Wacker Chemie Ag

Georg Loessel

Manfred Meisenberger

Frank Sandmeyer

Marko Prasse

Volker Stanjek

Daniel Schildbach

Enno Funk

Gerhard Staiger

Wolfgang Wewers

Steffen Doerrich

Frank Betschinger

Pedro Marani

Alkylsilicone resins containing at least 20 mol percent of siloxy units bearing a >Calkyl group and having from 5-20 weight percent of alkoxy groups may be prepared directly by hydrolysis of chlorosilanes, and are highly effective as bulk hydrophobing agents in the preparation of fibrocement.

Alkyl silicone resin as additive for hyrophobising fibre cement

High hydroxyl-content organopolysiloxanes of low molecular weight are prepared in a continuous process by metering in alkoxysilanes and chlorosilanes in a weight proportion of 60:40 or more to a reaction mixture containing water and non-polar solvent, and continuously removing an organic phase containing organopolysiloxanes from the reaction mixture.

Method for producing SiOH-functional polysiloxanes

Organopolysiloxanes having an OH content of 3.0-10.0% by weight are produced in a continuous process in which silanes of the formula IRSiRX&#x2003;&#x2003;(I),in which with the proviso that 4&#x2212;m=n+o, and that in at least 30 mol % of the silanes of the general formula I, n&#x2260;0 und o&#x2260;0, water, and water-insoluble non-polar solvent are metered in continuously into a reactor to form a reaction mixture and the reaction mixture is continuously discharged from the reactor.

Multistep continuous and semicontinuous hydrolysis and condensation of chlorosilanes with alcohol containing minimal water in a column in a first step to form a silicone resin intermediate, followed by further condensation provides silicone resins in reproducible fashion substantially free of hydrogen chloride, without reactor gelatin.

Process for preparing organopolysiloxanes

Organopolysiloxanes having an OH content of from 3.0-10.0 weight percent are continuously produced by continuously feeding chlorosilanes, alkoxysilanes, water, and nonpolar solvent essentially non-miscible in water, continuously discharging a reaction mixture containing organopolysiloxanes dissolved in a solvent phase, and optionally separating organopolysiloxanes from the solvent phase, wherein the chlorosilanes and alkoxysilanes are added in respective weight fractions of 95-60% and 5-40% based on the total weight of chlorosilanes and alkoxysilanes. The process does not employ and polar solvents, and produces products with improved flash points while minimizing complexity and expense of waste water treatment.

Highly condensed silicon resins are obtained by a three step continuous procedure without the use of organic solvent, by preliminarily forming a partial alkoxylate by reacting a chlorosilane with alcohol containing no or a minimal amount of water, feeding the partial alkoxylate to a reaction column to form a silicone resin of low degree of condensation, and further condensing the silicone resin intermediate thus formed to produce a silicone resin product.

Method for producing organopolysiloxanes

Addition-crosslinkable silicone resin compositions containing a branched organopolysiloxane bearing each of Si&#x2014;H groups, alkenyl groups, and aryl groups, and also containing blocks of linear organopolysiloxane free of Si&#x2014;H and alkenyl groups with a chain length of at least three siloxy groups, and further bearing at least one aryl group, serve as excellent potting compositions for electronic devices, particularly LEDs, with high refractive index and optical transmittance, and wide processing latitude.

Silicone resin composition for optical semiconductors

Silsesquisiloxanes are produced in high yield and purity in a minimal number of process steps by reacting quaternary ammonium silicates with disiloxanes in a precipitant liquid which causes the silsesquisiloxane product to be precipitated in high purity.

Method for producing organo-oligo silsesquioxanes

One-component, H-siloxane-containing addition-crosslinkable silicone resins, are prepared by charging a reactor with water and a solvent mixture of at least one aromatic solvent and at least one alkyl ester, adding a chlorosilane mixture containing an Si&#x2014;H functional silane and a silane bearing an unsaturated hydrosilylatable group with stirring, the temperature not being above 50&#xb0; C., separating an aqueous phase comprising a one-component, H-siloxane-containing addition-crosslinkable silicone resin, and washing the phase comprising the one-component, H-siloxane-containing addition-crosslinkable silicone resin in at least two washing steps to reduce residual HCl content, a final washing carried out using a 0.01%-1.0% strength aqueous solution of a base with a pH between 7.00-8.50, at a temperature of 20-50&#xb0; C.

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Emmerting, Germany

Georg Loessel