Note: Descriptions are shown in the official language in which they were submitted.
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Method for the Production of Geotextiles From Melt-Spun Fibers
The invention relates to a method for the production of geotextiles from melt-
spun fibers, in
which the melt-spun endless fibers ar a continuously transported in an
unimpeded manner
on a screen belt along all hardening and post treatment zones.
In DE 196 27 256, a method for the hydromechanical consuming of fibers of a
fiber web is
described, wherein a multiple needling occurs during alternating web guidance
and the
transfer from one to another transport device occurs by continuous and stretch-
free
supporting of the fiber web.
For this purpose, the fiber web is supported by a running endless web [sic;
conveyor belt?]
during the transport from one contact surface to the next.
From EP 0 859 076, a device for the hydrodynamic consumption of fibers of a
fiber web is
known, wherein, in order to achieve a stronger stitch-bonding, the
transporting endless
conveyor is assigned an endless conveyor guided in the opposite direction in
the first
needling unit, and the fiber web is increasingly solidified in the cone gap
foiming between
the endless conveyors.
Both methods should avoid disruptions in the not yet sufficiently hardened
fiber web.
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v~10 20044048667 CA 02507605 2005-05-26 pCT/EP2003/013310
However, the first disruptions in the fiber web already occur after the
depositing of the
fibers during the transport to the first hardening zone.
It was the task of the present invention to provide a method for the
depositing and
subsequent hydrodynamic consumption of the fibers, in which a disruption of
the fiber web
immediately after the depositing of the fibers before the first hardening zone
is also
avoided.
The subject matter of the present invention is therefore a method for
producing geotextiles
from melt-spun filaments by means of hydrodynamic consumption, characterized
in that the
melt-spun filaments are deposited on an endless screen belt and transported on
that screen
belt through the first hardening zone, wherein the filaments are additionally
fixated on the
screen belt by suction zones during the entire process and are therefore
already sufficiently
hardened in the first hardening zone, so that a disruption-free transport
without a transport
belt is possible.
The melt-spun fibers are therefore first deposited in the usual manner on the
endless screen
belt and transported on that screen belt to the first stitch-bonding stage. At
the same time,
the deposited filaments are fixated on the screen belt by suction zones during
the transport,
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so that no disruptions can occur during the transport of the unhardened
filaments. The speed
of the sucked air during this is 1-15 m/s.
In the first stitch-bonding stage, the water j ets act through the screen belt
and/or the screen
belt serves as a support, depending on the stitch-bonding device assembly.
For the construction variant of stitch-bonding through the screen belt, the
screen belt has a
mesh width of 1 - 8 cm ~, preferably 2 - 5 cm-1.
If the screen belt acts as a support, the screen belt has a mesh width of 10 -
100 cm-1,
preferably 20 - 60 cm-1.
After stitch-bonding in the first stitch-bonding stage, the geotextile is
sufficiently hardened,
so that it can also be guided without the support of a transport conveyor
without causing
disruptions of the structure.
If necessary, however, the screen belt can also be guided through any further
stitch-bonding
stages.
Thus, non-woven textile formation as well as the stitch-bonding takes place on
the screen
belt.
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By this method, it is possible to avoid any disruption in the structure of the
yet unhardened
geotextile after depositing.
Thus, complex process guidance like, for example, an alternating guidance, can
be avoided.
The geotextiles produced in this way are distinguished by a high homogeneity
and
regularity.
As filaments, all raw materials that can be melt-spun can be considered, for
example
polyolefines, such as polypropylene, polyamides or polyester.
Another subject matter of the present invention is a device for the production
of geotextiles
from melt-spun fibers, characterized in that a screen belt is guided beneath
the deposit
device, to which suction zones are attached, and that the screen belt is
guided to the first
hardening zone.
In Fig. 1 and Fig. 2, such devices are presented:
The following mean therein
1 - filament veil
2 - unhardened non-woven fabric
3 - transport zone with extractor
4 - compacting belt
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- water j et stitch-bonding unit
6 - extractor
7 - spinning belt
8 - stitch-bonded geotextile
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