FR2847900A1 - A catalytic system containing a platinum hydrosilylation catalyst and organophosphorus catalyst inhibitor used for the crosslinking of heat vulcanizable monocomponent silicone compositions - Google Patents

Abstract

A catalytic system contains a metallic hydrosilylation catalyst and organophosphorus catalyst inhibitor. The monocomponent silicone composition comprises a polyorganosiloxane bearing ethylenic or acetylenic unsaturations and a polyorganohydrogenosiloxane. The inhibitor compound is either of Formula (I) or of Formula (VIII). R, R1 - R4 = 2-30C or preferably 2-12C linear alkyl, an alkyl radical comprising one or two 4-14C or preferably 5-8C cycles, an aryl or alkylaryl radical comprising one or two aromatic 4-14C or preferably 6-8C cycles optionally substituted with one or two 1-12C or preferably 4-12C alkyls. P(OR)3 (VIII) R = 7-31C alkylaryl, preferably substituted phenyl. Independent claims are also included for: (1) a method of preparing an additive or catalytic system comprising a metallic hydrosilylation catalyst and an organophosphorus compound inhibiting the action of the catalyst at ambient temperature; and (2) a method of preparing a monocomponent, hydrosilylation crosslinkable silicone composition comprising the system.

Description

R10 / OR3

P OR _P

  R20 / \ OR4 The invention relates to new inhibitors of catalysts for hydrosilylation reactions involving polyorganosiloxanes (POS) carrying Si-H units and POSs carrying ethylenic and / or acetylenic unsaturation (s) (s), hereinafter referred to as POS carriers of Si- [ethylenic or acetylenic unsaturation] units and to the catalytic units obtained from the mixture of these inhibitors and catalysts. The invention also relates to monocomponent silicone compositions crosslinking by hydrosilylation reactions and comprising such an inhibitor or catalytic unit.

  The invention also relates to specific methods for using inhibitors of hydrosilylation catalysts, to methods for preparing mixtures of inhibitors and catalysts, to methods for preparing monocomponent silicone compositions and to compositions capable of to be obtained by the implementation of these methods.

  Conventionally, the hydrosilylation reactions allowing the silicones to crosslink are catalyzed by platinum catalysts (US-A-2,823,218, US-A-2,970,150). In practice, to date, most industrial hydrosilylation reactions are catalyzed by the Karstedt solution which consists of platinum complexes with oxidation state 0. The ideal general formula for the Karstedt complex is Pt2 (tetramethyldivinylsiloxane) 3: Me SMe \ Me Me Me Me Me \ / f 1 Ptt. St oMe Me \ ,,, Me si si / M Me? \ / / Me o Me represents methyl.

  The Karstedt complex is prepared by bringing 1, 3divinyltetramethyldisiloxane into contact with chloroplatinic acid (H2PtCI6), in the presence of NaHCO3 and an aqueous-alcoholic solvent (isopropanol). This usual catalyst and its production are described in US Pat. No. 3,775,452.

  The very strong 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 crosslinking of the elastomer begins as soon as all of the components are brought into contact. .

  More stable Pt / carbene metal complexes have been proposed.

  Thus, FR-A-2 801 887 discloses metal complexes useful as hydrosilylation catalysts, of formula: Rd Ti R3 0 APt: C- ,:

X

  Rd ReR in which R3 represents a hydrogen atom; a (C1-C8) alkyl group; or a (C3-C8) cycloalkyl group optionally substituted by (ClC4) alkyl; T1 and T2 are identical and represent (C1-C8) alkyl or (C3C8) cycloalkyl Rd and Re are identical and represent (C1-C8) alkyl or (C3-C8) cycloalkyl; (preferably T1 = T2 = Rd = Re = methyl).

  Conventionally, to increase the storage stability at room temperature (pot life) of the one-component silicone compositions crosslinkable by hydrosilylation reaction, use is made of crosslinking inhibitors which act by masking the activity of the catalyst at the ambient temperature. The activity of the catalyst is restored when the temperature is increased. Organophosphorus compounds have been proposed.

  Thus US-A-3 188 300 describes the use of various phosphine or phosphite ligands of formula: / R p R2 \ R3 in which R, R2 and R3, identical or different, are alkyl, aryl, aralkyl, alkaryl radicals , alkoxy, aryloxy, aralkoxy, alkaryloxy.

  US-A-5 380 812 provides di- and trihydrocarbylphosphines, di- and trihydrocarbylphosphine oxides, di- and triorganophosphites of formula (R '-) to H (3 -a) P and phospholene oxides. In the above formula, R1 is a substituted or unsubstituted monovalent hydrocarbon radical, for example alkyl, aralkyl, alkaryl, and a is 2 or 3.

  Mention may also be made of US-A-4,593,084, US-A-5,654,455 and US-A-6,300,455.

  The latter describes phosphite ligands of formula P (OR) 3 in which R is a C7-C31 radical or an alkylaryl radical. The preferred ligands are of formula - R1 2 P - O R3 R5 R4 - 3 The phosphines make it possible to instantly inhibit platinum but their affinity for platinum is such that the catalyst system finally obtained exhibits poor reactivity. The phosphites exhibit a more interesting inhibition / reactivity compromise.

  Beyond the choice of an inhibitor / catalyst couple, the properties of the catalytic systems can depend on the conditions of their use and on the dispersion of the inhibitor / catalyst couple in the silicone material.

  In US 6,300,455 the organophosphorus inhibitor (compound d) is added to the vinylated silicone oil (compound a) before addition of the hydrosilylation catalyst (compound c), then the polyhydrogenosiloxane (compound b) is added in turn.

  However, the organophosphorus compounds are generally little or not soluble in silicone oils, which is likely to cause poor dispersion of these compounds. As a result, the complexation of platinum, and therefore its inhibition, can be long to obtain with such a process, which therefore exposes to premature crosslinking of the final composition.

  It would be interesting to have new inhibitors which make it possible to reconcile a high inhibitory power and a good catalytic activity, and which make it possible to prepare monocomponent compositions having a satisfactory pot life ("pot-life"), eg from 1 day to several month. It would also be advantageous to have effective methods of implementing these inhibitors / catalysts.

  The present invention therefore aims to meet this need by proposing new inhibitors and more particularly a new catalytic assembly comprising a catalyst and an inhibitor, having a low activity at room temperature.

  Another objective of the invention is to propose methods of implementing inhibitor / catalyst pairs which make it possible to ensure, under the best conditions, the catalyst / inhibitor coupling and / or the dispersion of the catalyst, the inhibitor and the assemblies catalysts in a silicone composition. Yet another objective of the invention is to provide catalytic assemblies having improved ease of use, in particular for mixing them with silicone compositions.

  Yet another objective of the invention is to provide a silicone composition crosslinkable by hydrosilylation and comprising, as catalyst, such a catalytic assembly having a low activity at room temperature, so as to allow the production of single-component compositions comprising the catalyst and compounds capable of reacting hot by hydrosilylation of unsaturated units (eg POS SiH / POS Si-alkenyl), while being stable at room temperature for long periods (eg 1 d to several months).

  The subject of the present invention is therefore a catalytic assembly obtained by mixing a metal catalyst capable of catalyzing a hydrosilylation reaction and an inhibitor corresponding to the following formula (1): R1O OR3

P-R P

  R20 / \ OR4 in which: i 2 3 4 R, R, R ', R and R, identical or different, represent a linear, branched or cyclic alkyl radical, or an aryl radical substituted or not, in particular: - an alkyl radical linear or branched, having in particular from 2 to 30 carbon atoms (C), preferably from 2 to 12 C, - an alkyl radical comprising one or more rings, in particular 1 or 2, a ring which may in particular have from 4 to 14 C , preferably from 5 to 8 C, or - an aryl or alkylaryl radical, comprising one or more aromatic cycles joined or not joined, in particular 1 or 2 cycles, a cycle possibly comprising from 4 to 14 C, preferably from 6 to 8 C, optionally substituted by 1 or more, in particular from 1 to 2, 10 linear or branched alkyl (s), in particular having from 1 to 12 C, preferably from 4 to 12 C. R is advantageously a cyclic alkyl radical, and even better an alryl radical, in particular bi-phenyl.

  i 2 3 4 R1, R, R3 and R are advantageously cyclic alkyl radicals, and better still aryl radicals and more preferably alkylaryl radicals, in particular substituted phenyl, e.g. tert-butyl-phenyl. R1, R2, R3 and R4 are preferably identical.

  Compounds with aryl or cyclic alkyl radicals are preferred for their longer inhibitory activity than compounds with linear or branched alkyl radicals.

  The preferred compounds correspond to the formula (II): R5 R5 R R5 R5l - R R5 0 R5 in which the radicals R5, identical or different, preferably identical, are linear or branched alkyls, having in particular from 1 to 12 C, Preferably from 4 to 12 C. The preferred compound corresponds to formula (111): tB tBt-Bu tL / t-Bu Ox / P - / P \ oo t-Bu "tB t- Bu tBu CAS n: 38613-77-3 The metal molar ratios of the catalyst to the inhibitor can be between 1 / 0.5 and 1/10, preferably between 1/1 and 1/5.

  The catalysts targeted by the invention include all the catalysts useful for the hydrosilylation of POS carrying Si-H units and of POS carrying Si- [ethylenic or acetylenic unsaturation] units. They can therefore be platinum, rhodium, iridium, nickel, ruthenium and / or palladium compounds. They are more particularly compounds of iridium or better still of platinum.

  The platinum compound can be any complex of platinum and an organic product, eg those described in patents US-A-3,159,601, US-A-3,159,602, US-A-3,220,972 and European patents EP-A-0 057 459, EP-A-0 188 978 and EP-A-0 190 530, or any complex of platinum and vinylated organosiloxanes, eg those described in patents US-A-3,419,593, US-A-3,715,334, US-A-3,377,432 and US-A-3,814,730.

  Mention may be made of chloroplatinic acid, a chloroplatinic acid modified with an alcohol, or else a complex of chloroplatinic acid with an olefin, an aldehyde or a vinylsiloxane, among others. Patent US-A-2,823,218 discloses a hydrosilylation catalyst of the chloroplatinic acid type and patent US-A-3,419,593 relates to catalysts formed by chloroplatinic acid and organosilicone complexes of the vinylsiloxane type. . Platinum and hydrocarbon complexes useful as a hydrosilylation catalyst are disclosed by US-A-3 159 601 and 3 159 602. US-A-3 723 25 497 describes a platinum acetylacetonate and the US patent -A-3 220 972 relates to catalysts based on platinum alcoholate.

  The invention relates more particularly to the platinum / unsaturated siloxane complexes, in particular the platinum / vinylsiloxane complexes, in particular those obtained by reaction between a platinum halide and an unsaturated organosilicon material such as an unsaturated silane or an unsaturated siloxane, eg according to the invention. teaching of US-A5 3,775,452 to which a person skilled in the art can refer. The invention preferably applies to the Karstedt solution or complex described above.

  The catalytic assembly according to the invention comprises a mixture of the catalyst and the inhibitor leading to a new complex species between these two compounds. Without wishing to be bound to theory, it is believed that starting from the Karstedt complex and an inhibitor of formula (1), the new species (I ') has a structure of the type: \ Si //' R10 OR3 i O Pt <PRP - Pt O / SI R2 0 OR'R If i 2 4 R, R, R R3 and R4 having the meanings given with regard to formula (1).

  With the inhibitors of formula (II) and (111), without wishing to be bound to theory, it is believed that the new species (II ') and (111') have the following structures respectively R5 R5 R5 RP O Pt P P -> Pt O if 0 0 if t-Bu t-Bu t-Bu t-Bu O -___ O Si O Pt ---- PP --- Pt O Si --- 0 s C / PvO O t-Bu \ t-Bu t-Bu t-Bu In the formulas (1 '), (Il') and (111 '), the arrows represent the interactions between the orbitals of the atoms of P and Pt.

  The subject of the present invention is also - these new species, the use of a compound of formula (1), in particular (II) and preferably (111), as an inhibitor of a metal catalyst, in particular platinum, in particular catalyst hydrosilylation, in particular in a monocomponent silicone composition crosslinking by hydrosilylation reaction, and the use of the catalyst and inhibitor mixtures according to the invention and of these new species as catalyst in compositions catalyzed in particular by platinum, in particular silicone compositions crosslinking by hydrosilylation reactions, and more particularly still the monocomponent compositions according to the invention.

  As explained elsewhere, the catalyst is inhibited by the inhibitor at room temperature. Its activation can be induced by temperature rise.

  Very advantageously, the inhibitors according to the invention, eg the inhibitors of formula (II) and (111) are soluble in vinyl silanes such as vinyltrimethoxysilane (VTMO) and in unsaturated siloxanes, eg vinylsiloxanes and in platinum solutions / unsaturated siloxane, eg platinum / vinylsiloxane. This results in greater ease of implementation when mixing with silicone oils. For the preparation of such a catalytic solution, the catalyst solution and the inhibitor can be mixed until the inhibitor is completely dissolved. Preferably, the inhibitor is added to the catalyst solution.

  In order to give monocomponent silicone compositions the best possible properties in terms of inhibition of the hydrosilylation reaction and of controlled pot life, the Applicant has developed a particular production process. An additive or catalytic assembly, in which catalyst and inhibitor are present in the form of a complex, is first prepared. The catalyst is thus found inhibited at room temperature. This additive is intended to be added to the single-component silicone composition 10 under conditions ensuring a fine and homogeneous dispersion.

  The present invention therefore also relates to a process for the preparation of an additive or catalytic unit comprising an inhibitor / catalyst pair.

  This process applies to inhibitors of formula (1), as well as to other effective organophosphorus compounds, and in particular to inhibitors of general formula (VIII) P (OR) 3, in which R is a radical alkylaryl having in particular from 7 to 31 carbon atoms, preferably substituted phenyl radicals, eg substituted by linear or branched alkyls, preferably identical, having in particular from 1 to 12 C, preferably from 4 to 12 C, by

example t-Bu.

  Among the compounds of formula (VIII), those corresponding to the following formula (IX) are preferred R1 2 P - R R5 R 4 in which R, R 2, R ', R', R ', identical or different, represent H, an aliphatic radical, linear or branched, saturated with formula CH2n + 1 or unsaturated with formula CmH2m-1, or a radical with formula CF2, + 1, with n = 1 to 15, and m = 3 to 15, l 'all of these radicals can not all represent H. Preferably, R 2, R4 and R5 represent H and R' and R3 represent aliphatic radicals preferably identical, eg t-Bu.

  For the quantities to be used, it is possible to reason in the metal ratio of the catalyst to the inhibitor. For type (I) inhibitors, this ratio can be between 1 / 0.5 and 1/10, preferably between 1/1 and 1/5. For type (VIII) inhibitors, this ratio can be between 1/1 and 1/10, preferably between 1/2 and 1/5.

  In a first embodiment of the process of the invention (hereinafter mode 1), a solution comprising the catalyst and the inhibitor is prepared, by mixing the organophosphorus inhibitor in the catalyst. solution in an unsaturated silane or siloxane, preferably an unsaturated siloxane such as vinylsiloxane, eg in the platinum / unsaturated siloxane solution, in particular in the platinum / vinylsiloxane solution, preferably in the Karstedt solution. USA-3,775,452, to which a person skilled in the art can refer, describes unsaturated silanes and unsaturated siloxanes under the formulas (1), respectively (2) to (5). As seen above, the inhibitors of formula (I), in particular the inhibitors of formula (II) and (111), are soluble in silanes and unsaturated siloxanes, which allows easy and rapid dissolution of these inhibitors in a catalytic solution, in particular of the siloxane type, eg in the Karstedt solution, and rapid and effective inhibition of the catalyst.

  In the case of the inhibitors of formula (VIII), for example (IX), these being not soluble, the inhibitor is only dispersed in the catalytic solution.

  Catalyst inhibition takes a little longer to achieve, but is just as effective. In general, the inhibitor catalyst solution can comprise from 0.1 to 15%, preferably from 5 to 10%, by weight of platinum metal. The mixing can be carried out by any conventional stirring means, e.g. with a paddle stirrer. Complexation, that is to say the in situ formation of the inhibitor / catalyst complex, is very rapid, in particular of the order of a few minutes.

  In a second embodiment (hereinafter mode 2), the method 30 comprises - dispersing the organophosphorus inhibitor in a silicone oil or gum, it - heating the silicone oil or gum to a higher temperature at the melting or softening temperature of the inhibitor, - adding and mixing the catalyst.

  The silicone oil or gum is heated to the appropriate temperature before, during and / or after the addition of the organophosphorus derivative. According to a preferred method, the organophosphorus compound is first dispersed in the oil or gum maintained at a temperature below the melting point, and only then the composition is heated to a temperature above the melting or softening temperature of the organophosphorus compound.

  The organophosphorus compound disperses quickly, efficiently and homogeneously in the silicone oil or gum. It can generally be considered that a dispersion time greater than a few minutes, in particular of the order of 5 min to 1 h, preferably from 15 min to 30 min, is sufficient.

  The silicone material is preferably brought to a temperature higher than 11 to 50 ° C., in particular from 5 to 200 ° C., preferably from 10 to 20 ° C., above the melting or softening temperature of the organophosphorus compound used. At the selected temperature, stirring of the mixture of silicone material and inhibitor is maintained, for a sufficient time to ensure good fusion of the dispersed organophosphorus compound. It can generally be considered that a heating and stirring time greater than a few minutes, in particular of the order of 5 min to 1 h, preferably from 15 min to 30 min, is sufficient. The catalyst can then be added to the composition previously obtained. To avoid denaturing the catalyst, when necessary, the above composition is cooled to a temperature below the denaturation point of the catalyst. In general, it is preferable to bring the previous composition to room temperature, eg of the order of 25 C. According to a preferred arrangement of this method of preparation, after the previous composition has cooled, in particular to room temperature, the solution or Karstedt complex is added and the whole is mixed.

  The mixing is continued until homogeneous dispersion of the catalyst in the silicone material and the formation of an inhibitor / catalyst complex generated in situ is obtained, remarkably dispersed in a fine and homogeneous manner in the silicone gum or oil.

  The silicone gum or oil used to form this solution is chosen to be compatible with the final silicone composition. According to a preferred method, an oil or gum with a viscosity close to or identical to that of the final silicone composition or of the portion of the latter in which the inhibitor-catalyst solution will first be mixed is used. It is possible in particular to use an oil or gum, or a mixture of oils or gums, identical to one or more compounds of the final silicone composition.

  The mixing of the ingredients at the different stages is carried out using a mixing device adapted to the viscosity of the oil or gum used. For rather high viscosities, as in the case of the oils or gums used in EVCs, it is possible to use a roller mixer or an arm mixer. Preferably, an oil or a vinylised gum is used, such as POS A according to the invention, and more preferably still POS A used in the targeted single-component silicone composition.

  In both modes 1 and 2, it may be useful to add to the composition 20 each time obtained, one or more ingredients intended to facilitate mixing with the final silicone composition. It may in particular be a question of adapting the viscosity, in order to bring it closer to that of the constituent or of the mixture of constituents of the final silicone material in which the additive is provided. It may in particular be a silicone oil or gum having a viscosity compatible with POS A or B. Depending on the silicone composition, the person skilled in the art is perfectly capable of choosing a suitable oil or gum, in particular suitable in terms of viscosity, to dilute the inhibitor-catalyst composition previously obtained. According to a particular method, an oil or gum chosen from POS A or B described with regard to the silicone composition is used.

  Preferably, the additive obtained according to mode 1 or mode 2, after possible dilution in an oil or gum, comprises from 0.001 to 10%, better still from 0.01 to 1% by weight of platinum metal.

  Preferably, the additive thus obtained (mode 1 or 2) is a simple pasting intended to be then added to the silicone composition proper. In other words, this additive constitutes a fraction of the final single-component silicone composition. Thus, according to an advantageous embodiment, the additive is based on one of the constituents of this composition and in particular based on POS A. The additives or catalytic units obtained by the use of the preparation methods which have just been described also constitute objects of the present invention. They preferably comprise at least one inhibitor of formula (I), (II), (111), (VIII) or (IX) and a catalyst according to the invention, in particular a platinum / unsaturated siloxane solution, in particular a platinum / vinylsiloxane solution, in particular obtained by reaction between a platinum halide and an unsaturated organosilicon material such as an unsaturated silane or an unsaturated siloxane, eg the Karstedt solution or complex.

  The invention particularly relates to such an additive, in which the catalyst + inhibitor assembly represents 0.001. to 40% by weight, preferably from 0.01 to 30%, more preferably from 0.1 to 20%.

  The subject of the present invention is also a silicone composition crosslinkable by hydrosilylation, comprising at least one PolyOrganoSiloxane (POS) having 20 ethylenic and / or acetylenic unsaturation (s), at least one hydrogenated polyorganosiloxane B ( hereinafter POS B), a hydrosilylation catalyst and an inhibitor of formula (I), (II) or (111).

  By definition, throughout this description, when it is said that a silicone composition or an additive or catalytic unit comprises such or such an inhibitor of formula (1), (II), (111), (VIII) or (IX), it means free inhibitor, inhibitor complexed with the catalyst, or a mixture of these two species.

  According to the preferred embodiment of the invention, the composition comprises an additive or catalytic unit according to the invention, preferably provided in the form of a mash prepared according to one of the modes of preparation 1 and 2 defined above.

  In a less preferred variant, the catalyst and the inhibitor are added separately to the silicone composition. It is then preferable to add them in POS A or in a composition containing POS A and one or more other ingredients, with the exception of POS B. POS B is incorporated after a careful mixing of POS A, the catalyst and of the inhibitor and advantageously after a certain lag time. For its incorporation, the inhibitor may advantageously be in solution in a vinylsiloxane.

  The invention is aimed equally at polyaddition silicone compositions which can be vulcanized at room temperature PRTV (and whose crosslinking can be accelerated when hot) as well as those known as hot vulcanizable elastomers EVC.

  They are well known to those skilled in the art, who can refer, for example, to patents US-A-3,220,972, US-A-3,284,406, US-A-3,346,366, USA-3,697,473 and US -A-4 340 730.

  As is known per se, the POS A can in particular be formed of siloxyl units of formula: a bSi (4-ab) (IV) in which Y is a C2-C6 alkenyl, preferably vinyl, Z is a hydrocarbon group monovalent having no unfavorable action on the activity of the catalyst, Z is generally chosen from alkyl groups having from 1 to 8 carbon atoms inclusive such as methyl, ethyl, propyl and 3.3, 3trifluoropropyl groups and aryl groups such as xylyl, tolyl and phenyl, a is 1 or 2, 20 b is 0, 1 or 2 and a + b is between 1 and 3, possibly all the other units being units of average formula: ZSio4-c (V) in which Z has the same meaning as above and ca a value between 0 and 3.

  As is known per se, POS B can in particular be formed of siloxyl units of formula: HdWe SiO 4-of 2 (VI) in which W is a monovalent hydrocarbon group having no unfavorable action on the activity of catalyst and corresponding to the same definition as Z, d is 1 or 2, e is 0, 1 or 2, d + has a value between 1 and 3, possibly all the other units being units of average formula WgSiO4-g ( Vil) in which W has the same meaning as above, g has a value between 0 and 3.

  These POS A & B are for example respectively a polyorganovinylsiloxane and a polyorganohydrogensiloxane. The organic substituents other than the vinyl and hydrogen reactive groups are, for example, methyls or cyclohexyls. The hydrogens and the vinyls are carried by siloxy units M = [R3SiO-] and / or D = [- (R) 2SiO-] and / or T = [- (R) SiO-]. These hydrogenated or vinylized units M, D each comprise one or more Hs or vinyls, preferably only one.

  The number of SiH or SiVi units per molecule is preferably greater than or equal to 2. This can in particular 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 POS B are polymethylhydrogensiloxanes with ends - Si (CH3) 3 and polydimethylsiloxanes with ends - Si (CH3 ) 2H, methylhydrogenodimethylsiloxane copolymers with -Si (CH3) 2H ends, methylhydrogenomethyloctylsiloxane copolymers, and methylhydrogenocyclosiloxane polymers In general, POS A & B have an average molecular weight between 1.102 and 1.107 (g / mol).

  For POS A, this includes in particular, in terms of dynamic viscosity at 25 C: o in the case of silicone compositions which can be vulcanized hot (EVC) by polyaddition, POS A having in particular a viscosity at least equal to 5.105 mPa.s , preferably between 1.106 and 1.107 mPa.s, and even more, 30 o in the case of silicone compositions which can be vulcanized hot by polyaddition of the liquid silicone elastomer (LSR) type, POS A having in particular a viscosity preferably of 1.104 and 5.105 mPa.s, and o in the case of silicone compositions vulcanizable at room temperature (vulcanization being accelerated while hot) by polyaddition or RTV, POS A having in particular a viscosity of between 100 and 104 mPa.s, preferably between 1000 and 5000 mPa.s. POS B generally have a viscosity of between 10 and 10,000 mPa.s, preferably between 50 and 1,000 mPa.s.

  According to a preferred embodiment of the invention, the silicone compositions concerned are POSs which can be vulcanized hot (EVC) by polyaddition and in which the POS A can in practice have a viscosity at 25 C of eg 1.106 to 5.106 mPa.s and the POS B from 10 to 5000 mPa.s, in particular from 50 to 1000 mPa.s (eg 300 mPa.s).

  The viscosity is measured using a BROOKFIELD viscometer according to the indications of standard AFNOR NFT 76 106 of May 1982.

  All the viscosities referred to in the present description correspond to a quantity of dynamic viscosity at 25 C known as "Newtonian", that is to say the dynamic viscosity which is measured, in a manner known per se, at a gradient sufficiently low shear speed so that the viscosity measured is independent of the speed gradient.

  According to a particular form of the invention, to the composition comprising POS A and B and the catalytic assembly according to the invention, an inhibitor of formula (I), (II) or (111) can be added, in particular in solution in a vinylsiloxane, and / or another crosslinking inhibitor, for example of formula (VIII) or (IX), an acetylenic alcohol (FR-A-2 372 874, FR-A-1 528 464), a compound of maleate type (US-A-4,256,870 and US-A-4,530,989) or an acetylene dicarboxylate compound (US-A-4,504,645 and US-A-4,347,346).

  The silicone compositions of the invention may further comprise conventional functional additives. As families of usual functional additives, there may be mentioned: a fillers, ò POS hydroxylated oils useful as compatibilizers, * adhesion promoters, * adhesion modulators, X thermal behavior additives X additives for increasing consistency * pigments, ò additives for thermal resistance, resistance to oils, to fire (for example metal oxides). The charges possibly provided are preferably mineral. They can in particular be siliceous.

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

  The reinforcing siliceous fillers are chosen from collodal silicas, combustion and precipitation silica powders or their mixtures. These powders have an average particle size generally less than 0.1 μm and a BET specific surface area greater than 50 m 2 / g, preferably between 150 and 350 m2 / g.

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

  With regard to non-siliceous mineral materials, they can act as a semi-reinforcing or tamping mineral filler. Examples of these non-siliceous fillers which can be used alone or as 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 fillers have a particle size generally between 0.001 and 300 vlm and a BET surface area of less than 100 m2 / g.

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

  The charges can be treated with any suitable product.

  In terms of weight, it is preferred to use an amount of filler between 10 and 50% by weight, preferably between 20 and 40% by weight relative to all of the constituents of the composition.

  More generally, quantitatively, the compositions according to the invention refer to standard proportions in the technical field under consideration, knowing that the intended application must also be taken into account.

  The subject of the invention is also a process for the preparation of a single-component silicone composition crosslinkable by hydrosilylation, comprising at least one PolyOrganoSiloxane (POS) having ethylenic and / or acetylenic unsaturation (s), at least one hydrogenated polyorganosiloxane B (hereinafter POS B), at least one hydrosilylation catalyst and at least one inhibitor of formula (1), (II), (III), (VIII) and / or (IX), process in which an additive or catalytic assembly according to the invention is added to POS A, to POS B or to a mixture of POS A and B, that is to say a mash formed from the premix of the inhibitor and 15 of the catalyst.

  According to a first embodiment of the invention, an additive prepared according to mode 1 described above (with or without dilution) is added. The additive is therefore derived from the dispersion of the inhibitor in a solution of the catalyst in an unsaturated silane or siloxane, preferably vinylsiloxane.

  According to a second embodiment, an additive prepared according to mode 2 described above (with or without dilution) is added. The additive is then obtained from the mixture of the inhibitor in a silicone oil or gum at a temperature higher than the melting or softening temperature of the inhibitor, then addition of the catalyst.

  The additive can be added before, during or after addition of the other ingredients such as mineral filler, crosslinking inhibitor, hydroxylated POS oil, or other usual functional additives such as those described above.

  The additives or catalytic units according to the invention can be easily mixed in this silicone composition. The various mixing means usually used in the silicone industry can be used, and in particular arm mixers and cylinder mixers when the viscosity requires it, in particular in the case of EVCs. The mixing operation is continued to obtain an optimal dispersion of the additive or catalytic unit. Those skilled in the art are capable of determining the optimal conditions. A further subject of the invention is the monocomponent silicone compositions which can be obtained by implementing the preparation process which has just been described, compositions which are characterized in particular by a remarkably fine and homogeneous dispersion of the catalyst / inhibitor couple . Another object of the invention is constituted by a hydrosilylation process 10 of one or more POS A using one or more POS B, characterized in that it consists in using a silicone composition such as defined above and to heat it to the crosslinking temperature, generally between 50 and 2000 ° C., more particularly between 100 and 1500 ° C. Depending on the composition, the person skilled in the art has no difficulty in determining the temperature optimal for initiating hydrosilylation.

  The relative amount of unsaturated compound and compound having an Si-H unit can be controlled so as to ensure the reaction of all unsaturations with Si-H bonds.

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

  According to the invention, the hydrosilylation reaction is carried out in the presence of a catalytic amount of the catalyst according to the invention. By catalytic amount means less than a molar equivalent of platinum relative to the amount of unsaturations present in the reaction medium.

  In general, it suffices 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 units. .

  POS A & B, catalyst, compounds of formula (1), (II), (III) (VMII) 30 and (IX), as well as other conventional additives such as fillers, are perfectly available accessible amenities to the skilled person.

  The compounds of formula (I,) (II) or (III) can be obtained in the usual manner by reaction between (i) a dihalogenated compound XRX (X for a halogen atom), R having the meaning given above with regard to formulas (1), (II) and (III), and (ii) an excess of PCI3, then by reaction of the compound obtained in previous step 5 with the 4 alcohol molecules R'OH, making it possible to form the groups R1 to R4 of formulas (1), (II) and (Ill). The product obtained can then be purified using conventional techniques known to those skilled in the art.

  The invention will now be described using nonlimiting examples.

EXAMPLES

  Example 1: Preparation of a catalytic solution having an Inhibitor (111) / Pt ratio = 0.75 (i.e. P / Pt = 1.5) g of a Karstedt platinum solution containing 12.6% Pt by weight 15 (6.46 mmol of Platinum) are placed in a flask fitted with a magnetic stirrer. 5.01 g (4.85 mmol or 0.75 equivalent) of the Inhibitor (III) according to the invention are added to the preceding solution with stirring.

  At the end of the addition, the reaction mixture is kept stirring for a few minutes. A catalytic solution is obtained containing 8.4% Platinum by weight. This clear, homogeneous and easily handled solution is used in the following examples.

  NMR analysis of this reaction mixture shows the complete disappearance of the Karstedt catalyst.

  Example 2: Preparation of a catalytic assembly having an Inhibitor (IV) / Pt = 1.5 ratio (i.e. P / Pt = 1.5) g of a Karstedt platinum solution containing 12.6% Pt by weight (6.46 mmol of Platinum) are placed in a flask fitted with a magnetic stirrer.

  6.27 g (9.69 mmol or 1.5 equivalent) of an inhibitor according to US-A-6 300 455 are added to the preceding solution with stirring. This inhibitor of formula (IX) above corresponds more precisely to formula (X) below t-Bu t-Bu t-Bu P -O t-Bu t-Bu t-Bu At the end of the addition , the reaction mixture is heterogeneous. It remains heterogeneous even after several minutes of agitation. After 3 hours of stirring, the reaction mixture becomes heterogeneous in white color. Stopping the agitation causes the white solid to settle at the bottom of the bottle.

  NMR analysis of this reaction mixture shows the complete disappearance of the Karstedt catalyst.

  Example 3: Composition according to the invention (all parts are given by weight). A / Preparation In a kneader with a Z-arm, a base EVC 1 is prepared by mixing for 2 hours at room temperature (23 C): With 100 parts of a vinylized polydimethylorganosiloxane containing in the chain 720 ppm of groups Vi, and having a viscosity of 5 million mPa.s at 25 C, has 33 parts of surface treated combustion silica, with a specific surface 20 of 60 m2 / g, 13 parts of an untreated silica with a specific surface of 150 m2 / g 6 parts of a compatibilizing agent which is a hydroxylated polyorganosiloxane oil. To this preparation, are added on cylinders: * 0.604 part of a polydimethylorganosiloxane oil containing 30% by weight of groups - SiH, and having a viscosity of 30 mPa.s at 250C * 2.5 ppm of platinum metal supplied in the form of the catalytic assembly of

Example 1.

  * 6.25 ppm of inhibitor (III) in solution in a vinylsiloxane.

  B / Characterization of the composition: * A fraction of the homogeneous mass obtained is used to measure the rheometric properties of the silicone elastomer during the vulcanization at 1400 ° C. of the polyorganosiloxane composition.

  * This characterization is carried out according to standards NF T43015 and ISO 6502. A test piece of catalyzed elastomer is compressed in a sealed chamber under a given pressure and at a given temperature. The chamber is formed by two half-chambers, one of which is subjected to low linear or rotary (disc) oscillations. This action produces in the test tube an alternative sinusodal deformation, linear or in torsion, and a force or a sinusodal shear torque which depend on the rigidity (shear modulus) of the elastomer. The rigidity of the test piece increases as the vulcanization or polyaddition reaction takes place. The measurement as a function of the time of the torque necessary for the oscillation of the disc makes it possible to obtain at the end of the measurement the vulcanization characteristics of the elastomer.

  Rheometric properties recorded at 140 C: - ts2: toasting time (Cmin + 2 points) corresponding to the vulcanization time - t50 time required to obtain 50% of the value of Cmax - t90 time required to obtain 90% of the value of Cmax - Cmin: minimum elastic torque applied (also called S'Mini) - Cmax: maximum elastic torque applied (also called S 'Maxi) - Vmax: maximum vulcanization speed reached.

  characteristics values ts2 20 s t50 47 s t90 389 s Cmin 1 dNm Cmax 10.7 dNm Vmax 12.6 dNm / min Pot life After 4 weeks of aging at room temperature, the mixture is still not crosslinked.

  All of these results show that the new claimed catalytic assembly is characterized by great ease of use and efficient catalytic properties (measured by rheometry).

  Example 4: In-situ preparation, by a hot process, of an additive based on a silicone matrix, Karstedt platinum and the inhibitor (III).

  4a / In a hand mixer, 0.261 g of inhibitor (III) is added to g of an EVC 2 base of hardness 35. After mixing for 10 minutes, the temperature of the reaction medium is brought to at least 1000 ° C., temperature higher than the softening temperature 75-95 C of the inhibitor (Ill). After mixing for 10 minutes, the reaction medium is allowed to cool to 250 C. An observation of the mixture does not reveal the presence of agglomerates in the elastomer matrix.

  4b / 0.375 g of Karstedt catalyst (platinum with zero oxidation degree in solution in vinyl silicone oil) (10% by mass of platinum) is then added, either on a cylinder mixer or in an arm mixer. Note: for all of Examples 4 to 10, a 25 EVC 2 base was used consisting of: - 50 parts of vinylated polydimethylorganosiloxane containing in the chain 720 ppm of vinyl groups and having a viscosity of 5 million mPa.s to 25 C, 50 parts of vinylated polydimethylorganosiloxane containing in the chain 120 ppm of vinyl groups and having a viscosity of 5 million mPa.s at 25 C, 5 - 30 parts of surface-treated combustion silica, with a specific surface of 55 m2 / g, - 1.22 parts of a compatibilizing agent which is a hydroxylated polyorganosiloxane oil.

  Comparative Example 5: Preparation on a cylinder mixer, by a cold process, of an additive based on a silicone matrix, Karstedt platinum and inhibitor (III).

  1.305 g of inhibitor (111) in powder form in 500 g of EVC 2 base of hardness 35 are added to a cylinder mixer. 1.75 g of Karstedt catalyst are added dropwise after incorporation.

  Comparative Example 6: Preparation in an arm mixer, by a cold process, of an additive based on a silicone matrix, Karstedt platinum and inhibitor (III).

  The same type of additive, described in Example 5, was produced using an arm mixer.

  6a / 1.048 g of powdered inhibitor are added to 400 g of EVC 2 base of hardness 35. The mixing is continued for 20 minutes.

  6b / 1.5 g of Karstedt catalyst are then added to the reaction medium.

  Examples 7 and 8: Evaluation of the various additives prepared according to Examples 4 and 6 The various additives described in Examples 4 and 6 were tested in an EVC formulation for the one-component application of polyaddition.

  The composition of this EVC formulation is as follows: for each 100 g of an EVC 1 base according to Example 3, 0.94 parts of oil at -SiH are added, using a cylinder mixer. 440 meq - SiH / 100 g of oil, viscosity 250 mPa.s). After incorporation, then the completion of 15 passages between the two cylinders (improvement of the dispersion of the additives), 0.037 parts of an additive composed of the base EVC 2 of hardness 35 and inhibitor (III) are added according to the 5 examples 4a and 6a. After incorporation, then the production of 15 passages of the composition between the two cylinders, 0.267 part of the additive composed of the EVC base, inhibitor (III) and Karstedt platinum (examples 4 and 6 above) is added. The amount of platinum is 1 ppm. The passages between the two cylinders are also carried out. The results in terms of raw appearance of the 10 formulations produced, of the kinetic characteristics and of the evolution of the formulation after 3 months at 250 ° C. are reported in Table 2.

  Example 9: Stability of the additives prepared according to Example 4 In order to follow the stability of these additives and the kinetics of complexation between the Karstedt platinum, the additives prepared according to Example 4 were evaluated as a function of time. Through an EVC formulation for the one-component polyaddition application identical to that described in Example 7, the complexation of platinum by the inhibitor and the stability of this additive were followed, through measurements determined by rheometry ( table 3).

  Discussion of the results obtained with Examples 4 to 9 The additives prepared cold from the inhibitor (III) and Karstedt platinum (Examples 5 and 6) present agglomerates whose average diameters vary according to the type of tool used (table 1). As a result, these additives are not as efficient as the hot prepared additive according to Example 4 (Table 2). These monocomponent EVC formulations additivated according to Examples 5, 6 however remain stable after three months of aging. For the additive prepared according to Example 4, there is no problem d with the incorporation of the inhibitor, then of Karstedt platinum. The raw additive is homogeneous. There are no faults (table 1). The one-component EVC formulation added with these additives is stable after 3 months of aging and no deterioration in the quality of the parts is observed (Table 2).

  Monitoring, by rheometry, the complexation between the inhibitor and the Karstedt platinum shows that this complexation is extremely rapid. The values obtained at 0 days are of the same order as those obtained after 18 days. 5 Moreover, the values over this period are homogeneous, which indicates a stability of the additive (Table 3).

  Conclusion: The implementation of the hot process makes it possible to obtain additives in which the 10 active species are perfectly dispersed. The good quality of these additives goes hand in hand with good quality and good stability of the final single-component EVC formulations.

  Table 1: characteristics, raw, of the additives produced example 4 5 6 Inhibitor System (Ill), Karstedt Platinum Preparation of Mixer to Mixer to Mixer to additive Work arm cylinders arm Phase No No No No incorporation problem problem problem Appearance of the additive after homogeneous Heterogeneous, Heterogeneous, production of agglomerates agglomerates with a diameter of 0.5 to 0.8 mm 0.3 to 0.5 mm Table 2: characteristics of the one-component EVC formulations according to the examples Example 7 8 Additive engaged Example 4 Example 6 Characteristics Inhibitor (111), Inhibitor (111i), Karstedt platinum Karstedt platinum Arm mixer Arm mixer Seek of the parts after cooking 8 min No defects, Cross-linked homogeneous areas below 140 ° C , presence of gels Characteristics ts2 30 30 rheological t50 52 55 t90 428 438 Cmin 1.59 1.82 Cmax 9.15 9.02 Vmax 82 71 Evolution of the raw formulation after Good Good 3 months replastification replastification Table 3: Evolution of the additive prepared according to Example 4 Evaluation of the corresponding single-component EVC formulations Age of the additive 0d ld 2d 5d 6d 18d

from example 4

  ts 2 (sec.) 24 25 24 23 25 26 t50 (sec.) 53 51 46 46 57 54 t90 (sec.) 412 426 411 403 439 410 Cmin (dNm) 1.04 0.99 0.97 0.93 0.97 1.02 Cmax (dNm) 8.46 7.88 7.47 7.70 8.02 8.20 Vmax 8.6 8.8 7.47 7.70 8.02 8.3 (dNm / Min) Example 10: Preparation of catalyst-inhibitor complexes (111) or (X) Catalyst 1: To 3.6 g of Karstedt catalyst at 12% by weight of platinum in divinyltetramethyldisiloxane (DVTMS) are added to the spatula with stirring vigorous magnetic 1.32 g of the compound (III) (so that the P / Pt molar ratio = 1.2). After a few minutes, a homogeneous fluid solution (Cl) 5 which is easy to handle is obtained. It contains 7.65% platinum by weight and is used directly in the examples which follow.

  Catalyst 2 To 4.3 g of Karstedt catalyst at 10% by weight of platinum in the DVTMS 10 are added to the spatula with magnetic stirring 1.7 g of the compound (X) (so that the molar ratio P / Pt = 1.2). After a few minutes, a heterogeneous reaction mixture (C2) is obtained. It contains 7.2% platinum by weight and is used directly in the examples which follow.

  Example 11: Evaluation of the quality of inhibition provided by C1 and C2 A reaction system is prepared by mixing 20 grams of an organovinylpolysiloxane of viscosity 230 mPa.s and containing 0.61% of vinyls by weight, the catalyst mixture C1 or C2 so as to obtain 80 ppm by weight of platinum in the final mixture; then 5.4 grams of an organohydrogensiloxane 20 with a viscosity of 300 mPa.s and containing 0.17% by weight of hydrogen are added.

  This final reaction mixture is homogenized by stirring for 5 minutes.

  To assess the quality of the inhibition, the gel time tgel corresponding to the setting time of the reaction mixture is measured at room temperature. The comparative reactivity of the two systems is evaluated by DSC 25 (Differential Scanning Calorimetry).

  Mixture tgel DSC Catalyst tpic (C) tendset-tonset (C) AH (kJ / mol) C1> 24 hours 104 12 20.7 C2> 24 hours 109 19 20.4 Comparative example 12: A reaction system is prepared by mixing 20 grams of an organovinylpolysiloxane of viscosity 230 mPa.s and containing 0.61% vinyl by weight, the amount of organophosphorus inhibitor (JIl) or (X) required to obtain a P / Pt ratio of 1.2 , then the Karstedt catalyst (14.3% platinum solution in the DVTMS) so as to obtain 80 ppm by weight of platinum in the final mixture. This mixture is stirred for 10 minutes at room temperature, then 5.4 grams of an organohydrogensiloxane of viscosity 300 mPa.s and containing 0.17% by weight of hydrogen are added. This final reaction mixture is homogenized by stirring for a few minutes.

  To assess the quality of the inhibition, the gel time corresponding to the setting time of the reaction mixture is measured at room temperature. Inhibitor tgel (Ill) <5 minutes (X) <5 minutes Examples 11 and 12 show that * to obtain effective inhibition, it is preferable to incorporate the platinum in a pre-complexed form rather than carrying out this complexation directly in the final reaction mixture.

  * The type III inhibitor leads to homogeneous catalytic systems in the DVTMS which greatly facilitates their use. The reactivities of the two catalytic systems are however comparable. It should be understood that the invention defined by the appended claims is not limited to the particular embodiments indicated in the description above, but encompasses the variants which do not emerge nor neither the scope nor the spirit of the present invention.

Claims (11)

  1. Process for the preparation of a single-component silicone composition, crosslinkable by hydrosilylation, comprising at least one polyorganosiloxane 5 (POS) carrying ethylenic and / or acetylenic unsaturation (s), at least one polyorganohydrogensiloxane ( POS) B, a hydrosilylation catalyst and an inhibitor which is an organophosphorus compound inhibiting the action of the catalyst at ambient temperature, process in which is added, in POS A, in POS B or in a mixture of POS A and B , an additive formed from the premix of the hydrosilylation catalyst and the inhibitor, and in which the inhibitor corresponds to the following formula (I) R10 oR? R'O OR3 \ P- R _P R20 / \ OR4 in which i 2 3 4 R, R, R, R and R4, identical or different, represent a linear, branched or cyclic alkyl radical, or a substituted aryl radical or no, in particular: i. a linear or branched alkyl radical, in particular having from 2 to 30 carbon atoms (C), preferably from 2 to 12 C, ii. an alkyl radical comprising one or more rings, in particular 1 or 20 2, a cycle which may in particular have from 4 to 14 C, preferably from to 8 C, or iii. an aryl or alkylaryl radical, comprising one or more adjoining or non-adjoining aromatic rings, in particular 1 or 2 rings, a cycle possibly comprising from 4 to 14 C, preferably from 6 to 8 C, optionally substituted by 1 or several, in particular from 1 to 2, linear or branched alkyl (s), in particular having from 1 to 12 C, preferably from 4 to 12 C, or else the inhibitor corresponds to formula (VIII) P (OR) 3 in which R is an alkylaryl radical having in particular from 7 to 31 carbon atoms, preferably substituted phenyl radicals.   2. Method according to claim 1, characterized in that in formula (1) R is a cyclic alkyl radical or an alryl radical, preferably biphenyl.   3. Method according to claim 1 or 2, characterized in that in formula (I) that R, R2, R3 and R4 are cyclic alkyl radicals, aryl radicals or alkylaryl radicals, preferably substituted phenyl radicals.   4. Method according to claim 1, characterized in that the inhibitor corresponds to the formula (II): / \ 0 \ -P r \ R5. R5 in which the radicals R5, identical or different, preferably identical, are linear or branched alkyls, having in particular from 1 to 12 15 C, preferably from 4 to 12 C, and preferably represent t-Bu.   5. Method according to claim 1, characterized in that the inhibitor corresponds to formula (IX): P O -3   in which R1, R, R3, R4, R5, identical or different, represent H, an aliphatic radical, linear or branched, saturated with formula CnH2n + 1 or unsaturated with formula CmH2ml, or a radical with formula CnF2n + 1, with n = 1 to 15, and m = 3 to 15, all of these radicals not being able to represent all together H. 6. Method according to claim 12, characterized in that the inhibitor is: t-Bu t-Bu t- Bu o t-Bt 15 20 7. Method according to any one of claims 1 to 6, characterized in that the catalyst is an unsaturated platinum / siloxane complex, especially platinum / vinyl siloxane, preferably a Karstedt complex.   8. Method according to any one of claims 1 to 7, characterized in that the additive is derived from the dispersion of the inhibitor in a solution of the catalyst in a silane or an unsaturated siloxane, preferably vinylsiloxane. 9. Method according to claim 8, characterized in that the additive is derived from the dispersion of the inhibitor in a catalytic solution of platinum / unsaturated siloxane, in particular platinum / vinylsiloxane, preferably Karstedt solution. 10. Process according to any one of claims 1 to 7, characterized in that the additive is obtained from the mixture of the inhibitor in a silicone oil or gum at a temperature higher than the melting or softening temperature of the inhibitor, then addition of catalyst.   1 1. Process according to claim 10, characterized in that the silicone oil or gum is an oil or gum comprising ethylenic and / or acetylenic unsaturation (s), preferably an oil or a gum vinylated, preferably a part of POS A used in the composition of the one-component silicone composition.   12. Process for the preparation of an additive or catalytic assembly comprising a metal hydrosilylation catalyst and an organo-phosphorus compound inhibiting the catalytic action of the catalyst at room temperature, process in which the organo-phosphorus compound is added in an oil or silicone gum, preferably an oil or silicone gum carrying ethylenic and / or acetylenic unsaturation (s), more preferably vinyl (s), and the dispersion of the organo-phosphorus compound in this oil or silicone gum is carried out at a temperature above the melting or softening temperature of the organophosphorus compound, then the catalyst is mixed in the composition obtained above.   13. The method of claim 12, characterized in that the organo-phosphorus compound is first dispersed in oil or gum, then the mixture is heated to a temperature above the melting or softening temperature of the organo-compound phosphorus.   14. Process according to claim 12 or 13, characterized in that the catalyst is mixed with the composition formed from the silicone oil or gum and from the organophosphorus inhibitor, preferably after this composition has cooled, in particular at the temperature room. 15. Process for preparing an additive or catalytic assembly comprising a metal hydrosilylation catalyst and an organophosphorus compound inhibiting the catalytic activity of the catalyst at room temperature, in which the catalyst is in the form of a solution or dispersion of the metal catalyst in an unsaturated siloxane, preferably vinylsiloxane, characterized in that the organo-phosphorus compound is mixed in this metal catalyst solution.   16. Process according to any one of claims 12 to 15, characterized in that the catalyst is an unsaturated platinum / siloxane solution, in particular platinum / vinyl siloxane and preferably the Karstedt solution.   17. Process according to any one of claims 12 to 16, characterized in that the organophosphorus compound is chosen from the organophosphorus compounds of formula (I): RiO OR3 \ PR _P R20 / \ OR4 in which: R , R1, R2, R3 and R4, identical or different, represent a linear, branched or cyclic alkyl radical, or a substituted or unsubstituted aryl radical, in particular: iv. a linear or branched alkyl radical, in particular having from 2 to 20 carbon atoms (C), preferably from 2 to 12 C, v. an alkyl radical comprising one or more rings, in particular 1 or 2, a cycle which may in particular have from 4 to 14 C, preferably from to 8 C, or vi. an aryl or alkylaryl radical, comprising one or more adjoining or non-adjoining aromatic rings, in particular 1 or 2 rings, a cycle possibly comprising from 4 to 14 C, preferably from 6 to 8 C, optionally substituted by 1 or several, in particular from 1 to 2, linear or branched alkyl (s), in particular having from 1 to 12 C, preferably from 4 to 12 C, or else the inhibitor corresponds to formula (VIII) P (OR) 3 in which R is an alkylaryl radical having in particular from 7 to 31 carbon atoms, preferably substituted phenyl radicals.   S 18. Process according to claim 17, characterized in that the inhibitor corresponds to the following formula (IX) R1 2 P --OX R3 R5 / R4 2 3 in which R1, R2R, R3,, R R5, identical or different, represent H, an aliphatic radical, linear or branched, saturated with formula CnH2n + 1 or unsaturated 10 with formula CmH2m-1, or a radical with formula CnF2n + 1, with n = 1 to 15, and m = 3 to 15 , All of these radicals not being able to represent all together H. 19. The method according to claim 18, characterized in that the inhibitor corresponds to the following formula (X) t-Bu t-Bu t-Bu PO t-Bu x O i5o   t-Bu 't-Bu 20. Additive comprising a hydrosilylation catalyst and an organophosphorus compound inhibiting the catalytic action of the catalyst at room temperature, capable of being obtained by implementing the method 20 according to any one from claims 12 to 19.