Lenzing Aktiengesellschaft

Chemiefaser Lenzing Aktiengesellschaft

Heinrich Schmidt

Klaus Weinrotter

Susanna Schiemer

Johann Kalleitner

Jamal Salim

Reinhard Holzinger

Christoph Boxan

Thomas Jeszenszky

Siegfried Baumann

Josef Schmidtbauer

Arnold Verwanger

Hans Kalleitner

Daniel Thomas Blair

The present invention concerns a process for the manufacture of solid regenerated viscose fibers, comprising the steps of: &#x2014;spinning a viscose spinning dope through a spinneret comprising spinning holes into a regenerating bath thereby forming filaments, &#x2014;said viscose spinning dope having an alkali ratio immediately before spinning of from 0.7 to 1.0, preferably from 0.8 to 0.9, &#x2014;at least part of said spinning holes having a circular orifice, &#x2014;said regenerating bath containing&#x2014;from 70 to 120 g/l, preferably 90 to 110 g/l sulfuric acid, &#x2014;from 240 to 380 g/l, preferably 330 to 370 g/l sodium sulphate, &#x2014;from 20 to 50 g/l, preferably 25 to 35 g/l zinc sulphate and said regenerating bath having a temperature of from 45 to 55&#xb0; C., preferably 48 to 50&#xb0; C., &#x2014;stretching said filaments after leaving said regenerating bath in a secondary bath and/or in air at a stretching ratio of from 70% to 90%, preferably 80% to 90% of the maximum stretching ratio as hereinbefore defined and &#x2014;treating said filaments with a fatty acid ester.

Process for the manufacture of solid regenerated viscose fibers

There is disclosed a process for the electrodialysis of alkali sulfate-containing aqueous solutions in stages, by conducting these solutions through a plurality of electrodialytic cells operating in series. The electrodialytic cells include acid and base compartments and a cation exchange membrane. The alkali sulfate-containing aqueous solutions exclusively are conducted through acid compartments of the electrodialytic cells. The electrodialytic cells exclusively possess cation exchange membranes in their interiors and are delimited by bipolar ion exchange membranes.

Process and apparatus for electrodialysis of an alkali sulfate

Non-flammable, high-temperature resistant polyimide fibers have irregularly lobed or serrated cross-sections, a wool-like smooth hand and high brightness. They are produced by a dry-spinning process which is carried out in a spinning column, wherein a 20 to 40% solution of the polyimide is spun from spinnerets having circular orifices, the orifice numbers ranging from 20 to 800 and the orifice diameters from 100 to 300 .mu.m. An extrusion speed of between 20 and 100 m/min, a take-up speed of between 100 and 800 m/min, an amount of spin gas between 40 and 100 m.sup.3 /h under standard conditions and a spin gas temperature of between 200.degree. and 350.degree. C. are applied. The tows leaving the spinning column, which contain residual solvent from 5 to 25% by weight--based on dry polymer--and have a single filament titer of between 3.5 and 35 dtex, are washed in hot water, then they are dried to a moisture content of less than 5%, subsequently are drawn at high temperatures and, if desired, are crimpled and cut into staple fibers.

Non-flammable, high-temperature resistant polyimide fibers made by a dry

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Vöcklabruck, Austria

Heinrich Schmidt