NOVEL SILICONE COMPOSITION CROSSLINKING CATALYSTS
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 2 -C 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 1 ) 2 ] where Ni represents nickel at degree of oxidation II; L 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.
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 2 -C 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 1 ) 2 ]
in which:
the symbol Ni represents nickel at degree of oxidation II,
the symbols L 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 2 -C 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 1 is an anion derived from a compound of formula (1):
R 1 COCHR 2 COR 3 (1)
in which:
R 1 and R 3 , which may be identical or different, represent a C 1 -C 30 linear, cyclic or branched hydrocarbon radical, an aryl containing between 6 and 12 carbon atoms, or a —OR 4 radical with R 4 which represents a C 1 -C 30 linear, cyclic or branched hydrocarbon radical,
R 2 is a hydrogen atom or a hydrocarbon radical, preferably alkyl, comprising from 1 to 4 carbon atoms; with
R 1 and R 2 can be connected in order to form a C 5 -C 6 cycle, and
R 2 and R 4 can be connected in order to form a C 5 -C 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) 2 ], [Ni(TMHD) 2 ], [Ni(ketoester) 2 ] and [Ni(Rhodiastab 50) 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:
W
a
Z
b
SiO
d
-
(
a
+
b
)
2
(
A
.1
)
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 2 -C 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:
Z
a
1
SiO
4
-
a
2
(
A
.2
)
in which:
a=0, 1, 2 or 3,
the symbols Z 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:
H
d
Z
c
3
SiO
4
(
d
+
e
)
2
(
B
.1
)
in which:
d=1 or 2, e=0, 1 or 2 and d+e=1, 2 or 3,
the symbols Z 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:
Z
c
2
SiO
4
-
c
2
(
B
.2
)
in which:
c=0, 1, 2 or 3,
the symbols Z 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 2 -C 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 2 -C 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 1 ) 2 ]
in which:
the symbol Ni represents nickel at degree of oxidation II;
the symbols L 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.