Patent ID: 7504468
Filing Date: 2009-03-17
Classification: C08G,C08K,C08L

Abstract:
1. A single-component polyorganosiloxane composition (POS) which is stable on storage in the absence of moisture and which crosslinks in the presence of water to give a non-yellowing and adherent elastomer, said composition comprising: (i) at least one crosslinkable linear polyorganopolysiloxane A of formula: in which: the substituents R the substituents R the functionalization substituents R an iminoxy residue of formula: wherein R 3 independently is a linear or branched C 1 to C 8 alkyl radical, a C 3 to C 8 cycloalkyl radical or a C 2 -C 8 alkenyl radical; an alkoxy residue of formula: wherein R 4 independently is a linear or branched C 1 to C 8 alkyl radical or a C 3 to C 8 cycloalkyl radical and b=0 or 1; an acyloxy residue of formula: R an epoxy residue of formula: wherein R 5 is as defined above and b′=0, 1 or 2; each symbol Y represents an oxygen atom or a divalent hydrocarbon radical; n has a value sufficient to confer, on the POS A, a dynamic viscosity at 25° C. ranging from 1,000 to 1,000,000 mPa·s; a is zero or 1; (2i) optionally, at least one polyorganosiloxane resin B functionalized by at least one radical R (3i) optionally, at least one crosslinking agent C of formula: wherein R 2 , R fo and a are as defined above; (4i) optionally, a residual amount of the functionalization catalyst D in the presence of which the preparation of the POS(s) A and of the optional resin(s) B which are functionalized by R (5i) optionally, at least one primary aliphatic C (6i) optionally, at least one unreactive linear polydiorganosiloxane F which is not functionalized by R in which: the substituents R m has a value sufficient to confer, on the polymer of formula (III), a dynamic viscosity at 25° C. ranging from 10 to 200,000 mPa·s; (7i) at least one inorganic filler G; (8i) optionally, at least one auxiliary agent H; (9i) an effective amount of a crosslinking/curing catalyst I; said composition further comprising the following parameters (α), (β) and (γ): (α) the curing catalyst I comprises the combination of at least one organic derivative I1 of a metal M1 selected from among titanium, zirconium and mixtures thereof with at least one organic derivative 12 of a metal M2 selected from among zinc, aluminum, boron, bismuth and mixtures thereof; wherein the amount of curing catalyst I is such that: (β) the number of μg.at (microgram atoms) of the metals M1+M2 introduced into 1 g of single-component composition comprising all the ingredients (i) to (8i) is within the range from 25 to 55; (γ) the ratio: is within the range from 10 to 45%.