Extrusion process and an extrusion die with a central air jet

Claim 2

A thermoplastic material extrusion mechanism comprising a die head including therein: a centrally disposed high velocity gas delivery means adapted to continuously emit at least one jet of a gas having shear layers; at least one chamber for said thermoplastic material; thermoplastic material delivery means arranged adjacent and at least partly surrounding said centrally disposed high velocity gas delivery means for directing molten extruded thermoplastic material emitted from said thermoplastic material delivery means toward said gas jet, causing said extruded thermoplastic material to be introduced into the shear layers of said gas jet; and thermoplastic material conduit means communicating said at least one chamber with said thermoplastic material delivery means.

Claim 3

The mechanism according to claim 1 wherein said thermoplastic material delivery means comprises at least one first thermoplastic material extrusion opening and at least one second thermoplastic extrusion opening.

Claim 4

The mechanism according to claim 1 wherein said mechanism further includes a means for supplying said thermoplastic material to said at least one chamber.

Claim 5

The mechanism according to claim 2 wherein said at least one chamber comprises two chambers.

Claim 6

The mechanism according to claim 4 wherein said two chambers comprise a first chamber adapted to contain a first thermoplastic material and a second chamber adapted to contain a second thermoplastic material.

Claim 7

The extrusion mechanism according to claim 5 wherein a first conduit means is provided between said first chamber and said at least one first thermoplastic material extrusion opening and a second conduit means is provided between said second chamber and said at least one second thermoplastic material extrusion opening.

Claim 8

The extrusion mechanism according to claim 1 wherein said mechanism further includes a heater for raising the temperature of said thermoplastic material.

Claim 9

The extrusion mechanism according to claim 5 wherein said mechanism includes means for delivering said first thermoplastic material at a first pressure to said first chamber and means for delivering said second thermoplastic material at a second pressure to said second chamber.

Claim 10

The mechanism according to claim 5 wherein said mechanism includes a first heating device for raising the temperature of said first thermoplastic material to a first temperature and a second heating device for raising said second thermoplastic material to a second termperature.

Claim 11

The extrusion mechanism according to claim l, further including a means for introducing an additive to the gas passing through said high velocity gas delivery means.

Claim 12

The extrusion mechanism according to claim 10 wherein said means for introducing an additive to the pressurized gas comprises an additive delivery duct.

Claim 13

The extrusion mechanism according to claim 11 wherein said high velocity gas delivery means has an exit plane and the outlet end of said additive delivery duct extends outwardly from the exit plane of said high velocity gas delivery means.

Claim 14

13 The extrusion mechanism according to claim 11 wherein said high velocity gas delivery means has an exit plane and the outlet end of said additive delivery duct is recessed within the exit plane of said high velocity gas delivery means.

Claim 15

The extrusion mechanism according to claim 2 further including means to adjust the width of said first and said second thermoplastic material extrusion openings.

Claim 16

The extrusion mechanism according to claim 2 wherein said centrally disposed high velocity gas delivery means has a longitudinal axis which forms an included angle of between about 30 degress to less than about 90 degrees with each of said first and said second thermoplastic material extrusion openings.

Claim 17

The extrusion mechanism according to claim 2 wherein said centrally disposed high velocity gas delivery means comprises a slot having two elongated edges.

Claim 18

The extrusion mechanism according to claim 16 wherein said at least one first thermoplastic opening comprises a first row of apertures arranged parallel to one of the elongated edges and on one side of said slot and said at least one second thermoplastic opening comprises a second row of apertures arranged parallel to the other of the elongated edges and on the opposite side of said slot.

Claim 19

The extrusion mechanism according to claim 16 wherein said at least one first thermoplastic opening comprises a first slit arranged parallel to one of the elongated edges and on one side of said slot and at least one second thermoplastic opening comprises a second slit arranged parallel to the other of the elongated edges and on the opposite side of said slot.

Claim 20

The extrusion mechanism according to claim 1 wherein said thermoplastic delivery means comprises a slit and said centrally disposed high velocity gas delivery means comprises a plurality of capillary gas nozzles arranged within said slit.

Claim 21

The extrusion mechanism according to claim 1 wherein said centrally disposed high velocity gas delivery means comprises a nozzle of circular cross section, said nozzle arranged concentrically within a cylindrical opening, the inner surface of said cylindrical opening and the outer surface of said nozzle defining an annular extrusion opening.

Claim 22

The extrusion mechanism according to claim 1 wherein said centrally disposed high velocity gas delivery means comprises a nozzle of circular cross section and said thermoplastic material delivery means comprises a plurality of thermoplastic material extrusion openings arranged around the nozzle in spaced relationship to each other and to said nozzle.

Claim 23

The extrusion mechanism according to claim 1 wherein said thermoplastic material delivery means comprises an extrusion opening having a circular cross section and said centrally disposed high velocity gas delivery means comprises a plurality of capillary gas nozzles arranged within said extrusion opening.

Claim 24

The extrusion mechanism according to claim 1 wherein said thermoplastic material delivery means comprises at least one first thermoplastic material extrusion opening and at least one second thermoplastic material extrusion opening, said at least one chamber comprises a first chamber adapted to contain a first thermoplastic material and a second chamber adapted to contain a second thermoplastic material, said thermoplastic material conduit means comprises a first conduit means provided between said first chamber and said at least one first thermoplastic material extrusion opening and a second conduit means provided between said second chamber and said at least one second thermoplastic extrusion opening, said high velocity gas delivery means comprises a slot having two elongated edges and said at least one first thermoplastic opening comprises a first row of apertures arranged parallel to one of the elongated edges and on one side of said slot and said at least one second thermoplastic opening comprises a second row of apertures arranged parallel to the other of the elongated edges and on the opposite side of said slot, and said mechanism further includes means for delivering said first thermoplastic material to said first thermoplastic chamber at a first pressure, means for delivering said second thermoplastic material to said second thermoplastic material chamber at a second pressure, a first heating device to raise the temperature of said first thermoplastic material to a first temperature, and a second heating device to raise the temperature of said second thermoplastic material to a second temperature.

Claim 27

The method according to claim 24 wherein said at least one stream of a molten thermoplastic material comprises at least one first thermoplastic material stream and at least one second thermoplastic material stream and said thermoplastic material delivery means comprises at least one first thermoplastic material extrusion opening from which said at least one first thermoplastic material stream is extruded and at least one second thermoplastic material extrusion opening from which said at least one second thermoplastic material stream is extruded concurrently with said at least one first thermoplastic material stream such that said at least one first and second thermoplastic material streams merge with the shear layers of said at least one high velocity gas jet and form thereby at least one first thermoplastic fiber stream and at least one second thermoplastic fiber stream, respectively.

Claim 28

The method according to claim 25 wherein a first thermoplastic material is extruded from said at least one first thermoplastic material extrusion opening and a second thermoplastic material is extruded from said at least one second thermoplastic material opening, said first and said second thermoplastic materials differing from each other in physical properties.

Claim 29

The method according to claim 24 wherein said at least one high velocity gas jet includes a fluidized additive.

Claim 30

The method according to claim 27 wherein said fluidized additive includes a superabsorbent material.

Claim 31

The method according to claim 27 wherein said fluidized additive comprises wood pulp fibers.

Claim 32

The method according to claim 27 wherein said fluidized additive comprises staple fibers.

Claim 33

The method according to claim 27 wherein said fluidized additive is a liquid.

Claim 34

The method according to claim 27 wherein said fluidized additive is a gaseous additive.

Claim 35

The method according to claim 25 wherein said first and said second thermoplastic material streams merge with the shear layers of said high velocity gas jet forming an angle with said high velocity gas jet of about 30 degrees to less than about 90 degrees.

Claim 36

The method according to claim 25 wherein said first and second fiber streams formed in step (c) are directed onto a collecting surface, forming thereby a melt blown, nonwoven mat.