Melt blowing die

Details Melt blowing die Melt blowing die

1999-05-20

2001-06-19

Davis, Robert (Department: 1722)

Plastic article or earthenware shaping or treating: apparatus

Means making particulate material directly from liquid or...

By means applying fluid jet or blast to unconfined liquid...

C425S072200

Reexamination Certificate

active

06247911

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an improved die for use in textile processes involving nonwoven melt blown fabrics. In a melt blown process, molten polymer resins are injected into a melt blowing die and ejected or extruded from the die in the form of filaments. The present invention is directed to an improved die faceplate in combination with an extension plate that provides an extended flow path for an air jet to extrude a molten polymer filament of a reduced diameter in the melt blowing process.
2. Description of the Prior Art
Prior art dies comprise a resin nosepiece comprising an outer surface, a tip, and a resin flow channel extending to the tip. These nosepieces are usually adjacent to one or more air channels such that a stream of air flowing through the air channel past the tip pulls and attenuates the molten filament. The drag force of the air stream places a tensile stress on the attenuated filaments, thereby reducing their diameter. An upper faceplate and a lower faceplate are placed in front of the nosepiece and spaced apart to define a faceplate slit such that polymer filaments extruded from the nosepiece may flow through the faceplate slit within the air stream.
In prior art nosepieces, once the filament is extended beyond the faceplate slit, it is exposed to the entrained air which reduce the force acting upon it. This reduction in drag force limits the amount of drag pull acting upon the filament in the melt blowing process, thereby limiting the final diameter of the filament.
SUMMARY OF THE INVENTION
The present invention is directed toward a melt blowing die comprising a resin nosepiece comprising an outer surface, a tip, and a resin flow channel extending to the tip.
The invention further comprises an air channel adjacent to the outer surface of the nosepiece. The air channel comprises a forward segment extending beyond the tip of the nosepiece.
The invention further comprises an upper faceplate and a lower faceplate, spaced apart to define a faceplate slit. The faceplate slit is aligned with the forward segment of the air channel such that resin filaments extruded from the nosepiece tip may extend through the forward segment of the air channel and the faceplate slit. Each faceplate further comprises an inner surface facing the tip and an outer surface facing away from the tip.
The invention further comprises an upper extension plate mounted on the outer surface of the upper faceplate and a lower extension plate mounted on the outer surface of the lower faceplate. The upper and lower extension plates are spaced apart to define a flow channel in alignment with the faceplate slit.


REFERENCES:
patent: 4908163 (1990-03-01), McAmish et al.
patent: 5080569 (1992-01-01), Gubernick et al.
patent: 5580581 (1996-12-01), Buehning
patent: 5695377 (1997-12-01), Triebes et al.
patent: 5976431 (1999-11-01), Mears

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