Bayer Aktiengesellschaft

Hans-Theo Van Pey

Dirk Berkenhaus

Peter R Nyssen

Wolfram Wagner

Roger Nyssen

Karl-Heinz Schott

Ewald Strzelczyk

Gunter Espanion

Gunter Haladuda

The process for the production of mineral wool fibres is based on melt streams 1 issuing from a melt distributor 3 being reduced to fibres in a drawing nozzle 9 by a blast medium flowing with high velocity in the axial direction. The blast medium charged with fibres then arrives in a subsonic diffuser 11 in order to reduce the flow velocity. The fibre-charged stream 10 is subsequently led onwards in a rectangular shaft 13. To separate non-fibrous constituents (so-called shots), a plurality of gas jets 18 are blown in at the shaft end transversely to the main flow direction at an angle .alpha. of 30.degree. to 120.degree.. As a result the fibre-charged stream is deviated. The stream 22 deviated in a direction of .beta.=60.degree. to 140.degree. is then picked up by a fibre shaft 21 mounted at the same angle .beta. and led to a deposition belt 23. The non-fibrous constituents (shots) 19, on the other hand, owing to their lower air resistance and higher inertia, fall through between the gas jets 18 and reach the lower discharge shaft 20.

Process for the production of mineral wool fibres of low shot content

The process for the production of superfine polymer fibre novwoven fabrics is based on spinning out radically the molten polymer at supply pressure in a rotating nozzle head (6) through a plurality of discharge opening (27) to form fibres and deflecting in the axial direction the not yet completely solidified fibres at a radial distance of 10 mm to 200 mm from the discharge holes (27) by an outer gas stream (8) and afterwards depositing them as nonwoven fabric (15) on a circulating, air-permeable carrier (12). In addition to the outer gas stream (8) an inner gas stream (24) emerges at a lower velocity from a plurality of axial boreholes (23) in the nozzle head (6) at a smaller radial distance than the discharge holes (27). Owing to the centrifugal sweeping forces at the rotating nozzle head (6) a rotationally symmetrical flow field then developes with a predominantly radial velocity component, the temperature of the gas being equal to or greater than the nozzle head temperature.

Process for the production from thermoplastic polymers of superfine

The polymer granular melt (1) is whirled out of a rotating nozzle head (6) through a plurality of exit holes (24) with fibre formation (32) and the fibres formed (9) are deposited on a collecting surface (12) in web form (15). This polymer melt is introduced into the nozzle head (6) under a preliminary pressure of 1 bar to 200 bar, preferably 1 bar to 50 bar. Furthermore, the fibres (32) are deflected by a high-speed gas stream (7, 8) in a radial direction at a radial distance of 10 mm to 200 mm from the exit holes (24) and, in the course of being deflected, are simultaneously drawn and stretched. The melt streams (32) exiting from the exit holes (24) can be additionally drawn by gas streams (26, 34) exiting in the vicinity of the exit holes (24) at the nozzle head (6) with a predominantly radial component before coming under the influence of the axial deflecting gas stream (7, 8).

Production of very fine polymer fibres

The streams of melt issuing from the melt outlet apertures (18) at the bottom of a melting crucible (14) are broken up into fibers in a drawing nozzle by means of a blast medium directed substantially parallel to the streams of melt. The blast medium is produced by a pressure gradient in the drawing nozzle and sucked in at the drawing nozzle inlet (7). In the drawing nozzle (16), the flow velocity is reduced in a downstream diffuser after the drawing process. The blast medium is supplied in the form of a hot gas between the underside of the crucible and the top edge (15) of the drawing nozzle from opposite broadsides of the melt distributor (14) in excess to the total quantity of gas stream sucked in at the drawing nozzle inlet (7). The hot gas consists of a mixture of combustion gases and air and is at a temperature from 600.degree. C. to 1500.degree. C., preferably from 800.degree. C. to 1400.degree. C. The flow velocity of the hot gas is adjusted to a value below 100 m/s, preferably 50 m/s, in the region (13) between the drawing nozzle (16) and the melt distributor (14). Gas burners (1) provided for producing the hot gas are arranged with their combustion chambers (3) situated laterally between the melt distributor (14) and the top edge (15) of the debiteuse. The combustion chambers (3) are connected by bores (6) to air chambers which are under an excess pressure. In the combustion chambers (3), the combustion gases are homogeneously mixed with the air introduced.

Process and apparatus for the production of very fine mineral fibers, in

Filaments of a molten material issue from a plurality of openings in a heated melt crucible and are further fiberized in a draw nozzle by means of a blowing medium. The diameter of the outlet openings (3) at the base of the melt crucible (1) is very small and is 0.2 to 1.5 mm, so that very fine primary filaments (12) are already formed at this point. These primary filaments are grasped by a very turbulent current at the entrance of the draw nozzle (5). The transverse component of the current decreasing in favor of the longitudinal component as the axial distance from the outlet openings (3) increases. The draw nozzle also has an inlet portion, which has a sharp outer edge and widens in the direction of flow, so that air blows against the primary filaments at a high speed and they are exposed to a strong pressure gradient in the longitudinal direction before entering the inlet portion. In the draw nozzle the primary filaments which are themselves already very thin are drawn out further until they have the required final diameter. For this purpose a zone is provided in the interior of the nozzle, following the inlet portion, in which zone the rate of flow of the blowing medium is 400 m/s to 600 m/s at a pressure of between 0.1 and 0.4 bar. By means of this device very fine mineral fibres with a substantially uniform fibre diameter of between 0.1 .mu.m and 5 .mu.m can be produced.

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Lipp, Germany

Hans-Theo Van Pey