Silicone composition crosslinking catalysts
The invention relates to a crosslinkable composition X, comprising: at least one organopolysiloxane compound A comprising, per molecule, at least two C2-C6 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: [Fe(L1)2] in which: the symbol Fe represents iron at degree of oxidation II; the symbols L1, 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. The invention also relates to the use of the previously described catalyst C as silicone composition crosslinking catalyst, to a silicone composition crosslinking method, wherein it comprises heating the composition X to a temperature of between 70 and 200° C., and to the resulting crosslinked silicone material Y.
1. A crosslinkable composition X comprising:
at least one organopolysiloxane compound A comprising, per molecule, at least two C2-C6 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:
[Fe(L 1 ) 2 ]
in which:
the symbol Fe represents iron in oxidation state 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-dicarbonyl compound,
optionally at least one adhesion promoter D and
optionally at least one filler E,
wherein said composition is free of any catalysts comprising rhodium.
2. The composition X as claimed in claim 1 , wherein the catalyst C is present in a content ranging from 0.001 to 10 mol % of iron per number of moles of C 2 -C 6 alkenyl radicals bonded to silicon atoms in the organopolysiloxane compound A.
3. The composition X claimed in claim 1 , wherein said composition is free of catalyst based on any of platinum, palladium, ruthenium or rhodium.
4. The composition X as claimed in 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 linear, cyclic or branched C 1 -C 30 hydrocarbon-based radical, an aryl containing between 6 and 12 carbon atoms or a radical
OR 4 with R 4 representing a linear, cyclic or branched C 1 -C 30 hydrocarbon-based radical,
R 2 is a hydrogen atom or a hydrocarbon-based radical; wherein
R 1 and R 2 may be joined together to form a C 5 -C 6 ring, and
R 2 and R 4 may be joined together to form a C 5 -C 6 ring.
5. The composition X as claimed in claim 4 , in which the compound of formula (1) is chosen from the group formed by the following β-diketones: 2,4-pentanedione (acac); 2,4-hexanedione; 2,4-heptanedione; 3,5-heptanedione; 3-ethyl-2,4-pentanedione; 5-methyl-2,4-hexanedione; 2,4-octanedione; 3,5-octanedione; 5,5-dimethyl-2,4-hexanedione; 6-methyl-2,4-heptanedione; 2,2-dimethyl-3,5-nonanedione; 2,6-dimethyl-3,5-heptanedione; 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; dibenzoylmethane; 3-methyl-2,4-pentadione; 3-acetyl-2-pentanone; 3-acetyl-2-hexanone; 3-acetyl-2-heptanone; 3-acetyl-5-methyl-2-hexanone; benzoylstearoylmethane; benzoylpalmitoylmethane; octanoylbenzoylmethane; 4-t-butyl-4′-methoxydibenzoylmethane; 4,4′-dimethoxydibenzoylmethane and 4,4′-di-tert-butyldibenzoylmethane.
6. The composition X as claimed in claim 4 , in which the compound of formula (1) is chosen from the group formed from the β-diketones 2,4-pentanedione (acac) or 2,2,6,6-tetramethyl-3,5-heptanedione (TMHD).
7. The composition X as claimed in claim 1 , in which the catalyst C is chosen from the complexes [Fe(acac) 2 ] and [Fe(TMIHD) 2 ].
8. The composition X as claimed in claim 1 , wherein the organopolysiloxane A comprises:
(i) at least two siloxyl units (A.1), which may be identical or different, having the following formula:
W
a
Z
b
SiO
4
-
(
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 linear or branched C 2 -C 6 alkenyl group,
and the symbols Z, which may be identical or different, represent a monovalent hydrocarbon-based group containing from 1 to 30 carbon atoms,
(ii) and optionally at least one siloxyl unit having the following formula:
Z
a
1
SiO
4
-
a
2
(
A
.2
)
in which:
a=0, 1, 2 or 3,
the symbols Z′, which may be identical or different, represent a monovalent hydrocarbon-based group containing from 1 to 30 carbon atoms.
9. The composition X as claimed in claim 1 , in which the organohydrogenopolysiloxane compound B comprises at least three hydrogen atoms per molecule directly bonded to an identical or different silicon atom.
10. The composition X as claimed in claim 1 , in which the organohydrogenopolysiloxane compound B is an organopolysiloxane comprising:
(i) at least two siloxyl units having the following formula:
H
d
Z
e
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-based group containing from 1 to 30 carbon atoms and
(ii) optionally at least one siloxyl unit having 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-based group containing from 1 to 30 carbon atoms.
11. The composition X as claimed in claim 1 , wherein said composition 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 I .
12. The composition X as claimed in claim 1 , wherein proportions of the organopolysiloxane A and of the organohydrogenopolysiloxane B are such that the mole ratio of hydrogen atoms bonded to silicon in the organohydrogenopolysiloxane B to the alkenyl radicals bonded to silicon in the organopolysiloxane A is between 0.2 and 20.
13. The composition X as claimed in claim 1 , wherein said composition comprises one or more functional additives chosen from:
silicone resins,
adhesion modifiers,
consistency-enhancing additives,
pigments, and
heat-resistance, oil-resistance or fire-resistance additives, optionally metal oxides.
14. A process for crosslinking one or more silicone compositions, wherein said process comprises heating a composition X as claimed in claim 1 to a temperature ranging from 70 to 200° C.
15. A crosslinked silicone material Y obtained by heating to a temperature ranging from 70 to 200° C., a composition X as claimed in claim 1 .
16. The composition X as claimed in claim 1 , wherein said composition comprises a second organopolysiloxane compound which is a divinyltetramethyl disiloxane.
17. A silicone composition product crosslinked with a catalyst C, which is a complex corresponding to the following formula:
[Fe(L 1 ) 2 ]
in which:
the symbol Fe represents iron in oxidation state 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-dicarbonyl compound, wherein said composition is not crosslinked with any catalysts comprising rhodium.