摘要:
A process for preparing organosiloxane block copolymers which comprises reacting (a) an organopolysiloxane containing Si-bonded hydroxyl groups and having an average molecular weight of at least 800 g/mole, in which at least 80 mole percent of the units are siloxane units, and one valence of each silicon atom is satisfied by an SiC-bonded organic radical, while the remaining silicon valences are satisfied by siloxane oxygen atoms or hydroxyl groups, with (b) a diorganopolysiloxane having one Si-bonded hydroxyl group in each terminal unit and an average of at least 10 silicon atoms per molecule in the presence of (c) an organic solvent and (d) an alkali metal carbonate and/or an alkali metal carboxylate to form an organosiloxane block copolymer.
摘要:
A process for preparing organopolysiloxanes having SiC-bonded organofunctional groups, which comprises reacting an organopolysiloxane containing SiC-bonded hydroxyl and/or alkoxy groups and having an average of about 0.85 to 1.8 SiC-bonded monovalent hydrocarbon radicals or halogenated monovalent hydrocarbon radicals for each Si atom, with an organosilicon compound containing alkoxy groups and/or siloxane oxygen groups and at least one SiC-bonded organofunctional radical per molecule in the presence of an organic solvent and a basic catalyst.The resultant organopolysiloxanes having SiC-bonded organofunctional groups may, for example, be used for preparing modified polymers by copolymerizing the organopolysiloxanes with a monomer containing an aliphatic double bond, such as styrene or hydroxyethyl methacrylate, or by reacting the organopolysiloxanes with an additional polymer such as an epoxy resin. When a monomer, containing an aliphatic double bond is used in the copolymerization, the resultant modified polymers may be used to manufacture hard contact lenses.
摘要:
Silicone resin powders are obtained by spray drying aqueous colloidal suspensions of organopolysiloxanes which are prepared by adding an alkoxysilane and/or a partial hydrolysate thereof and, if appropriate, mixed with an organo(poly)siloxane which is free of alkoxy groups and contains a maximum of 8 siloxane units per molecule, to water in the presence of an emulsifier at a maximum rate of 5 moles of organosilicon compound per hour per liter of water.
摘要:
Colloidal suspensions of organopolysiloxanes are prepared by mixing an organosilicon compound selected from the group consisting of mixtures of alkoxysilanes and/or partial hydrolysates thereof and an organo(poly)siloxane which is optionally free of alkoxy groups and contains a maximum of 8 siloxane units, which is mixed with at least one alkoxysilane and/or a partial hydrolysate thereof, with water in the presence of an emulsifier, at a maximum rate of 5 moles of organosilicon compound per hour per liter of water, in which the organosilicon compound and the water is fed continuously, but separately from one another, into a reactor, in which at least one of the two substances contains an emulsifier, while the alkanol is being continuously removed by distillation from the aqueous suspension continuously emerging from the reactor. The aqueous suspension from which the alkanol has been removed by distillation is, if desired, recycled back into the reactor. A tubular reactor is preferably employed in which the water is added continuously at, or near the upper end of the tubular reactor and the organosilicon compound is added via several inlet points arranged along the longitudinal axis of the tubular reactor.
摘要:
Organopolysiloxane modified organic polymers are prepared by reacting organic polymers containing C-bonded hydroxyl groups with organopolysiloxanes containing Si-bonded hydroxyl groups and/or alkyl groups which are bonded to silicon via oxygen in the presence of water in excess of any formed during the reaction.
摘要:
Organosols of organopolysiloxanes are prepared by adding water-soluble organic solvents or mixtures thereof or water-soluble mixtures of water-soluble and water-insoluble organic solvents to aqueous, colloidal suspensions of organopolysiloxanes obtained by adding at least one alkoxysilane and/or the partial hydrolyzate thereof, and, if appropriate, mixed with an organo(poly)siloxane free of alkoxy groups and having a maximum of 8 siloxane units per molecule, to water in the presence of emulsifiers at a maximum rate of 5 moles of organosilicon compound per hour and per liter of water, and subsequently removing the water by distillation.
摘要:
The invention relates to compounds of the formula[RSiO.sub.3/2 ].sub.z (I)in whichz is 6, 8 or 10;R represents the same or different radicals of the formulas--CH.sub.2 CH.sub.2 --X (II), --CH(CH.sub.3)--X (III) or --O--Si(R'.sub.2)--Y (IV) with the proviso that up to z-1 of the radicals can also be radicals of the formula --O--SiR'.sub.3, in which X represents a monovalent radical or one half of a divalent radical of the formulas ##STR1## R' represents the same or different C.sub.1 - to C.sub.6 -alkyl, C.sub.1 - to C.sub.6 -alkoxy or phenyl radicals;R" represents the same or different C.sub.1 - to C.sub.18 -alkyl radicals, which can be substituted by radicals of formulas (V) or (VI);R'" represents the same or different divalent C.sub.1 - to C.sub.18 -hydrocarbon radicals, preferably alkylene and/or phenylene radicals and/or radicals of the formula--(R'.sub.2 SiO).sub.n --;Z represents a halogen atom or an N-bonded amino radical, that is an NH.sub.2 radical, an N-piperidinyl, n-piperazinyl or N-morpholinyl radical or a C.sub.1 - to C.sub.6 -N-monoalkylamino or a C.sub.1 - to C.sub.6 -dialkylamino radical;Y represents a hydrogen atom, an optionally halogenated C.sub.2 - to C.sub.10 -hydrocarbon radical or a radical of the formulas (II) or (III); andn represents an integer having avalue of at least 1.
摘要:
Substrates which are exposed to weathering are coated with paints containing an epoxy resin and a silicon compound containing basic nitrogen which is bonded to the silicon via a carbon and which has at least one hydrogen atom bonded directly to the nitrogen atom.
摘要:
Extremely high solids content silica dispersions are useful for forming green bodies of near net shape as compared to the shape of the bodies after sintering. The green bodies are particularly useful for sintering to form low impurity-containing crucibles for single crystal silicon production.
摘要:
The invention relates to aliphatically unsaturated organosilicon compounds having 2 to 17 silicon atoms, to processes for their preparation and to their use in crosslinkable organopolysiloxane compositions, especially in compositions which can be crosslinked peroxidically or by hydrosilylation.