NOVEL SILICONE COMPOSITION CROSSLINKING CATALYSTS

Abstract

A crosslinked silicone material Y obtained by heating to a temperature of between 70 and 200° C., a crosslinkable composition X including an organopolysiloxane compound A containing, per molecule, at least two C.sub.2-C.sub.6 alkenyl radicals bonded to silicon atoms; an organohydrogenopolysiloxane compound B containing, per molecule, at least two hydrogen atoms bonded to an identical or different silicon atom; a catalyst C of formula [Ni(L.sup.1).sub.2] where Ni represents nickel at degree of oxidation II; L.sup.1 which may be identical or different, represents a β-dicarbonylato anion or the enolate anion of a β-dicarbonylated compound; optionally an adhesion promoter D; and optionally a charge E.

Claims

1. Crosslinked silicone material Y obtained by heating to a temperature of between 70 and 200° C., preferably between 80 and 150° C., and more preferably between 80 and 130° C., a crosslinkable composition X comprising: at least one organopolysiloxane compound A comprising, per molecule, at least two C.sub.2-C.sub.6 alkenyl radicals bonded to silicon atoms, at least one organohydrogenopolysiloxane compound B comprising, per molecule, at least two hydrogen atoms bonded to an identical or different silicon atom, at least one catalyst C which is a complex corresponding to the following formula:
[Ni(L.sup.1).sub.2] in which: the symbol Ni represents nickel at degree of oxidation II, the symbols L.sup.1, which may be identical or different, represent a ligand which is a β-dicarbonylato anion or the enolate anion of a β-dicarbonylated compound, optionally at least one adhesion promoter D and optionally at least one charge E.

2. Crosslinked silicone material Y according to claim 1, wherein the catalyst C is present in a content ranging from 0.001 to 10% molar of nickel per number of moles of C.sub.2-C.sub.6 alkenyl radicals bonded to silicon atoms of the organopolysiloxane compound A, preferably between 0.01 to 7%, and more preferably between 0.1 to 5%.

3. Crosslinked silicone material Y according to claim 1, wherein the composition X is free of catalyst based on platinum, palladium, ruthenium or rhodium.

4. Crosslinked silicone material Y according to claim 1, wherein the ligand L.sup.1 is an anion derived from a compound of formula (1):
R.sup.1COCHR.sup.2COR.sup.3  (1) in which: R.sup.1 and R.sup.3, which may be identical or different, represent a C.sub.1-C.sub.30 linear, cyclic or branched hydrocarbon radical, an aryl containing between 6 and 12 carbon atoms, or a —OR.sup.4 radical with R.sup.4 which represents a C.sub.1-C.sub.30 linear, cyclic or branched hydrocarbon radical, R.sup.2 is a hydrogen atom or a hydrocarbon radical, preferably alkyl, comprising from 1 to 4 carbon atoms; with R.sup.1 and R.sup.2 can be connected in order to form a C.sub.5-C.sub.6 cycle, and R.sup.2 and R.sup.4 can be connected in order to form a C.sub.5-C.sub.6 cycle.

5. Crosslinked silicone material Y according to claim 4, wherein the compound of formula (1) is chosen from the group comprising β-diketones: 2,4-pentanedione (acac); hexanedione-2,4; heptanedione-2,4; heptanedione-3,5; ethyl-3 pentanedione-2,4; methyl-5 hexanedione-2,4; octanedione-2,4; octanedione-3,5; dimethyl-5,5 hexanedione-2,4; methyl-6 heptanedione-2,4; dimethyl-2,2 nonanedione-3,5; dimethyl-2,6 heptanedione-3,5; 2-acetylcyclohexanone (Cy-acac); 2,2,6,6-tetramethyl-3,5-heptanedione (TMHD); 1,1,1,5,5,5-hexafluoro-2,4-pentanedione (F-acac)]; benzoylacetone; dibenzoyl-methane; 3-methyl-2,4-pentadione; 3-acetyl-pentane-2-one; 3-acetyl-2-hexanone; 3-acetyl-2-heptanone; 3-acetyl-5-methyl-2-hexanone; benzoylstearoylmethane; benzoylpalmitoylmethane; octanoylbenzoylmethane; 4-t-butyl-4′-methoxy-dibenzoylmethane; 4,4′-dimethoxy-dibenzoylmethane and 4,4′-di-tert-butyl-dibenzoylmethane, and preferably from ?-diketones 2,4-pentanedione (acac) and 2,2,6,6-tetramethyl-3,5-heptanedione (TMHD).

6. Crosslinked silicone material Y according to claim 1, wherein the catalyst C is chosen from the complexes [Ni(acac).sub.2], [Ni(TMHD).sub.2], [Ni(ketoester).sub.2] and [Ni(Rhodiastab 50).sub.2], where “acac” means the anion derived from the compound 2,4-pentanedione, “THMD” means the anion derived from the compound 2,2,6,6-tetramethyl-3,5-heptanedione, “ketoester” means the anion derived from a methyl ester of acetoacetic acid and “Rhodiastab 50” means a mixture of anions derived from the compound benzoylstearoylmethane, and of anions derived from the compound benzoylpalmitoylmethane.

7. Crosslinked silicone material Y according to claim 6, wherein the organopolysiloxane A comprises: (i) at least two siloxyl units (A.1), which may be identical or different, of the following formula: $\begin{array}{cc}{W}_a.Math.Z_b.Math.{\mathrm{SiO}}_{\frac{d-\left(a+b\right)}{2}}& \left(A.Math.\mathrm{.1}\right)\end{array}$ in which: a=1 or 2, b=0, 1 or 2 and a+b=1, 2 or 3; the symbols W, which may be identical or different, represent a C.sub.2-C.sub.6 linear or branched alkenyl group, and the symbols Z′, which may be identical or different, represent a monovalent hydrocarbon group having from 1 to 30 carbon atoms, and preferably chosen from the group consisting of alkyl groups having from 1 to 8 carbon atoms and aryl groups containing between 6 and 12 carbon atoms, and more preferably chosen from the group consisting of a methyl, ethyl, propyl, 3,3,3-trifluoropropyl, xylyl, tolyl and phenyl radical, (ii) and optionally at least one siloxyl unit of the following formula: $\begin{array}{cc}{Z}_a^1.Math.{\mathrm{SiO}}_{\frac{4-a}{2}}& \left(A.Math.\mathrm{.2}\right)\end{array}$ in which: a=0, 1, 2 or 3, the symbols Z.sup.2, which may be identical or different, represent a monovalent hydrocarbon group having from 1 to 30 carbon atoms and preferably chosen from the group consisting of alkyl groups having from 1 to 8 carbon atoms inclusive and aryl groups containing between 6 and 12 carbon atoms, and more preferably chosen from the group consisting of a methyl, ethyl, propyl, 3,3,3-trifluoropropyl, xylyl, tolyl and phenyl radical.

8. Crosslinked silicone material Y according to claim 1, wherein the organohydrogenopolysiloxane compound B comprises at least three hydrogen atoms per molecule directly bonded to an identical or different silicon atom.

9. Crosslinked silicone material Y according to claim 1, wherein the organohydrogenopolysiloxane compound B is an organopolysiloxane comprising: (i) at least two siloxyl units and, preferably, at least three siloxyl units of the following formula: $\begin{array}{cc}{H}_d.Math.Z_c^3.Math.{\mathrm{SiO}}_{\frac{4.Math.\left(d+e\right)}{2}}& \left(B.Math.\mathrm{.1}\right)\end{array}$ in which: d=1 or 2, e=0, 1 or 2 and d+e=1, 2 or 3, the symbols Z.sup.3, which may be identical or different, represent a monovalent hydrocarbon group having from 1 to 30 carbon atoms and preferably chosen from the group consisting of alkyl groups having from 1 to 8 carbon atoms and aryl groups containing between 6 and 12 carbon atoms, and more preferably chosen from the group consisting of a methyl, ethyl, propyl, 3,3,3-trifluoropropyl, xylyl, tolyl and phenyl radical, and (ii) optionally at least one siloxyl unit of the following formula: $\begin{array}{cc}{Z}_c^2.Math.{\mathrm{SiO}}_{\frac{4-c}{2}}& \left(B.Math.\mathrm{.2}\right)\end{array}$ in which: c=0, 1, 2 or 3, the symbols Z.sup.2, which may be identical or different, represent a monovalent hydrocarbon group having from 1 to 30 carbon atoms and preferably chosen from the group consisting of alkyl groups having from 1 to 8 carbon atoms and aryl groups containing between 6 and 12 carbon atoms, and more preferably chosen from the group consisting of a methyl, ethyl, propyl, 3,3,3-trifluoropropyl, xylyl, tolyl and phenyl radical.

10. Crosslinked silicone material Y according to claim 1, wherein the composition X comprises a second organopolysiloxane compound comprising, per molecule, at least two C.sub.2-C.sub.6 alkenyl radicals bonded to silicon atoms, different from the organopolysiloxane compound A, said second organopolysiloxane compound being preferably divinyltetramethylsiloxane.

11. Crosslinked silicone material Y according to claim 1, wherein the proportions of the organopolysiloxane A and of the organohydrogenopolysiloxane B are such that the molar ratio of the hydrogen atoms bonded to the silicon in the organohydrogenopolysiloxane B to the alkenyl radicals bonded to the silicon in the organopolysiloxane A is between 0.2 and 20, preferably between 0.5 and 15, more preferably between 0.5 and 10 and even more preferably between 0.5 and 5.

12. Crosslinked silicone material Y according to claim 1, wherein, the composition X comprises one or several functional additives chosen from: silicone resins, adherence modulators, additives for increasing consistency, pigments, and heat-resistant, oil-resistant or fire-resistant additives, for example metal oxides.

13. Use of the catalyst C such as described according to claim 1 as silicone composition crosslinking catalyst.

14. Crosslinkable composition X comprising: at least one organopolysiloxane compound A comprising, per molecule, at least two C.sub.2-C.sub.6 alkenyl radicals bonded to silicon atoms, at least one organohydrogenopolysiloxane compound B comprising, per molecule, at least two hydrogen atoms bonded to an identical or different silicon atom, at least one catalyst C which is a complex corresponding to the following formula:
[Ni(L.sup.1).sub.2] in which: the symbol Ni represents nickel at degree of oxidation II; the symbols L.sup.1, which may be identical or different, represent a ligand which is a β-dicarbonylato anion or the enolate anion of a β-dicarbonylated compound, optionally at least one adhesion promoter D and optionally at least one charge E.

15. Method for crosslinking silicone compositions, comprising heating a composition X according to claim 14 to a temperature of between 70 and 200° C., preferably between 80 and 150° C., and more preferably between 80 and 130° C.

Description

EXAMPLE 1: NICKEL BASED CATALYSTS FOR THE CROSSLINKING OF DIVINYLTETRAMETHYLSILOXANE (DVTMS) WITH MD′.SUB.50.M

[0179] 1) Constituents

[0180] 1) Organopolysiloxane A: divinyltetramethylsiloxane (dvtms) (1.073 mole of vinyl radicals bonded to the silicon for 100 g of oil)

[0181] 2) Organohydrogenopolysiloxane B of formula: MD′.sub.50M (1.58 mole of hydrogen atoms bonded to the silicon for 100 g of oil), with: M: (CH.sub.3).sub.3SiO.sub.1/2; and D′: (CH.sub.3)HSiO.sub.2/2

[0182] 3) Catalysts (A), (B), (C), (D), (E) and (F):

##STR00010##

[0183] The catalysts (A), (B), (C) and (D) are available off the shelf, for example under the references Strem purity >95% for the compound [Ni(acac).sub.2], Strem purity >98% for the compound [Ni(TMHD).sub.2].

[0184] The catalyst (E) is obtained via a synthesis that is well known to those skilled in the art:

##STR00011##

[0185] The ketoester compound with R.sub.1=Methyl and R.sub.2=Methoxy (supplier: Sigma-Aldrich) is in a first step deprotonated using an equivalent of Bu-Li (supplier: Sigma-Aldrich) at low temperature (−78° C.). The salt obtained is re-crystallised in diethylether. The obtained deprotonated ligand (lithium salt) is added to a nickel chloride (NiCl.sub.2) in solution in the THF at ambient temperature (12 h). After decantation, filtration and concentration, the complex is re-crystallised in the THF.

[0186] The complex [Ni(ketoester).sub.2] has the form of a green apple solid.

[0187] The catalyst (F) is also obtained by synthesis well known to those skilled in the art:

##STR00012##

[0188] The diketone compound with R.sub.1=Phenyl and R.sub.2═C.sub.17H.sub.35 or C.sub.15H.sub.31 (supplier: Solvay) is in a first step deprotonated using an equivalent of Bu-Li (Supplier: Sigma-Aldrich) at low temperature (−78° C.). The salt obtained is re-crystallised in the diethylether. The obtained deprotonated ligand (lithium salt) is added to a nickel chloride (NiCl.sub.2) in solution in the THF at ambient temperature (12 h). The complex obtained is viscous, with a green coloration. A step of re-crystallisation makes it possible to lead to the obtaining of a solid.

[0189] II) Formulations and Results:

[0190] For each formulation tested, the catalyst is weighed and introduced into a Schlenk at ambient temperature and under inert atmosphere when the complex is sensitive to air (case in particular with Ni(0)), or into a glass flask when the complexes are stable in air.

[0191] 1.87 g of divinyltetramethylsiloxane (dvtms) then 1.27 g of oil MD′.sub.50M are then introduced. The flask (or Schlenk) is placed under stirring in an oil bath that will be heated to the desired reaction temperature.

[0192] The ratio R corresponds to the molar ratio of the hydrogen atoms bonded to the silicon (Si—H) in the organohydrogenopolysiloxane (MD′.sub.50M) to the alkenyl radicals (here vinyl) bonded to the silicon (Si—CH═CH.sub.2) in the organopolysiloxane (dvtms).

[0193] The start of crosslinking is measured. The start of crosslinking is defined as being the stopping of the stirring due to an increase in the viscosity of the medium.

TABLE-US-00001 TABLE 1 Reaction % mol of Start of Catalyst temperature catalyst.sup.(1) Ratio R Atmosphere crosslinking Formulation 1 Ni(COD).sub.2] 110° C. 0.25% 1:1 Inert   3 h 20 (comparative) (under argon) Formulation 2 [Ni(TMHD).sub.2] 110° C. 0.25% 1:1 Non-inert 1 h (invention) Formulation 3 Ni(II) 110° C. 0.25% 1:1 Non-inert 45 h  (comparative) stearate Formulation 4 [Ni(acac).sub.2] 110° C. 0.25% 1:1 Non-inert 2 h (invention) .sup.(1)Expressed as a molar % of nickel per number of moles of vinyl radicals bonded to the silicon (Si—CH═CH.sub.2) in dvtms

[0194] The comparative formulation 1 comprising a complex of Ni(0) crosslinks after 3h20 but must be maintained under inert atmosphere. Indeed, under a non-inert atmosphere, the complex breaks down very quickly, even before the start of the reaction, during the rise in temperature.

[0195] The formulations 2 and 4 according to the invention where the catalyst is a complex of Ni(II) having two β-dicarbonyl ligands crosslink in 1 to 2 h.

[0196] The comparative formulation 3, implementing a complex of Ni(II) having stearate ligands, crosslinks only after 45 h.

[0197] Furthermore the nickel catalysts according to the invention were tested in the following different operating conditions:

TABLE-US-00002 TABLE 2 Reaction % mol of Start of Catalyst temperature catalyst.sup.(1) Ratio R Atmosphere crosslinking Formulation 5 [Ni(TMHD).sub.2] 90° C.  0.25% 1:1 Non-inert Less than (invention) 15 h Formulation 6 [Ni(acac).sub.2] 90° C.  0.25% 1:1 Non-inert Less than (invention) 15 h Formulation 7 [Ni(TMHD).sub.2] 110° C.  0.125% 1:1 Non-inert Less than (invention) 15 h Formulation 8 [Ni(acac).sub.2] 110° C.  0.125% 1:1 Non-inert Less than (invention) 15 h Formulation 9 [Ni(ketoester).sub.2] 90° C.  0.25% 1:1 Non-inert 3.5 h (invention) Formulation 10 [Ni(ketoester).sub.2] 90° C. 0.125% 1:1 Non-inert Less than (invention) 15 h .sup.(1)Expressed as a molar % of nickel per number of moles of vinyl radicals bonded to the silicon (Si—CH═CH.sub.2) in dvtms

[0198] The formulations 5 and 6 according to the invention show that a crosslinking is obtained at 90° C., even if this crosslinking is slower than that observed for formulations 2 and 4 carried out at 110° C.

[0199] The formulations 7, 8 and 10 according to the invention show that a crosslinking is obtained at 0.125% molar of catalyst, even if this crosslinking is slower than that observed for formulations 2, 4 and 9 comprising 0.25% molar of catalyst.

EXAMPLE 2: NICKEL BASED CATALYSTS FOR THE CROSSLINKING OF M.SUP.VI .D.SUB.70 .M.SUP.VI .WITH MD′.SUB.50.M

I) Constituents

[0200] 1) Organopolysiloxane A of formula M.sup.viD.sub.70M (0.038 mole of vinyl radicals bonded to the silicon for 100 g of oil), with: Vi=Vinyl; M.sup.vi: (CH.sub.3).sub.2ViSiO.sub.1/2 and D: (CH.sub.3).sub.2SiO.sub.2/2

[0201] 2) Organohydrogenopolysiloxane B of formula: MD′.sub.50M (1.58 mole of hydrogen atoms bonded to the silicon for 100 g of oil), with: M: (CH.sub.3).sub.3SiO.sub.1/2; and D′: (CH.sub.3)HSiO.sub.2/2

[0202] 3) Catalysts (A), (B), (C), (D), (E) and (F) such as defined in example 1.

II) Formulations and results:

[0203] For each formulation tested, the catalyst is weighed and introduced into a Schlenk at ambient temperature and under inert atmosphere when the complex is sensitive to air (case with Ni(0)), or into a glass flask when the complexes are stable in air.

[0204] Oil M.sup.viD.sub.70M.sup.v1 then oil MD′.sub.50M were then introduced.

[0205] For a ratio R corresponding to the molar ratio of the hydrogen atoms bonded to the silicon (Si—H) in the organohydrogenopolysiloxane (MD′.sub.50M) to the alkenyl radicals (here vinyl) bonded to the silicon (Si—CH═CH.sub.2) in the organopolysiloxane (M.sup.viD.sub.70M.sup.vi) of 1:1, 4.39 g of oil M.sup.viD.sub.70M.sup.vi then 0.105 g of oil MD′.sub.50M were introduced.

[0206] The content in oil M.sup.viD.sub.70M.sup.vi and in oil MD′.sub.50M were adjusted according to the ratio R desired.

[0207] The flask (or Schlenk) is placed under stirring in an oil bath that will be heated to the desired reaction temperature.

[0208] The ratio R corresponds to the molar ratio of the hydrogen atoms bonded to the silicon (Si—H) in the organohydrogenopolysiloxane (MD′.sub.50M) to the alkenyl radicals (here vinyl) bonded to the silicon (Si—CH═CH2) in the organopolysiloxane (M.sup.viD.sub.70M.sup.vi).

[0209] The start of crosslinking is measured.

[0210] Study of the Duration of Crosslinking

TABLE-US-00003 TABLE 3 Reaction % mol of Start of Catalyst temperature catalyst.sup.(1) Ratio R Atmosphere crosslinking Formulation 11 [Ni(COD).sub.2] 110° C. 4% 1:1 Inert 2 h 50 (comparative) (under argon) Formulation 12 [Ni(TMHD).sub.2] 110° C. 4% 1:1 Non-inert 1 h 50 (invention) Formulation 13 Ni(II) 110° C. 4% 1:1 Non-inert No (comparative) stearate crosslinking at 48 h Formulation 14 [Ni(acac).sub.2] 110° C. 4% 1:1 Non-inert 2 h 20 (invention) .sup.(1)Expressed as a molar % of nickel per number of moles of vinyl radicals bonded to the silicon (Si—CH═CH.sub.2) in the organopolysiloxane (M.sup.viD.sub.70M.sup.vi)

[0211] The formulation 11 comprising a complex of Ni(0) crosslinks after 2h50 but must be maintained under inert atmosphere. Indeed, as already indicated in example 1, the complex breaks down very quickly under a non-inert atmosphere, even before the start of the reaction.

[0212] The formulations 12 and 14 according to the invention where the catalyst is a complex of Ni(II) having two β-dicarbonyl ligands crosslink after about 1h50 to 2h20.

[0213] The comparative formulation 13, implementing a complex of Ni(II) having stearate ligands, still does not crosslink after 48 h.

[0214] Furthermore the catalysts (E) and (F) according to the invention were tested in the following different operating conditions:

TABLE-US-00004 TABLE 4 Reaction % mol of Ratio Start of Catalyst temperature catalyst.sup.(1) R crosslinking Formulation [Ni(ketoester).sub.2] 110° C.   2%   1:1  5 h 15 (invention) Formulation [Ni(ketoester).sub.2] 110° C. 1.6% 1.6:1 30 min 16 (invention) Formulation [Ni(Rhodiastab).sub.2] 110° C. 0.8% 1.6:1  3 h 17 (invention) .sup.(1)Expressed as a molar % of nickel per number of moles of vinyl radicals bonded to the silicon (Si—CH═CH.sub.2) in the organopolysiloxane (M.sup.viD.sub.70M.sup.vi)

[0215] Study of the Effect of the Temperature

TABLE-US-00005 TABLE 5 Effect of the increase in temperature (1) Reaction % mol of Start of Catalyst temperature catalyst.sup.(1) Ratio R Atmosphere crosslinking Formulation 18 [Ni(TMHD).sub.2]  90° C. 2% 1:1 Non-inert 17 h (invention) Formulation 19 [Ni(TMHD).sub.2] 110° C. 2% 1:1 Non-inert 2 h 20 (invention) Formulation 20 [Ni(TMHD).sub.2] 130° C. 2% 1:1 Non-inert 10 min (invention) .sup.(1)Expressed as a molar % of nickel per number of moles of vinyl radicals bonded to the silicon (Si—CH═CH.sub.2) in the organopolysiloxane (M.sup.viD.sub.70M.sup.vi)

TABLE-US-00006 TABLE 6 Effect of the increase in temperature (2) Reaction % mol of Start of Catalyst temperature catalyst.sup.(1) Ratio R Atmosphere crosslinking Formulation 21 [Ni(acac).sub.2]  90° C. 1.6% 3.1:1 Non-inert 3 h (invention) Formulation 22 [Ni(acac).sub.2] 110° C. 1.6% 3.1:1 Non-inert 20 min (invention) Formulation 23 [Ni(acac).sub.2] 130° C. 1.6% 3.1:1 Non-inert 8 min (invention) .sup.(1)Expressed as a molar % of nickel per number of moles of vinyl radicals bonded to the silicon (Si—CH═CH.sub.2) in the organopolysiloxane (M.sup.viD.sub.70M.sup.vi)

[0216] The formulations 18 to 23 according to the invention show that the increase in temperature makes it possible to significantly reduce crosslinking time.

[0217] Study of the Effect of the Concentration in Catalyst

TABLE-US-00007 TABLE 7 effect of the increase in the concentration of catalyst (1) Reaction % mol of Start of Catalyst temperature catalyst.sup.(1) Ratio R Atmosphere crosslinking Formulation 24 [Ni(TMHD).sub.2] 110° C. 1% 1:1 Non-inert 26 h    (invention) Formulation 19 [Ni(acac).sub.2] 110° C. 2% 1:1 Non-inert 2 h 20 (invention) Formulation 12 [Ni(acac).sub.2] 110° C. 4% 1:1 Non-inert 1 h 50 (invention) .sup.(1)Expressed as a molar % of nickel per number of moles of vinyl radicals bonded to the silicon (Si—CH═CH.sub.2) in the organopolysiloxane (M.sup.viD.sub.70M.sup.vi)

TABLE-US-00008 TABLE 8 effect of the increase in the concentration of catalyst (2) Reaction % mol of Start of Catalyst temperature catalyst.sup.(1) Ratio R Atmosphere crosslinking Formulation 25 [Ni(TMHD).sub.2] 110° C. 0.16%  3.1:1 Non-inert 5 h (invention) Formulation 26 [Ni(acac).sub.2] 110° C. 0.4% 3.1:1 Non-inert 1 h 30 (invention) Formulation 27 [Ni(acac).sub.2] 110° C. 0.8% 3.1:1 Non-inert 1 h 20 (invention) Formulation 28 [Ni(acac).sub.2] 110° C. 1.6% 3.1:1 Non-inert 20 min (invention) Formulation 29 [Ni(acac).sub.2] 110° C. 3.1% 3.1:1 Non-inert 20 min (invention) .sup.(1)Expressed as a molar % of nickel per number of moles of vinyl radicals bonded to the silicon (Si—CH═CH.sub.2) in the organopolysiloxane (M.sup.viD.sub.70M.sup.vi)

[0218] The formulations 12, 19 and 24 to 29 according to the invention show that the increase in the concentration of catalyst makes it possible to significantly reduce crosslinking time. The formulation 25 further shows that the crosslinking can be observed even with very low catalyst contents, which makes it possible to prevent or limit the coloration of the crosslinked material.

[0219] Study of the Effect of the Ratio R

TABLE-US-00009 TABLE 9 Effect of the ratio R(1) Reaction % mol of Ratio Start of Catalyst temperature catalyst.sup.(1) R crosslinking Formulation 14 [Ni(acac).sub.2] 110° C. 4% 1:1 2 h 20 (invention) Formulation [Ni(acac).sub.2] 110° C. 4% 2:1 1 h 50 14a (invention) .sup.(1)Expressed as a molar % of nickel per number of moles of vinyl radicals bonded to the silicon (Si—CH═CH.sub.2) in the organopolysiloxane (M.sup.viD.sub.70M.sup.vi)

TABLE-US-00010 TABLE 10 Effect of the ratio R (2) Reaction % mol of Ratio Start of Catalyst temperature catalyst.sup.(1) R crosslinking Formulation 30 [Ni(acac).sub.2] 110° C. 1.6% 0.8:1  3 h (invention) Formulation 31 [Ni(acac).sub.2] 110° C. 1.6% 3.1:1 20 min (invention) .sup.(1)Expressed as a molar % of nickel per number of moles of vinyl radicals bonded to the silicon (Si—CH═CH.sub.2) in the organopolysiloxane (M.sup.viD.sub.70M.sup.vi)

[0220] The crosslinkings are carried out under a non-inert atmosphere. The formulations 14 and 14A, and 30 and 31 show that the increase in the ratio R makes it possible to reduce crosslinking time.

[0221] Duration of Crosslinking of Catalysts (A), (B), (E) and (F)

[0222] Finally, the crosslinking for the catalysts (A), (B), (E) and (F) was tested with a ratio R of 1.6:1. The results are presented in table 8.

TABLE-US-00011 TABLE 8 Reaction % mol of Ratio Start of Catalyst temperature catalyst.sup.(1) R crosslinking Formulation [Ni(acac).sub.2] 110° C. 1.6% 1.6:1 25-30 min 32 (invention) Formulation [Ni(TMHD).sub.2] 110° C. 1.6% 1.6:1 25-30 min 33 (invention) Formulation [Ni(cetoester).sub.2] 110° C. 1.6% 1.6:1 30 min 34 (invention) Formulation [Ni(Rhodiastab).sub.2] 110° C. 1.6% 1.6:1 2 h 30-3 h 35 (invention) .sup.(1)Expressed as a molar % of nickel per number of moles of vinyl radicals bonded to the silicon (Si—CH═CH.sub.2) in the organopolysiloxane (M.sup.viD.sub.70M.sup.vi)

[0223] The crosslinkings are carried out under a non-inert atmosphere. The formulations 32 to 35 show that the crosslinking is observed for different nickel based catalysts at the degree of oxidation (II).

EXAMPLE 3: CATALYST [NI(TMHD).SUB.2.] FOR THE CROSSLINKING OF M.SUP.VI .D.SUB.350 .M.SUP.VI .WITH MD′.SUB.50.M

I) Constituents

[0224] 1) Organopolysiloxane A of formula M.sup.viD.sub.350M.sup.vi, with: Vi=Vinyl; M.sup.vi: (CH.sub.3).sub.2ViSiO.sub.1/2 and D: (CH.sub.3).sub.2SiO.sub.2/2

[0225] 2) Organohydrogenopolysiloxane B of formula: MD′.sub.50M (1.58 mole of hydrogen atoms bonded to the silicon for 100 g of oil), with: M: (CH.sub.3).sub.3SiO.sub.1/2; and D′: (CH.sub.3)HSiO.sub.2/2

[0226] 3) Catalyst (A) such as defined in the example 1.

II) Formulations and Results:

[0227] We weighed 12.4 g of M.sup.viD.sub.350M.sup.vi with: Vi=Vinyl; M.sup.vi: (CH.sub.3).sub.2ViSiO.sub.1/2 and D: (CH.sub.3).sub.2SiO.sub.2/2 and 0.6 g of MD′.sub.50M (1.58 mole of hydrogen atoms bonded to the silicon for 100 g of oil), with:

[0228] M: (CH.sub.3).sub.3SiO.sub.1/2; and D′: (CH.sub.3)HSiO.sub.2/2

[0229] The ratio R corresponding to the molar ratio of the hydrogen atoms bonded to the silicon (Si—H) in the organohydrogenopolysiloxane (MD′.sub.50M) on the alkenyl radicals (here vinyl) bonded to the silicon (Si—CH═CH.sub.2) in the organopolysiloxane (M.sup.viD.sub.350M.sup.vi) of 10:1.

[0230] 5 mol % of catalyst [Ni(TMHD)2] (expressed as a molar % of nickel per number of moles of vinyl radicals bonded to the silicon (Si—CH═CH.sub.2) in the organopolysiloxane (M.sup.viD.sub.350M.sup.vi)) is dissolved at ambient temperature in the oil MD′.sub.50M and the mixture is incorporated at ambient temperature in the oil M.sup.viD.sub.350M.sup.vi. The whole is placed in a Teflon mould then into an oven at 110° C.

[0231] After two hours, the crosslinked material is demoulded and its hardness (in Shore A) measured. The material has a hardness of 9 in Shore A degrees.

[0232] This example makes it possible to show that the implementing of catalysts claimed in crosslinking reactions of organopolysiloxane compound A with an organohydrogenopolysiloxane compound B allows for the obtaining of materials Y of which the hardness can be measured.