Dynamit Nobel Aktiengesellschaft

Egon Lang

Wilhelm Nachtigall

Robert Buning

Bernhard Piotrowski

Joachim Stark

Bernhard Janser

Disclosed is a method of making fibrids from thermoplastics synthetics and copolymers thereof by expanding by vaporization, in the presence of a gaseous propellant, a polymer solution under elevated pressure and elevated temperature in a mixing nozzle under shear inducing conditions wherein the true or apparent solution of the polymer in solvent is expanded by the use of superheated steam having an average energy density of at least 50 watt-seconds per cubic centimeter in the mixing nozzle.

Method of making fibrids from thermoplastics

An apparatus for the continuous manufacture of filaments from polyvinylidene fluoride includes a screw extruder with a single-spindle screw surrounded by a coaxial barrel with a feed zone, a compression zone, a metering zone, and a mixing head zone for the plasticizing of the polyvinyldene fluoride and with a die outlet tool for shaping the filaments. The compression ratio of the screw is 1:1.2 to 1:2.5, and the screw is provided with single-flight and double-flight sections of identical pitch in alternating succession in the region of the compression zone. The mixing head zone is fashioned as alternatingly successive mixing zones and shear zones, of which there are provided, respectively, two to four zones and preferably three zones.

Screw-type extruder for polyvinylidene fluoride filaments

A process for the production of monofilaments of polyvinylidene fluoride is disclosed wherein polyvinylidene fluoride is plasticized in an extruder and fed to an extrusion die and passed through an extrusion nozzle orifice to enter a liquid cooling medium having a thermal conductivity of under 0.4 W/m .degree.K., a viscosity at 100.degree. C. of over 0.5 cp and a density at 100.degree. C. of over 1.1 g/cm.sup.3. Extusion is performed by passing the plasticized polyvinylidene fluoride over separate extrusion zones such as by passing the polyvinylidene fluoride over a first extrusion zone maintained at a first extrusion temperature and thereafter passing the polyvinylidene fluoride through a second extrusion zone maintained at a temperature of 10 to 30 percent higher than the preceeding extrusion zone. An apparatus for carrying out the process is also described.

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Troisdorf, Germany

Egon Lang