Wacker-chemie Gmbh

Jorg Patzke

Karl-Heinrich Wegehaupt

Dietrich Wolfer

Carlos Weise

Karl Braunsperger

Jurgen Burkhardt

Herbert Krohberger

A process for preparing diorganopolysiloxanes containing terminal triorganosiloxy groups which comprises reacting in a 1st step, a cyclic diorganopolysiloxane and/or diorganodichlorosilane hydrolyzate with from 0.05 to 3 percent by weight of triorganochlorosilane, based on the weight of the cyclic diorganopolysiloxane and/or diorganodichlorosilane hydrolyzate employed in the presence of from 1 to 50 ppm by weight of phosphonitrile chloride, based on the total weight of the organosilicon compounds employed, to form a reaction mixture containing .alpha.-triorganosiloxy-.omega.-chlorodiorganopolysiloxane, and in a 2nd step, adding to the reaction mixture obtained in the 1st step and containing the .alpha.-triorganosiloxy-.omega.-chlorodiorganopolysiloxane, a diorganopolysiloxane having one Si-bonded hydroxyl group in each of the terminal units in an amount of from 1 to 1.2 gram-moles of Si-bonded hydroxyl group in this diorganopolysiloxane per gram-atom of Si-bonded chlorine in the triorganochlorosilane, and in a 3rd step, adding hexaorganodisilazane to the reaction mixture of the 2nd step in order to deactivate the phosphonitrile chloride and remove hydrogen chloride from the diorganopolysiloxanes containing terminal triorganosiloxy groups and thereafter removing the low-boiling components by distillation.

Process for preparing diorganopolysiloxanes having terminal

Flame-resistant molding compositions are prepared by adding at least one substance selected from the class consisting of (a) oxides or hydroxides of the rare earth metals, (b) graphite, or (c) precious metals or their compounds or complexes and mixtures of (a), (b) or (c) to a composition containing mixtures of organic polymers other than diorganopolysiloxanes and diorganopolysiloxanes. Although it is not essential, silicon dioxide having a surface area of at least 50 m.sup.2 /g and crosslinking agents may be incorporated in these molding compositions.

Flame-resistant molding compositions containing oxides or hydroxides of

Flame-resistant molding compositions

Elastomers which are obtained by crosslinking an organopolysiloxane composition containing a diorganopolysiloxane, an organic peroxide and calcium hydroxide which has been treated with an organosilicon compound to impart hydrophobic properties thereto.

Organopolysiloxane elastomers

Highly transparent or optically clear elastomers are prepared by mixing (1) a nitrogen containing compound having at least one triorganosilyl group in which at least one nitrogen atom is linked either directly to a silicon atom or via an oxygen atom, but no more than one triorganosilyl group is linked to a nitrogen atom and no more than one condensable group is linked to a silicon atom, (2) a hexaorganodisilazane, (3) silicon dioxide having a surface area of at least 50 m.sup.2 /g with (4) a highly viscous diorganopolysiloxane. The resulting composition may be cured by the addition of a curing agent to form highly transparent or optically clear elastomers.

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Burghausen, Germany

Jorg Patzke