Dow Corning Corporation

Stephanie Lobry

Frederic Gubbels

Victor Baily

Amedee Ratsimihety

A curable phenylorganosiloxane polymer composition comprising: (a) 100 parts by weight of a phenylorganosiloxane having a viscosity of at least 10000 mPa&#xb7;s at 25&#xb0; C. and at least two reactive groups per molecule selected from (i) &#x2014;OH or hydrolysable groups and (ii) unsaturated groups; (c) 0 to 500 parts by weight of fillers per 100 parts by weight of (a); (d) a suitable cure package comprising a cross-linker and a catalyst the suitable cure package being selected from a silane or polyorganosiloxane and a condensation catalyst when (a) is (a) (i) or a hydrosilylation catalyst when (a) is (a) (ii); and (b) 0.1 to 300 parts by weight of at least one phenyl siloxane resin per 100 parts by weight of (a). The compositions are especially useful in sealants (particularly in sealants for insulating glass units (IGUs), due to their low gas permeability), in conformal coatings and for corrosion protection.

Organosiloxane compositions

The present invention relates to a process for the production of an intermediate siloxane monomer and use of said monomer to produce high molecular weight linear polysilalkylenesiloxanes. The siloxane monomer is prepared by ring opening polymerization of a cyclic monomer of the structure in the presence of an acidic or basic ring opening polymerization catalyst; to form a mixture of siloxane monomers and linear oligomers. The linear oligomers are then extracted and discarded before a further step of ring opening polymerization using the aforementioned intermediate siloxane monomer mixture as the starting material. The second polymerization step is undertaken at a temperature within the melting point range of said siloxane monomer mixture. The intermediate, final product and methods of their manufacture are described. 

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Romb. Marchipont, France

Stephanie Lobry