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Abstract

The present invention relates to a polyethoxysiloxane (PES) material to be obtained in that (a) a first hydrolysis condensation reaction of a maximum of one group X of one or more different Si compounds of the formula (I) SiX4 (I) in which the groups X are the same or different and represent hydroxy, hydrogen, or ethoxy (EtO), are catalyzed in an acidic fashion at an initial pH value of 0 to ≦7, is conducted in the presence of ethanol (EtOH) or an ethanol-water mixture as a solvent over a time period of 1 to 24 hours at a temperature of 0° C. to 78° C, (b) a second hydrolysis condensation reaction of the material obtained in step (a) is conducted while simultaneously removing the solvent by successive evaporation in a gas diffusion-tight container at a pressure of 100 to 1013 mbar, preferably at a slight negative pressure of 300 mbar to 800 mbar and a temperature of 50-78° C. until a drastic increase in viscosity (at a shear rate of 10 s⁻¹ at 4° C.) to 0.5 to 2 Pa·s until a constant weight is attained and a cyclotetrasiloxane of the general formula ((SiO(OH)_0,75(OEt)_1,25× 1/64H₂O)₄ and a molar mass of 4*approx. 114 g=approx. 456 g; (c) said PES material is cooled in a closed container over a time period from a few minutes to a few hours, and (d) the PES material obtained from step (c) is converted into an rPES material by a third hydrolysis condensation reaction.

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