Method for producing a spinnable silica sol material

A process for producing a spinnable silica sol material comprising:

• (a) stipulating a viscosity value VS, which the spinnable silica sol material should have after ripening, wherein the stipulated viscosity value VS is in the range from 30 to 100 Pa·s at a shear rate of 10 s−1 at 4° C.,
• (b) ascertaining a viscosity value VR corresponding to VS, which the silica sol material has before ripening,
• (c) combining an aqueous acid solution and a hydrolysable silicon compound, wherein the combining in (c) takes place under quasi-isothermal conditions over a period of at least 15 minutes, and wherein, in (c), the hydrolysable silicon compound is metered into an acid located in a solvent in parallel in a controlled manner,
• (d) evaporating a mixture combined in (c) to give a single-phase solution while measuring the viscosity of the mixture and terminating evaporation process upon reaching the viscosity value VR,
• (e) ripening a single-phase solution obtained in (d) to give a silica sol material with the viscosity value VS, wherein the ripening in (e) is carried out at temperatures of from 25° C. to 35° C., and wherein the single-phase solution is stirred;
• wherein the viscosity values VS and VR are dynamic viscosities, which are correlative and measured online and inline continuously by measurement probes within the mixture.