionally various other additives such as heat blockers and/or excess ligand (L) are also disclosed. Said systems are suitable for use in a silicone composition which is light-cross-linkable by hydrosilylation and useful as a non-stick coating, e.g. for paper.

Description

PLATINUM COMPLEXES AND PHOTOACTIVABLE HYDROSILYUTION CATALYSTS CONTAINING THEM TECHNICAL FIELD:

The present invention relates to the field of catalysis of crosslinking reactions between polymer chains, e.g. silicones, comprising reactive radicals capable of forming interchain bridging, so as to obtain a crosslinked material having a certain hardness and a certain mechanical strength.

It is more particularly question, in the present description, of substrates to be crosslinked of polyorganosiloxane type A having, per molecule, at least one reactive radical Si-H, while being free of silicon atoms bonded to more than two atoms of hydrogen. These substrates A are intended to react with substrates of type B having, per molecule, at least one reactive unsaturated aliphatic group and / or at least one reactive function, eg epoxide, in the presence of a catalyst comprising at least one platinum complex, such a reaction being initiated or activated by light rays, of wavelength, chosen, preferably, in the field of ultraviolet (UV).

More precisely still, the present invention relates, first of all, to new catalytic systems formed by photoactive organoplatinic complexes in the crosslinking by hydrosilylation of polyorganosiloxanes A of Si-H type and of compounds B with aliphatic unsaturation and / or with reactive function. .

The present invention also relates to a hydrosilylation process in which the above-mentioned catalytic systems are used, as well as compositions which can be crosslinked by photoactivation and which contain, inter alia, the substrates A and B and the above-mentioned catalyst.

PRIOR ART:

Among the applications that can be envisaged in the context of the invention, there may be mentioned, for example: coatings formed from a mixture of silicone oils which can be crosslinked together and which are intended to form non-stick layers on fibrous supports, such as paper, dental impressions, adhesives, sealants, jointing materials, etc. For non-stick paper application, among others, cross-linking in situ by photoactivation, eg by UV irradiation, is particularly advantageous insofar as it allows high coating speeds. In addition, this in situ crosslinking can take place easily at room temperature. It also avoids the use of solvents, the elimination of which is costly and difficult.

Finally, the photoactivable nature of crosslinking reactions of this type is particularly advantageous, with regard to the savings in activation energy that this generates.

One of the crucial elements in this photoactivation crosslinking technique is of course the photochemical catalyst. It is thus sought to develop inactive catalytic systems up to temperatures greater than or equal to room temperature (30-40 ° C) and this, for as long as possible. It goes without saying that these catalytic systems are also required to have a very high reactivity to the light rays considered.

Conventionally, these catalysts are in the form of organometallic complexes (platinum or the like).

In this field, it is possible to mention in particular FALTYMEK, which reports in "Inorg. Chem., 20 (1981), 1357" of rhodium complexes active in the photocatalysis of hydrosilylation reactions. It appears that these rhodium complexes have relatively weak catalytic activities.

Ultimately, platinum has proven to be the most suitable metal for entering into the composition of these organometallic complexes.

Thus, to date, most industrial hydrosilylation reactions are catalyzed by the KARSTEDT solution (US-A-3,775,452) which is constituted by platinum complexes with formal and real oxidation state = 0 with tetramethyledivinylesiloxane (TMDVS), useful as a ligand. The average formula of these complexes can be stated as follows: [Pt ⁰ ₂ , (TMDVS) ₃ ].

The source of the platinum in this solution is formed by the catalyst of SPEIER or hexachloroplatinic acid.

This KARSTEDT catalyst has the drawback of not being part of the photoactivatable hydrosilylation catalysts. The activation adapted to this KARSTEDT catalyst is thermoactivation, which is, all the same, much more restrictive and expensive than a simple UV activation, of the type of that targeted by the invention. Another major defect of the catalyst of the KARSTEDT solution is that it has a relatively poor storage stability (gel time at 25 ° C less than or equal to 1 min).

In this state of the facts, one of the essential objectives of the present invention is to provide new platinum complexes and catalytic systems based on these platinum complexes, preferably of oxidation state = 0, said systems being useful , in particular in the hydrosilylation of polyorganosiloxanes of Si-H type and of compounds with aliphatic unsaturation (preferably ethylenic, eg Si-Vi) and / or with reactive functions:

- which are photoactivatable and possibly thermoactivable, - which are stable in atmosphere and at ambient temperature for long periods,

- and which are efficient, without sacrificing the imperatives of industrial feasibility and profitability.

Another objective of the invention is to provide a hydrosilylation process by photoactivation of reactive products, and in particular of silicones, in which the abovementioned catalytic systems are used, said process having to be easy to carry out, fast, and inexpensive.

Another objective of the invention is to propose compositions of silicone oils crosslinkable by photoactivation:

- which include the above catalytic systems,

- which are stable up to temperatures above room temperature, preferably greater than or equal to 30-40 ° C, and this over long periods

durations,

- and which are very reactive towards light radiation.

Such compositions, stable in storage, can be used, for example, for paper anti-adhesion, dental impressions, sealing or jointing materials, adhesives, or for any other application in which it is advantageous to use performs cross-linking in situ of silicone elastomers. BRIEF DESCRIPTION OF THE INVENTION:

These objectives, among others, are achieved by the present invention which relates to new platinum complexes of formal and real oxidation state = 0 and corresponding to the following formula:

with L = L ₁ when n = 1

with L = L ₂ when n = 2,

Δ R ¹ , R ² , R ³ , R ⁴ are different or similar to each other and represent an alkyl and / or acyl group, preferably an alkyl having from 1 to 18 carbon atoms, methyl, ethyl, propyl, pentyl groups , hexyl, allyl, acetyl, propionyl being particularly preferred and especially methyl, Δ L ₁ being a ligand of the following formula:

in which :

□ Z ₁ , Z ₂ are identical or different and:

◆ or are selected from the following list of radicals: - OH, -O-alkyl, -o-alkenyl, -NR ⁵ R ⁶ with R ⁵ , R ⁶ identical or different and chosen from the following groups: hydrogen, alkyl, alkenyl,

the alkyl and alkenyl residues considered above being linear or branched and containing from 1 to 6 carbon atoms,

◆ either form a single divalent radical of the type:

* - O -,

* - NR ⁷ - with R ⁷ = H, alkyl, alkenyl, phenyl, the said

groups themselves being optionally substituted by alkyl, alkenyl, aryloxy, arylalkyl radicals, aromatic structures of these latter two radicals which can carry chains with an amide group, such as -NH-CO-CH ₃ ,

* alkenylene preferably corresponding to: - R ⁸ C = CR ⁹ , with R ⁸ , R ⁹ identical or different and corresponding to hydrogen or an alkyl radical, halogenated alkoxyl.

◆ either are two atoms linked to each other and belonging to a preferably aromatic ring.

□ E ₁ , E ₂ are identical or different and representing: 0, NR ¹⁰ with R ¹⁰ = C ₁ -C ₆ alkyl or alkenyl, CR ¹¹ R ¹² with R ¹¹ , R ¹² identical or different and corresponding to a C alkyl ₁ -C ₆ , an alkoxyl, a halogen ..., oxygen being more particularly preferred.

□ Y ¹ , Y ² are identical or different and representing an alkyl, aryl radical preferably phenyl, alkyloxy, oryloxy, hydrogen or halogen,

Δ L ₂ being a ligand consisting of one of the following two residues (2 ₁ ), (2 ₂ ):

in which Y ³ to Y ⁶ on the one hand and E ³ , E ⁴ on the other hand are identical or different and correspond to the same definition as that given above for Y ¹ , Y ² and E ¹ , E ² respectively,

Y ³ and Y ⁴ and / or Y ⁵ and Y ⁶ can also together form a cyclic group, preferably an aromatic group comprising one or more aromatic rings having from 6 to 8 members, being in ortho or pericondensed form, and optionally substituted by monovalent radicals corresponding to the definition given above for Y ³ to Y ⁶ ;

and

in which

* E ₅ to E ₈ and Y ⁷ to Y ¹⁰ are as defined above

* Z ₃ , Z ₅ are identical or different and correspond to:

CR ¹³ with R ¹³ = H or lower alkyl C ₁ , C ₆ , N;

* Z ₄ is a residue comprising from 2 to 5 phenylene radicals linked together by:

♢ a valence link

♢ or by at least one of the following radicals

O, COO, linear or branched alkylene

CO, CONR ¹⁴ with R ¹⁴ = H or linear or branched C ₁ - C ₆ Δ alkyl excluding complexes for which L = L ₁ with Z ₁ and Z ₂ form a single oxygen atom, E ¹ = E ² = O, Y ¹ = Y ² = H and R ¹ = R ² = R ³ = R ⁴ = CH ₃ . DETAILED DESCRIPTION :

The ligand L is advantageously a chromophore. It can be varied in nature. This ligand L is also decisive with regard to the definition of two preferred species C ₁ and C _{2 in} accordance with the invention.

The first species C ₁ is that in which there is only one platinum atom of real and formal degree of oxidation 0, complexed with the siloxane residue and the ligand L ₁ , via the π double bonds.

The second species C ₂ has two platinum atoms, also of real and formal oxidation state 0 and complexed each with a siloxane residue and the ligand L ₂ : (2 ₁ ), (2 ₂ ).

These two preferred species according to the invention are not exclusive of other structures comprising more than two platinum atoms, associated with siloxane residues and with binding subunits, of the type of those presented above.

The subject of the invention is also a new photoactivatable catalytic system - possibly thermoactivable - based on platinum and useful in particular in the hydrosilylation between, on the one hand, polyorganosiloxanes A having, per molecule, at least one reactive radical Si- H and free of silicon atom linked to more than two hydrogen atoms and, on the other hand, of compounds B having at least one reactive group and / or at least one reactive polar function,

characterized in that it comprises platinum complexes of formula (I) as described above, without excluding complexes for which L = L ₁ with Z ₁ and Z ₂ form a single oxygen atom, E ¹ = E ² = O, Y ¹ = Y ² = H and R ¹ = R ² = R ³ = R ⁴ = CH ₃ .

It is to the Applicant's credit to have isolated these organoplatinic complexes (I) for having used them, in a completely new and unexpected manner, as a photoactivatable hydrosilylation catalyst. Indeed, one could, a priori, hardly expect that the general family of hydrosilylation catalysts of the platinum-vinylsiloxane type could constitute an interesting deposit for the selection of new catalysts or catalytic system comprising photoactivatable complexes (I) - possibly heat-activatable - efficient and stable when stored in an atmosphere and at room temperature.

Such catalytic systems are particularly advantageous in the context of in situ crosslinking techniques, for example of silicones, in which “ready-to-use” compositions are used and comprising both polymers intended for react between them and a photosensitive catalytic system, so that this considerably simplifies their application. These compositions are known to those skilled in the art under the name "single-component".

The photoactivatable catalytic systems according to the invention make it possible to control the crosslinking conditions and therefore the final mechanical properties targeted for the crosslinked elastomeric compositions. It is thus possible to adapt these to the intended application (e.g. non-stick, paper).

Taking into account the various molecular identities that can be envisaged for the complexes (I) according to the invention, it must be considered that the catalytic system of which it is a question in the present presentation, can consist of a mixture of complexes C ₁ , C ₂ with ligands of formulas (1) and / or (2 ₁ ) and / or (2 ₂ ).

According to a preferred arrangement of the invention, the complexes C ₁ are chosen from the following compounds, taken alone or as a mixture:

Advantageously, the C ₂ complexes are selected from the following compounds, taken alone or as a mixture

All these complexes (a) to (p) fall within the scope of the invention as photo (thermo) activatable hydrosilylation catalysts.

In addition, they constitute, to the exclusion of (a), new products which are objects of the invention.

According to an advantageous characteristic of the invention, the catalytic system contains, in the free state, at least one stabilizing agent formed by at least one ligand Ls of formula L ₁ or L ₂ as defined above.

In the same catalytic system, the ligand Ls forming the stabilizing agent can be identical or different to the ligands (L ₁ , L ₂ ) of the complexes (I): C ₁ , C ₂ .

Among the preferred Ls radical ligands, mention may be made of those of formula (1) with Y ¹ = Y ² = H and Z ₁ , Z ₂ forming a carbon-carbon double bond or an oxygen bridge, the latter case being particularly preferred.

According to the invention, it is advantageous to use the compound Ls in the catalytic system in an excess of 1 to 30, preferably 10 to 20 molar equivalents relative to the platinum present.

This Ls compound can in fact be considered as a catalyst inhibitor. It is moreover possible to use in combination or as a replacement for Ls other conventional inhibitors of hydrosilylation catalysts. These inhibitors also known under the name of thermal blockers make it possible to increase the "pot life" of the compositions considered (stabilities greater than 3-5 days) without harming the kinetics of hydrosililation.

As examples of such compounds, mention may be made of certain polyolefinic siloxanes, pyridine, organic phosphines and phosphites, unsaturated amides, alkyl maleates and acetylenic alcohols (Cf FR-B-1528464 and FR-A-2 372874).

These acetylenic alcohols, 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 ¹ and the carbon atom located at α of the triple bond which can optionally form a ring;

the total number of carbon atoms contained in R and R ¹ being at least 5, preferably from 9 to 20.

Said alcohols are preferably chosen from those having a boiling point above 250 ° C. Mention may be made, by way of examples:

. 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;

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

These α-acetylenic alcohols are commercial products.

The synthesis of the platinum complexes (I) according to the invention consists in reacting a ligand L with products of average formula [Pt ₂ ] [ViMe ₂ Si - O - Si Me ₂ Vi] ₃ . These products are preferably formed by a KARSTEDT catalyst solution.

This reaction can be carried out in bulk or in a solvent, such as toluene, ethanol or isopropanol.

This synthesis is simple and involves products which are neither toxic nor expensive. A priori, it meets all the criteria required to be considered industrially feasible, especially since it is characterized by good yields isolated which can be values as high as those greater than or equal to

50%.

According to a variant of the invention, the catalytic system can comprise a precursor of the complexes (I), eg C ₁ or C ₂ . Such a precursor is advantageously constituted by a composition of the starting materials for the synthesis of the complexes

(I), namely: KARSTEDT catalyst and excess ligand.

In this sense, the formation of the platinum complexes takes place in situ, before and / or during the use of the crosslinkable composition containing the precursor composition. This greatly simplifies the preparation.

Although the catalytic system according to the invention is sufficiently reactive and efficient to dispense with the use of photosensitizers, it is entirely possible, for the sake of optimization, to use such products.

Thus, in accordance with a variant of the invention, at least one photosensitizer is provided having a triplet energy greater than or equal to 31 Kcal / mole and selected from (poly) aromatic (optionally metallic) and heterocyclic products, preferably in the following list of products: toluene, pyridine, ferrocene, benzene, thioxanthone, anthracene, benzophenone, this selection being made so that the triplet lifetimes of the platinum complexes and of the photosensitizer (s) are preferably of the same order.

Advantageously, these photosensitizers are used at a rate of 5 × 10 ^-3 to

5, preferably about 1% by weight relative to the weight of the compounds A and B used.

For more details on these photosensitizers, reference is made to European patent application No. 0358452.

The photosensitive catalytic system according to the invention is non-reducible, so that it does not tend to react with the reactive Si-Hs of type A polyorganosiloxanes.

According to another of these aspects, the present invention relates to a hydrosilylation process between, on the one hand, polyorganosiloxanes A having, per molecule, at least one reactive radical Si-H and free of silicon atoms bound to more than two hydrogen atoms, and on the other hand, compounds B preferably chosen from polyorganosiloxanes and having, per molecule, at least one unsaturated aliphatic reactive group and / or at least one reactive function, process in which one implements at least one platinum complex as a catalyst. This process differs from its similar in that it consists essentially in reacting compounds A and B in the presence of a catalytic system of the type of that according to the invention described above, and / or by using simultaneously a synthesis of complexes (I) in which a precursor is formed, as described above, formed by a composition of the starting materials (excess ligand + KARSTEDT catalyst) and possibly using at least the constituents of the above catalytic system, the initiation of the reaction being at least partly carried out by photoactivation.

Advantageously, the compounds A are chosen from polyorganohydrogensiloxanes comprising:

* reasons for the following formula:

in which :

the symbols W are similar or different and representing a monovalent hydrocarbon group, free from any adverse action on the activity of the catalyst and preferably chosen from (cyclo) alkyl groups having from 1 to 18 carbon atoms included, and, advantageously, among the methyl, ethyl, propyl, octyl and 3,3,3-trifluoropropyl groups and also among the C ₆ -C ₁₂ aryl or aralkyl groups and, advantageously, among the xylyl and totyl and phenyl radicals,

all of these groups being optionally halogenated (e.g. fluorine) and / or hydroxylated and / or alkoxylated.

- a is 1 or 2, b is 0, 1 or 2, the sum (a + b) has a value between 1 and 3,

* and possibly other reasons of medium formula:

where W has the same meaning as above and c has a value between 0 and 3.

Organopolysiloxane A can only be formed of units of formula (1) or additionally comprise units of formula (2). Organopolysiloxane A can have a linear, branched or unbranched, cyclic or network structure. The degree of polymerization is greater than or equal to 2. More generally, it is less than 5,000.

Examples of units of formula (1) are:

H (CH ₃ ) SiO _1/2 , HCH ₃ SiO _2/2 , H (C ₆ H ₅ ) SiO _2/2 ,

When linear polymers are involved, these essentially consist of "D" W ₂ SiO _2/2 , WHSiO _2/2 , and "M" W ₃ SiO _1/2 or W ₂ HSiO _{1/2 units.} , WH ₂ SiO _1/2 ; the blocking terminal "M" units can be trialkylsiloxy, dialkylarylsiloxy groups.

By way of example of terminal "M" units, mention may be made of trimethylsiloxy, dimethylphenylsiloxy, dimethylethoxysiloxy, dimethylethyltriethoxysilylsiloxy groups, etc.

As examples of units "D", mention may be made of dimethylsiloxy, methylphenylsiloxy groups.

Said linear polyorganosiloxanes A can be oils of dynamic viscosity at 25 ° C of the order of 1 to 100,000 mPa.s at 25ºC, generally of the order of 10 to 5,000 mPa.s at 25 ° C, or gums having a molecular weight of the order of 1,000,000.

When cyclic polyorganosiloxanes are involved, these consist of "D" W ₂ SiO _2/2 , and WHSiO _{2/2 units} , which may be of the dialkylsiloxy or alkylarylsiloxy type.

Said cyclic polyorganosiloxanes have a viscosity of the order of 1 to 5000 mPa.s.

The dynamic viscosity at 25 ° C all the silicone polymers considered in this presentation can be measured using a BROOKFIELD viscometer, according to AFNOR NFT 76 102 standard of February 1972.

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

Examples of organopolysiloxanes A are:

- dimethylpolysiloxanes with hydrogenodimethylsilyl ends,

- dimethylhydrogenomethylpolysiloxane copolymers with trimethylsilyl ends, - dimethylhydrogenomethylpolysiloxane copolymers with hydrogenodimethylsilyl ends,

- hydrogenomethylpolysiloxanes with trimethylsilyl ends,

- cyclic hydrogenomethylpolysiloxanes.

As regards compounds B, they are selected from polyorganosiloxanes comprising similar or different units of formula:

in which :

Δ The symbols W 'correspond to the same definition as that given above for W,

Δ The symbols X are similar or different and represent a hydrogen atom or a reactive function, preferably epoxyfunctional, linked to silicon by a divalent radical eg C ₁ -C ₂₀ optionally comprising at least one heteroatom, the radicals X more particularly preferred being: 3-glycidoxypropyl, 4-ethanediyl (1,2-epoxycylohexyl) ...,

Δ The symbols Y are similar or different and represent a linear or branched C ₁ -C ₁₂ alkenyl residue, and having at least one ethylenic unsaturation at the chain end and / or in the chain and optionally at least one heteroatom;

Δ d, e and f are 0, 1, 2 or 3;

Δ d + e + f = 0, 1, 2 or 3;

the rate of SiO _{4/2 units} being less than 30% by moles;

As regards the Y residues, they are advantageously chosen from the following list: vinyl, propenyl, 3-butenyl, 5-hexenyl, 9 decenyl, 10-undecenyl, 5.9 -decadienyl, 6-11-dodecadienyl.

Organopolysiloxanes B can have a linear structure (branched or not) cyclic or network. Their degree of polymerization is preferably between 2 and 5000.

When it comes to linear polymers, these essentially consist of units "D" W ₂ SiO _2/2 , XSiO _2/2 , YSiO _2/2 , and "M" W ₃ SiO _1/2 , W ₂ YSiO _1/2 , W ₂ XSiO _1/2 , the terminal blocking "M" units can be trialkylsiloxy, dialkylarylsiloxy, dialkylvinylsiloxy, dialkylalkenylsiloxy groups. Examples of terminal "M" units that may be mentioned include trimethylsiloxy, dimethylphenylsiloxy, dimethylvinylsiloxy, dimethylhexenylsiloxy, dimethylethoxysiloxy, dimethylethyltriethoxysilylsiloxy groups, etc.

As examples of units "D", mention may be made of dimethylsiloxy, methylphenylsiloxy, methylvinylsiloxy, methylbutenylsiloxy, methylhexenylsiloxy, methyldecenylesiloxy, methyldecadienylsiloxy, methyl-3-hydroxypropylsiloxy, methylpropyl-3-glycidoxy-methyl-3-propoxy , 4'-epoxycyclohexyl) ethylsiloxy, methylbutoxysiloxy, methyl-β-trimethoxysilylethylsiloxy, methyl-β-triethoxysilylethylsiloxy.

Said linear polyorganosiloxanes B can be oils of dynamic viscosity at 25 ° C of the order of 1 to 100,000 mPa.s at 25 ° C, generally of the order of

10 to 5,000 mPa.s at 25 ° C, or gums with a molecular weight of the order of 1,000,000.

When cyclic polyorganosiloxanes B are concerned, these consist of "D" units W ₂ SiO _2/2 , WSiO _2/2 , WYSiO _2/2 , which may be of the dialkylsiloxy, alkylarylsiloxy, alkylvinylsiloxy, alkylYsiloxy type. , alkylXsiloxy; examples of such patterns have already been cited above.

Said cyclic polyorganosiloxanes B have a viscosity of the order of 1 to 5000 mPa.s.

Having this large variety of polyorganosiloxanes B, it is perfectly conceivable to use a mixture of different products of formula (3), as defined above.

The compounds B with aliphatic unsaturation useful in the context of the process according to the invention are, for example, those with olefinic or acetylene unsaturation well known in the technical field considered. In this regard, reference can be made to US Pat. Nos ^. 3,159,662, 3,220,272 and 3,410,886, which describe the above compounds.

According to an advantageous embodiment of the invention, the reaction mixture comprises compounds A and compounds B in an amount such that the molar ratio

Si-H / unsaturated groups and / or reactive function e.g. epoxy, either between 0.4 and 10 preferably between 1 and 4 and, more preferably still, is of the order of

1.7.

the catalyst being present in an amount from 1 to 400, preferably from 10 to 300 and, more preferably, from 20 to 200 ppm of platinum metal, expressed by weight relative to the compounds A and B present. The technical literature of the field considered gives all the other useful information, as for the reaction conditions of hydrosilylation by photoactivation (A / B mixture and UV irradiation at 25 ° C).

The crosslinking reactions of silicone oils, in particular hydrosilylation (e. G: Si-H / Si-Vi), catalyzed by photosensitive complexes of platinum, such as those according to the invention, pass through the formation of particles. colloids, useful as a support for platinum, according to a heterogeneous catalysis process.

According to a remarkable method of the invention, it is planned to introduce molecular oxygen into the reaction medium before photoactivation, which has positive repercussions on the crosslinking kinetics before or during photoactivation.

As already indicated above, photoactivation preferably takes place in the ultraviolet range.

The fact of coupling this photoactivation to a thermoactivation can constitute another factor further improving the performance of the process according to the invention. This thermoactivation is preferably carried out using infrared radiation and it advantageously takes place after the photoactivation.

A last aspect of the invention, which is mentioned in a nonlimiting manner in the present description, relates to a crosslinkable and in particular photocrosslinkable composition, characterized in that it comprises the compounds A and B, and a catalyst as defined above.

The amounts by weight of compounds A and B and of the catalyst are also given above.

As can be deduced from the above, the above composition can also comprise at least one photosensitizer having a triplet energy greater than or equal to 31 Kcal / mole and selected from (poly) aromatic (optionally metallic) and heterocyclic products, and preferably from the following list of products: toluene, pyridine, ferrocene, benzene, thioxanthone, anthracene, benzophenone, this selection being made so that the triplet lifetimes of the platinum complexes and (of ) photosensitizer (s) are, advantageously, of the same order.

These compositions in accordance with the invention are prepared either before (or even long before) or even immediately before the implementation of the hydrosilylation process. It should be noted that these compositions are particularly stable on storage and that, in accordance with the process of the invention, they offer rapid crosslinking kinetics. In addition, their uncrosslinked state, before exposure to the activation light radiation, offers great ease of handling, application or placement on different supports or other shaping molds.

Conventionally, the compositions and / or the method according to the invention can incorporate different additives, chosen according to the intended final application. It can be, for example, mineral or non-mineral fillers and / or pigments such as synthetic or natural fibers (polymers) ground calcium carbonate, talc, clay, titanium dioxide or silica smoke. This can improve e.g. the mechanical characteristics of the final materials.

Soluble dyes, oxidation inhibitors and / or any other material which does not interfere with the catalytic activity of the platinum complex and does not absorb in the wavelength range chosen for photoactivation, can also be added. to the composition or used in the context of the process according to the invention.

Once prepared by mixing all the above-mentioned compounds, the composition can be applied, for various purposes, to the surface of any solid substrate. These solid supports can be paper, cardboard, wood, plastic (e.g. polyester, nylon, polycarbonate), fibrous supports woven or not made of cotton, polyester, nylon etc, or a metal, glass or ceramic.

INDUSTRIAL APPLICATION: The applications, more particularly, targeted by the catalyst, the process and the compositions according to the invention are, in particular, those of cross-linkable silicone oils "in situ", useful for the preparation of non-stick coatings on fibrous supports of any kind and in particular on paper. In this application, the above compositions make it possible to achieve very high coating speeds, due to their very rapid crosslinking kinetics.

Other possible applications are, for example, dental impression materials, adhesives, sealants, sealants, adhesion primers.

The examples which follow, of catalytic systems, of compositions and of implementations of the process according to the invention, will allow better understanding of the latter and will provide an illustration of its many advantages and variants.

EXAMPLES

EXAMPLE 1: PREPARATION OF ORGANOMETALLIC COMPLEXES OF

PLATINUM (0) ENTERING INTO THE COMPOSITION OF THE CATALYTIC SYSTEM ACCORDING TO THE INVENTION. The operating method used consists in reacting a ligand of type π (maleic anhydride, Benzoquinone, maleimide, etc.) on the KARSTEDT complex of ideal formula: Pt ₂ (ViMe ₂ Si-O-SiMe ₂ Vi) ₃ . This reaction can be carried out in bulk or in a solvent such as toluene, ethanol or isopropanol, according to the following sequences:

1.1. OPERATING MODE:

Is introduced slowly into a toluene solution of the KARSTEDT catalyst (~ 10% by mass of Pt), the ligand in a Ligand / platinum molar ratio equal to 1 or 1/2 depending on the desired complex. After complete addition, the mixture is brought to 60 ° C. for 30 min. The mixture is allowed to cool, filtered through cellulose and the solvent is evaporated. We obtain a solid which is washed twice with petroleum ether (50 ml). The solid recovered is dried under vacuum pump at 25 ° C for 4 h.

1.2. RESULTS:

TABLE 1 below collates the results obtained. All the platinum complexes prepared were characterized by IR, NMR and microanalysis.

EXAMPLE 2 KINETICS OF HYDROSILYLATION OF SILICON A OILS

REASONS Si-H / Si- Vi.

Fig. 1 attached represents the kinetics of hydrosilylation of silicone oils with Si-H and Si-Vi units. The silicone oils used have the following structures: - Oils with Si-H units: Me ₃ SiO - (- SiMe ₂ O) _15.6 (-SiMeHO) _8] -SiMe ₃

- Si-Vi pattern oils: ViSiMe ₂ O - (- SiMe ₂ O) ₉₇ -SiMe ₂ Vi

2.1. OPERATING MODE:

The catalytic systems to be tested and an excess of ligand are introduced into the Si-Vi pattern oil. Then add this mixture to the Si-H pattern oil. The platinum level is 200 ppm relative to the total mass. The Si-H / Si-Vi molar ratio is 1.7. 20 molar equivalents of ligand are used. The irradiation is carried out using an HPK 125 lamp with a power: 120 mJ / cm ² .mn. The thickness of the film studied is 24 μm. The kinetics of disappearance of the Si-H patterns is carried out by FTIR by measuring the decrease in the vibration band v Si-H. The tests are carried out at 25 ° C. TABLE 2 below brings together the main systems used.

2.2. FREEZE TIME:

TABLE 3 below collates the gel times for some of the catalytic systems used, comprising or not ligands. This determination was carried out protected from light by mixing the catalyst (200 ppm Pt / total mass) with a mixture of silicone oils with Si-H and Si-Vi units described in Example 2 (Molar ratio Si-H / Si-Vi = 1.7). The ligand is introduced with an excess of 20 molar equivalents relative to the platinum complex. EXAMPLE 3: MIXED SYSTEM.

Fig. 2 attached represents the kinetics of hydrosilylation of a mixture of silicone oils with Si-H / Si-Vi units described in Example 2, catalyzed by the following complex:

(200 ppm Pt / total mass) in the presence of 20 molar equivalents of maleic anhydride. The operating conditions are identical to those described in Example 2.

EXAMPLE 4: COMPARATIVE TESTS

Fig. 3 attached represents the comparison of the kinetics observed for the hydrosilylation of silicone oils with Si-H / Si-Vi units (identical to those of Example 2) with the two catalytic systems:

The operating conditions are identical to those described in Example 2.

These tests show that the system studied has no induction period and is more effective than the KARSTEDT + Benzoquinone catalyst.

EXAMPLE 5: ADDITION OF BLOCKER

5.1 KINETICS:

Fig. 4 represents the various kinetics observed using the catalytic system of the following formula:

(200 ppm Pt / total mass) and various ligands and blockers.

The following three systems J, K, L are tested:

The operating conditions are identical to those described in Example 2.

5.2 FREEZING TIME: In the absence of UV irradiation, we observe the freezing time given in TABLE IV below, at 25 ° C. The comparison of the gel times of one of the catalytic systems of the invention and of a known KARSTEDT catalyst makes it possible to show the thermal stability of the catalytic systems according to the invention. The silicone oils used are identical to those described in Example 2 (Si-H / Si-Vi molar ratio = 1.7). These measurements are carried out protected from light.

EXAMPLE 6: CATALYTIC SYSTEMS WITH THERMAL BLOCKERS:

COMPARISON BETWEEN DIFFERENT PREPARATION METHODS

6.1 CATALYTIC SYSTEMS:

(O): obtained by simultaneous mixing of the KARSTEDT catalyst with 10 molar equivalents / Pt of ethynyl cyclohexanol = thermal blocker and 10 molar equivalents / Pt of benzoquinone (= ligand L).

(P): obtained by mixing the KARSTEDT catalyst with 1 molar equivalent / Pt of benzoquinone (= L) for 2 h at 25 ° C., 20 molar equivalents / Pt of ethynyl cyclohexanol then being added.

(Q): The catalyst below is mixed:

and 20 molar equivalents / Pt of ethynyl cyclohexanol.

6.2 PROCEDURE:

The catalytic mixture is introduced into an oil with Si-Vi units (idem example NO 2) and then into a silicone oil with Si-H units. The Si-H / Si-Vi molar ratio = 1.7. A film with a thickness of 24 μm is produced. The platinum concentration is 200 ppm. 6.3 DETERMINATION OF THE FREEZE TIME AT 250 ° C

6.4. KINETICS:

Figure 5 attached shows the hydrosilylation kinetics observed for O, P and Q.

EXAMPLE 7 COMPARISON OF THE NATURE OF LIGANDED BENZOQUINONE

IN PLATINUM 7.1 COMPLEXES STUDIED:

7.2 PROCEDURE:

1 molar equivalent of the R and S complexes is mixed with 20 molar equivalents / Pt of ethynyl cyclohexanol in an oil with Si-Vi units (same as example N. 2) then the oil with Si-H units is added (same as example N 2). The Si-H / Si-Vi molar ratio is 1.7. The film thickness is 24 μm.

7.3. KINETICS:

Figure 6 attached shows the hydrosilylation kinetics observed for R and S.

EXAMPLE 8 KINETICS OF HYDROSILYLATION OF SILICON OILS TO

Si-H / Si-Vi, Si-ALKYLENYLE OR Si-EPOXY PATTERNS

The silicone oils SiH and SiVi are the same as those of Example 2

The silicone oil with Si-alkenyl patterns is as follows:

8.1 PROCEDURE

200 pp

Si-H / Si-Vi (or Si-Alkenyl or Si Epoxy) molar ratio = 1.7 The conditions are the same as in Example 2.

A test is carried out for each silicone composition:

-Si-H / Si-V (T)

- Si-H / Si-alkenyl (U)

-Si-H / Si-epoxy (V)

8.2. KINETICS:

Figure 7 shows the hydrosilylation kinetics obtained.

Claims

CLAIMS:

1 - Platinum Formula Complexes:

with L = L ₁ when n = 1

with L = L ₂ when n = 2,

in which :

□ Z ₁ , Z ₂ are identical or different and:

◆ or are selected from the following list of radicals:

- OH, -O-alkyl, -o-alkenyl, -NR ⁵ R ⁶ with R ⁵ , R ⁶ identical or different and chosen from the following groups: hydrogen, alkyl, alkenyl,

the alkyl and alkenyl residues considered above being linear or branched and containing from 1 to 6 carbon atoms, ◆ either form a single divalent radical of the type:

* - O -,

* - NR ⁷ - with R ⁷ = H, alkyl, alkenyl, phenyl, the said

in which

Y ³ to Y ⁶ on the one hand and E ³ , E ⁴ on the other hand, are identical or different and correspond to the same definition as that given above for Y ¹ , Y ² and E ¹ , E ² respectively,

Y ³ and Y ⁴ and / or Y ⁵ and Y ⁶ can also together form a cyclic group, preferably an aromatic group comprising one or more aromatic rings having from 6 to 8 members, being in ortho or pericondensed form, and optionally substituted by monovalent radicals corresponding to the definition given above for Y ³ to Y ⁶ ; and

in which

* E ₅ to E ₈ and Y ⁷ to Y ¹⁰ are as defined above,

* Z ₃ , Z ₅ are identical or different and correspond to:

CR ¹³ with R ¹³ = H or lower alkyl C ₁ , C ₆ , N;

* Z ₄ is a residue comprising from 2 to 5 phenylene radicals linked together by: ♢ a valence link

♢ or by at least one of the following radicals:

O, COO, linear or branched alkylene

CO, CONR ¹⁴ with R ¹⁴ = H or linear or branched C ₁ - C ₆ alkyl

Δ excluding complexes for which L = L ₁ with Z ₁ and Z ₂ form a single oxygen atom, E ¹ = E ² = O, Y ¹ = Y ² = H and R ¹ = R ² = R ³ = R ⁴ = CH ₃ .

2 - Photo (thermo) activatable catalytic system, based on platinum, useful in particular in hydrosilylation between, on the one hand, polyorganosiloxanes A having, per molecule, at least one reactive radical Si-H and free of atom silicon linked to more than two hydrogen atoms and, on the other hand, compounds B having at least one reactive group and / or at least one reactive function,

characterized in that it comprises platinum complexes of formula (I) according to claim 1, without excluding complexes for which L = L ₁ with Z ₁ and Z ₂ form a single oxygen atom, E ¹ = E ² = O, and Y ¹ = Y ² = H and R ¹ = R ² = R ³ = R ⁴ = CH ₃ .

3 - Catalytic system according to claim 2, characterized in that it comprises complexes of formula (I) chosen from the following compounds C ₁ , taken alone as a mixture.

4 - Catalytic system according to claim 2 or claim 3, characterized in that it comprises complexes of formula (I ₂ ), chosen from the following compounds C ₂ , taken alone or as a mixture:

5 - Catalytic system according to any one of claims 2 to 4, characterized in that it comprises a mixture of complexes C ₁ and / or C ₂ .

6 - catalytic system according to any one of claims 2 to 5, characterized in that it contains, in the free state, at least one stabilizing agent formed by at least one ligand Ls of formula L ₁ or L ₂ such that defined in claim 1.

7 - Catalytic system according to claim 6, characterized in that the stabilizing agent is present in an excess of 1 to 30, preferably 10 to 20, molar equivalents relative to the Pt.

8 - Catalytic system according to any one of claims 2 to 7, characterized in that it comprises at least one thermal blocker present, preferably, chosen from acetylenic alcohols of formula:

R - (R ') C (OH) - C≡ CH

formula in which,

. R is a linear or branched alkyl radical, or a phenyl radical;

. R ¹ is H or a linear or branched alkyl radical, or a phenyl radical;

Said alcohols being more preferably selected from those having a boiling point above 250 ° C., such as:

. 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;

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

9 - Process for the synthesis of complexes according to claim 1 characterized in that it consists in reacting at least one ligand L as defined in claim 1 with products of average formula:

[Pt °] ₂ [ViMe ₂ Si-O-Si-Me ₂ -Vi] ₃ .

10 - Hydrosilylation process between, on the one hand, polyorganosiloxanes A having, per molecule, at least one reactive radical Si-H and free of silicon atom bonded to more than two hydrogen atoms, and other on the other hand, compounds B having, per molecule, at least one unsaturated aliphatic reactive group and / or at least one reactive polar function, in which at least one platinum complex is used as catalyst,

characterized in that it is based at least in part on photoactivation and in that it consists essentially in reacting the compounds A and B in the presence of the catalytic system according to any one of claims 1 to 8 and / or by putting implementing the synthesis process according to claim 9, optionally using at least one of the constituents of said catalytic system.

11 - Process according to claim 10, characterized in that the compounds A are chosen from polyorganohydrogensiloxanes comprising:

* reasons of the following formula: in which:

- the symbols W are similar or different and represent monovalent hydrocarbon groups, free from any adverse action on the activity of the catalyst and preferably chosen from (cyclo) alkyl groups having from 1 to 18 carbon atoms included and, advantageously, from methyl, ethyl, propyl, octyl and 3,3,3-trifluoropropyl groups as well as from groups aryls or C ₆ -C ₁₂ aralkyls and, advantageously, from the xylyl and totyl and phenyl radicals,

- a is 1 or 2, b is 0, 1 or 2, the sum (a + b) has a value between 1 and 3,

* and, possibly, other reasons of medium formula:

in which W has the same meaning as above and ca a value between 0 and 3.

12 - Process according to claim 10, characterized in that the compounds B, are selected from polyorganosiloxanes comprising similar or different units of formula: in which:

Δ The symbols W ′ are similar or different and represent monovalent hydrocarbon groups, free from any unfavorable action on the activity of the catalyst and preferably chosen from (cyclo) alkyl groups having from 1 to 18 carbon atoms included and , advantageously, among the methyl, ethyl, propyl, octyl and 3,3,3-trifluoropropyl groups as well as among the C ₆ -C ₁₂ aryl or aralkyl groups and, advantageously, among the xylyl and totyl and phenyl radicals,

all of these groups being optionally halogenated (e.g. fluorine) and / or hydroxylated and / or alkoxylated,

Δ The symbols X are similar or different and represent a hydrogen atom or a reactive, preferably epoxyfunctional, function linked to silicon by a divalent radical eg in C ₁ -C ₂₀ optionally comprising at least one heteroatom, the more particularly preferred X radicals being:

3-glycidoxypropyl, 4-ethanediyl, (1,2-epoxycylohexyl) ...

Δ The symbols Y are similar or different and represent a linear or branched C ₁ -C ₁₂ alkenyl residue, alkenyl residue having at least one ethylenic unsaturation at the chain end and / or in the chain and optionally at least one heteroatom;

Δ d, e and f are 0, 1, 2 or 3;

Δ d + e + f = 0, 1, 2 or 3;

the rate of SiO _{4/2 units} being less than 30% by mole.

13 - Process according to claim 12, characterized in that the residues Y are chosen from the following list: vinyl, propenyl, 3-butenyl, 5-hexenyl, 9 decenyl, 10-undecenyl, 5.9 -decadienyl, 6-11 -dodecadienyl.

14 - Process according to claim 12 or 13, characterized in that the compounds B consist of a mixture of the products of formula (3).

15 - Process according to any one of claims 10 to 14, characterized in that the reaction mixture comprises compounds A, and compounds B in an amount such that the molar ratio SiH / unsaturated group and / or reactive function is between 0 , 4 and 10, preferably between 1 and 4 and, more preferably still, that is to say on the order of 2.5 ± 0.5, the catalyst being present in an amount of 1 to 400, preferably from 10 to 300 and, more preferably, from 20 to 200 ppm of platinum metal, expressed by weight relative to the compounds A and B present.

16 - Process according to any one of claims 10 to 15, characterized in that oxygen is introduced into the reaction medium before photoactivation.

17 - Method according to any one of claims 10 to 16, characterized in that the photoactivation takes place in the field of ultraviolet.

18 - Method according to any one of claims 10 to 17 characterized in that the photoactivation is coupled to a thermoactivation, advantageously using infrared radiation and preferably occurring after said photoactivation.

19 - Crosslinkable composition characterized in that it comprises:

- compounds A according to claims 10 or 11,

- compounds B according to any one of claims 10 and 12 to 14, - and a catalytic system according to any one of claims 2 to 8. 20 - Crosslinkable composition characterized in that it comprises:

- compounds A according to claims 10 or 11,

- compounds B according to any one of claims 10 and 12 to 14, - and a composition-precursor of the catalytic system according to one

any of claims 2 to 8.

21 - Composition according to claim 20, characterized in that it comprises compounds A and B in an amount such that the molar ratio SiH / unsaturated group and / or reactive function is between 0.4 and 10, preferably between 1 and 4 and, more preferably still, of the order of 2.5 ± 0.5, the catalyst being present in an amount of 1 to 400, preferably from 10 to 300 and more preferably from 20 to 200 ppm of platinum metal, expressed by weight relative to the compounds A and B present.