Process for preparing amorphous silica submicron fibers and amorphous silica submicron fibers prepared thereby

• Main Authors: Hromádko Luděk, Bulánek Roman, Koudelková Eva, Buk Jan, Macák Jan M, Tejkl Miroslav
• Format: Patent
• Language: Czech; English
• Published: 21.12.2016
• Subjects: APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBONFILAMENTS; CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS,THREADS, FIBRES, BRISTLES OR RIBBONS; CHEMISTRY; COMPOUNDS THEREOF; INORGANIC CHEMISTRY; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT THEREOF; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MECHANICAL METHODS OR APPARATUS IN THE MANUFACTURE OFARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES ORRIBBONS; METALLURGY; MIXING, e.g. DISSOLVING, EMULSIFYING, DISPERSING; NANOSTRUCTURES FORMED BY MANIPULATION OF INDIVIDUAL ATOMS,MOLECULES, OR LIMITED COLLECTIONS OF ATOMS OR MOLECULES ASDISCRETE UNITS; NANOTECHNOLOGY; NATURAL OR ARTIFICIAL THREADS OR FIBRES; NON-METALLIC ELEMENTS; PERFORMING OPERATIONS; PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL; SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; SPINNING; TEXTILES; TRANSPORTING

Při způsobu přípravy submikronových vláken amorfního oxidu křemičitého o průměru 500 nm až 3000 nm se nejprve připraví prekursorní roztok, který obsahuje 1,1 až 24 hm. % tetraetyl orthosilikátu nebo tetrametyl orthosilikátu nebo jejich směsi jako prekursoru SiO.sub.2.n.4 až 20 hm. % polyvinyl pyrolidonu s molární hmotností 40 000 až 1 300 000 g/mol nebo polyvinyl alkoholu s molární hmotností 31 000 až 186 000 g/mol nebo jejich směsi jako nosného polymeru. Hmotnostní poměr prekursoru nebo směsi prekursorů SiO.sub.2.n.a nosného polymeru nebo směsi polymerů v prekursorním roztoku je 0,1:1 až 3:1, 2 až 4 hm. % kyseliny mléčné jako stabilizační činidla, 2 až 4 hm. % kyseliny mléčné jako stabilizačního činidla, 2 až 87,9 hm. % etanolu a 5 až 50 hm. % n-butanolu, jako rozpouštědla. Poté se tento prekursorní roztok odstředivým zvlákňováním přetvoří na prekursorní vlákna, která se kalcinují při teplotě 300 až 1400 .degree.C, čímž se z nich odstraní jejich organické komponenty a prekursor/prekursory SiO.sub.2.n.se přetvoří na amorfní SiO.sub.2.n., který si zachová vlákennou strukturu prekursorních vláken. The process for preparing submicron fibers of amorphous silica with diameter in the range of 500 to 3000 nm according to the present invention is characterized in that there is first prepared a precursor solution containing 1.1 to 24 percent by weight of tetraethyl orthosilicate or tetramethyl orthosilicate or a mixture thereof as SiOi2i precursor, 4 to 20 percent by weight of polyvinyl pyrolidone with molecular weight in the range of 40 000 to 1 300 000 g/mol or polyvinyl alcohol with molecular weight in the range of 31 000 to 186 000 g/mol or a mixture thereof as a carrier polymer. The weight ratio of the SiOi2 precursor or that of the SiOi2 precursor mixture and that of the carrier polymer or a mixture of polymers in the precursor solution is in the range of 0.1:1 to 3:1, 2 to 4 percent by weight of lactic acid as a stabilizing agent, 2 to 87.9 percent by weight of ethanol and 5 to 50 percent by weight of n-butanol as a solvent. Subsequently, the above-indicated precursor solution is transformed by centrifugal spinning to precursor fibers, which are calcined at a temperature in the range of 300 to 1400 degC, to thereby removing their organic components therefrom and the SiOi2 precursor/precursors are transformed to amorphous state, which retains fibrous structure of the precursor fibers. The invention also relates to submicron fibers of amorphous silica with diameters in the range of 500 to 3000 nm that are prepared in the above-described process and which have specific area greater than 100 me2/g, preferably greater than 500 me2/g.