Patent ID: 6777471
Filing Date: 2004-08-17
Classification: C08G,C08L

Abstract:
Single-component organopolysiloxane compositions which are stable on storage in the absence of moisture and which crosslink to translucent and adherent elastomers in the presence of moisture, made in a single closed reactor with stirring, by the process, batchwise or continuous, comprising the successive following steps 1 to 3:step 1: functionalization by reacting a mixture of at least one reactive linear diorganopolysiloxane A comprising a hydroxyl group at each chain end, of formula (I) defined below, at least one hydroxylated organopolysiloxane resin B, as defined below, presenting in its structure at least two different units, at least one polyalkoxysilane C as defined below, optionally, at least one aliphatic C1 to C3 alcohol E, and, optionally, at least one nonreactive linear diorganopolysiloxane F as defined below, said functionalization being carried out in the presence of a catalytically effective amount of a functionalization catalyst D, provided that said catalyst is not an organic titanium derivative, step 2: blending or compounding by adding in any order into the reacted mixture obtained in step 1, which is kept stirred, an inorganic filler G comprising an amorphous silica in the form of a solid, an effective amount of a curing catalyst H as defined below, comprising at least one organic titanium derivative, optionally, at least one nonreactive linear diorganopolysiloxane F as defined below, and optionally, at least one auxiliary agent I, and step 3: subjecting the blended or compounded mixture obtained in step 2, which is kept stirred, to a devolatilization operation carried out under a pressure below atmospheric pressure, wherein the reactive linear diorganopolysiloxane A is of formula (I): wherein: R1 substituents, which are identical or different, represent an aliphatic, cyclic or aromatic, saturated or unsaturated, substituted or unsubstituted, C1 to C13 monovalent hydrocarbonaceous group, n has a value sufficient to confer, on the diorganopolysiloxanes of formula (I), a dynamic viscosity at 25Â° C. from 1 000 to 1 000 000 mPaÂ·s, the hydroxylated organopolysiloxane resin B exhibits in its structure, at least two different units selected from the group consisting of the units of formulae (R1)3SiO1/2 (M unit), (R1)2SiO2/2(D unit), R1SiO3/2(T unit) and SiO2 (Q unit), at least one of these units being a T or Q unit, said R1 groups, which are identical or different, being as defined above in formula (I), said resin containing hydroxyl groups and having a content by weight of hydroxyl group ranging from 0.1 to 10%, the polyalkoxysilane C is of formula (II): (R2)aSi[(OCH2CH2)bOR3]4âˆ’aâ€ƒâ€ƒ(II) wherein: R2 represents an aliphatic, cyclic or aromatic, saturated or unsaturated, substituted or unsubstituted, C1 to C13 monovalent hydrocarbonaceous group R3, which is identical or different, represents a linear or branched C1 to C8 alkyl group, a is zero or 1, b is zero or 1; the nonreactive linear diorganopolysiloxane F is of formula (III): wherein: R1, which is identical or different, is as defined above in formula I, m has a value sufficient to confer, on the polymers of formula (III), a dynamic viscosity at 25Â° C. from 10 to 200 000 mPaÂ·s; the catalyst H is selected from the group consisting of H1 monomers and H2 polymers, H1 monomers being of formula (IV) Ti[(OCH2CH2)cOR4]4â€ƒâ€ƒ(IV) wherein: R4 , which is identical or different, represents a linear or branched C1 to C12 alkyl group, c is zero, 1 or 2, provided that when the c symbol represents zero, R4 has from 2 to 12 carbon atoms and, when the c symbol represents 1 or 2, R4 has from 1 to 4 carbon atoms, H2 polymers resulting from the partial hydrolysis of monomers of formula (IV) in which the R4 symbol has the above mentioned meaning with the c symbol represent zero.