U.S. patent application number 10/169909 was filed with the patent office on 2003-06-05 for method and device for bonding a non-woven fibre produced by the air-lay method.
Invention is credited to Fleissner, Gerold.
Application Number | 20030101556 10/169909 |
Document ID | / |
Family ID | 7627904 |
Filed Date | 2003-06-05 |
United States Patent
Application |
20030101556 |
Kind Code |
A1 |
Fleissner, Gerold |
June 5, 2003 |
Method and device for bonding a non-woven fibre produced by the
air-lay method
Abstract
The conventional method for production of a multiple-layer,
non-woven fibre is by means of the air-lay method, with thermal
bonding using bonding fibres. The same method can be applied to a
composite non-woven fibre with an intermediate pulp layer. This
method of bonding does not reduce the later pilling wear and hardly
influences the inner composition of the layers of the composite.
According to the invention, the outer non-woven fibre is preferably
made from a bicomponent fibre and treated by hydrodynamic needling
for bonding, such that not just the surface is bonded, but also the
layers are bonded to each other.
Inventors: |
Fleissner, Gerold;
(Bahnhofstr, CH) |
Correspondence
Address: |
ANTONELLI TERRY STOUT AND KRAUS
SUITE 1800
1300 NORTH SEVENTEENTH STREET
ARLINGTON
VA
22209
|
Family ID: |
7627904 |
Appl. No.: |
10/169909 |
Filed: |
September 27, 2002 |
PCT Filed: |
January 16, 2001 |
PCT NO: |
PCT/EP01/00406 |
Current U.S.
Class: |
28/104 |
Current CPC
Class: |
D04H 1/49 20130101; D04H
1/556 20130101; D04H 1/498 20130101; D04H 13/00 20130101; D04H 1/54
20130101; D04H 1/48 20130101; D04H 18/04 20130101 |
Class at
Publication: |
28/104 |
International
Class: |
D04H 003/08; D04H
005/08 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 18, 2000 |
DE |
10001957.9 |
Claims
1. Method for strengthening a non-woven fabric, which has been
produced according to the air-lay method, comprising two outer
layers made of cut, thermally activatable fibres and one layer made
of cellulose fibres, such as super-absorbent pulp, which is
disposed between these outer layers, through continuous forming of
initially the lower layer, then overlaying with the pulp layer and
finally the top layer, characterised in that the two outer layers
of the composite non-woven fabric are formed from fibres, which are
from 8 to 10 mm maximum in length, and the three-layered non-woven
fabric is subjected to a hydrodynamic needling process for the
strengthening, that is to say also for the intimate bonding of the
layers, which are laid solely according to the air-lay method.
2. Method according to claim 1, characterised in that in addition
to the strengthening by means of the hydrodynamic needling process,
the composite non-woven fabric, which is formed solely according to
the air-lay method, is treated by means of a thermal strengthening
process.
3. Method according to claim 2, characterised in that the term
thermal strengthening includes the treatment of the non-woven
fabric, which is formed solely according to the air-lay method,
with every type of heat treatment, namely heat treatment, for
example, with hot air, more especially through-ventilation, with
infra-red, with calendering.
4. Method according to claim 2 or 3, characterised in that the
composite non-woven fabric, which is formed solely according to the
air-lay method, is thermally treated before and/or after the water
needling process for strengthening.
5. Method according to one of the claims 2-4, characterised in that
the thermal strengthening together with the drying of the non-woven
fabric, which is formed solely according to the air-lay method, is
executed after the water needling process.
6. Method according to one of claims 2-5, characterised in that at
the end of the strengthening process, the composite non-woven
fabric, which is formed solely according to the air-lay method, is
calibrated again.
7. Method according to one of claims 1-6, characterised in that the
hydrodynamic treatment is executed on both sides of the composite
non-woven fabric, which is formed solely according to the air-lay
method.
8. Device for executing the method in accordance with one of claims
1-7, comprising the following disposed one after the other in a
line a) at least three moulding heads working according to the
air-lay method, one for the first layer made of thermally
activatable fibres with a fibre length from 8 to 10 mm maximum, one
for the pulp and one for the top surface layer again for the
thermally activatable fibres with a fibre length of from 8 to 10 mm
maximum, and a b) non-woven fabric strengthening unit, which
comprises a hydrodynamic needling device (6, 7) and a drier
(8).
9. Device according to claim 8, characterised in that upstream of
the device for the hydrodynamic needling of a composite non-woven
fabric, which is formed solely according to the air-lay method, c)
is disposed a device (5) for the thermal strengthening.
10. Device according to claim 8 or 9, characterised in that
downstream of the device for the hydrodynamic needling of a
composite non-woven fabric, which is formed solely according to the
air-lay method, d) is disposed a device (8) for the thermal
strengthening.
11. Device according to claim 10, characterised in that the device
(8) for the thermal strengthening of a composite non-woven fabric,
which is formed solely according to the air-lay method, is provided
after the hydrodynamic needling initially for the drying of the
non-woven fabric.
12. Device according to one of claims 8-11, characterised in that a
calibrating device (9) is provided as the last unit for treating
the composite non-woven fabric, which is formed solely according to
the air-lay method.
13. Multi-layered composite non-woven fabric comprising two outer
layers, which are formed in accordance with the air-lay method from
fusion adhesive fibres, which are from 8 to 10 mm maximum in
length, such as more especially double component fibres or and
other fibres, such as high polymer fibres, between which layers is
laid a further layer made of super-absorbent pulp, which is also
produced according to the air-lay method, wherein this composite
non-woven fabric, which is formed solely according to the air-lay
method, is strengthened by means of the hydrodynamic needling.
Description
[0001] WO 97/30223 makes known an air-lay method for producing a
composite non-woven fabric, where a plurality of air-lay moulding
heads of the type according to EP 0 032 772 are disposed one behind
the other and produce a composite non-woven fabric from connecting
fibres, then cellulose fibres and again connecting fibres. This
type of production has the advantage of higher achievable speed
compared to the formation of card non-woven fabric. For
strengthening, a calender and a through-ventilation unit are
connected and the object of these is to attach the connecting
fibres to one another using heat.
[0002] This type of strengthening does not create a non-woven
fabric which meets the conditions in practice. The individual
layers have no cohesive strength, the non-woven fabric components
delaminate and split. The surfaces of the non-woven fabric are also
liable to wear and tear.
[0003] The object of the invention is to find a method, the fibres
from which should make up this type of non-woven fabric for the
air-lay method and subsequently to find how this fabric should be
strengthened to prevent, amongst other things, delaminating.
[0004] Proceeding from a method, where for the strengthening of a
non-woven fabric, which has been produced according to the air-lay
method,--comprising two outer layers made of cut, thermally
activatable fibres and one layer of cellulose fibres, such a
super-absorbent pulp, which is disposed between these outer layers,
through continuous forming of initially the lower layer, then
overlaying with the pulp layer and finally the top layer--simply
one thermal treatment is provided, it is provided according to the
invention to form initially the two outer layers of the composite
non-woven fabric from fibres which are from 8 to 10 mm maximum in
length and then to subject the three-layered non-woven fabric to a
hydrodynamic needling process for strengthening, that is to say
also for the intimate bonding of the layers, which are laid solely
according to the air-lay method. In an advantageous manner here,
the multilayered composite non-woven fabric comprises two outer
layers, which are formed according to the air-lay method from
fusion adhesive fibres, such as more especially double-component
fibres or and other fibres, such a high polymer fibres, between
which layers is placed another layer of super-absorbent pulp, also
produced solely according to the air-lay method, and whereby this
composite non-woven fabric, which is produced solely according to
the air-lay method, is subsequently strengthened by means of the
hydrodynamic needling process.
[0005] This type of non-woven fabric composition for the surface
layers and the type of strengthening by means of the water needling
process guarantees a surface which is free of pilling and linting,
but which, nevertheless, is porous to liquid and can also cover a
stronger, absorbent pulp layer. The two outer layers of this type
of non-woven fabric are intensively strengthened by the water
needling process and are also bonded to the pulp layer, which is
what the dreaded laminating of the fibre types after strengthening
prevents. For sufficient strengthening of the surface layers, both
the layers are preferably treated with the water needling process,
that is to say the composite non-woven fabric is needled on both
sides.
[0006] Solely hydrodynamic needling of a composite non-woven fabric
is made known by U.S. Pat. No. 5,413,849. In this case however, the
outer layers are deposited as card non-woven fabric, that is to say
they are made from considerably longer staple fibres, and the
central layer comprises resilient continuous fibres, which give the
entire composite non-woven fabric a stability. The outer card
non-woven fabric layers made of staple fibres can be replaced
partially by the short pulp fibres, which can also be laid using
the air-lay method. The same is valid in conjunction with WO
92/08834. In this case, a mixture of staple fibres and pulp fibres
are water-needled, nothing being stipulated about the length of the
fibres, however the fibres are not laid according to the air-lay
method.
[0007] The fusion adhesive fibres should be treated for further
bonding on each other and to each other by means of heat. The heat
also influences the required surface finish of the non-woven
fabric. In this respect, the double-component fibre is particularly
advantageous because it remains preserved as original fibre during
the heat treatment, whilst the normal fusion adhesive fibre can
fuse and shrink, which is disadvantageous for the forming of the
resistant surface. This measure of heating the fusion adhesive
fibres is already known through U.S. Pat. No. 5,240,764, however
not in conjunction with the double-component fibres. The heat
treatment can be effected in the most varied way; the essential
point is the fibres bonding well on the surface and transversely
through the surface non-woven fabric.
[0008] A device of the type according to the invention is
represented as an example in the drawing. Further inventive details
can be explained by way of this example. In which:
[0009] FIG. 1 is the side view of a continuous system for the
production and strengthening of a dry non-woven fabric, which has
been laid according to the air-lay method, and
[0010] FIG. 2 is a system similar to FIG. 1 with no thermo bonding
according to the lay method.
[0011] The non-woven fabric is initially formed from staple fibres
and pulp. The staple fibres must be cut short enough for them to be
laid according to the air-lay method, i.e. they are from 8 to 10 mm
maximum in length. The moulding head 1 is then charged with the
staple fibres for the base layer of the non-woven fabric. The
staple fibres are such that they can be brought to adhesion under
the influence of heat. More especially advantageous here are
double-component fibres, which have the advantage that they do not
shrink under the influence of heat, but remain preserved as fibre.
Onto the base non-woven fabric formed with the moulding head 1 then
comes the pulp layer with the moulding head 2, where applicable a
thicker pulp layer again with another moulding head (not
illustrated), and then the top surface layer made of staple fibres.
This composite non-woven fabric 4 then has to be strengthened and
up to now this has only been effected by means of thermo
bonding.
[0012] According to the system in FIG. 1, the non-woven fabric 4 is
first pre-strengthened by means of heat in the device 5. This can
be effected by means of hot air (through-ventilation), but also
with the application of infrared radiation or with calendering.
This pre-strengthening measure has the advantage of obtaining
better surface closure of the surface layers, which can prevent a
greater loss of pulp during the subsequent needling process. The
system shown in FIG. 2 does not have this pre-strengthening under
heat. Therefore, depending on the fibre and other conditions, the
pre-strengthening measure can be left out.
[0013] The composite non-woven fabric 4 is then acted upon by the
hydrodynamic needling process. As, in this case, we are talking
about a non-woven fabric with surface layers on both sides, it is
expedient to execute the strengthening process with the water jets
on both sides. This is why the needling arrangement is represented
in the Figures with two drums 6 and 7, which is only to indicate
that the non-woven fabric is to be conveyed in a meander-shaped
manner about the drums so that it can be acted upon on both sides
by the water jets. This water jet strengthening process not only
influences the surface of the composite non-woven fabric, but also
the deeper cohesive strength of the layers such that a subsequent
delaminating of the individual non-woven fabric layers no longer
occurs.
[0014] After the strengthening of the composite non-woven fabric
and also the bonding of the layers with each other by means of the
water jets, the non-woven fabric must be dried. For this purpose, a
through-ventilation drier 8, such as a sieve drum drier, is
advantageously advantageous. Finally, the non-woven fabric can be
calibrated again by means of the arrangement 9, as is only
represented in the system shown in FIG. 2.
[0015] This type of composite non-woven fabric is very economical
because it can be produced at high speeds, such as, for example,
400-500 m/min. A very absorbent product of 40-100 g/m.sup.2 can be
produced, as the pulp layer can be thick. At the same time, the
surface layers should be thin in relation to the pulp layer, for
example 10 gm.sup.2, whilst the pulp layer can be heavy at 60
g/m.sup.2. Through a combination of thermo bonding and water
needling, the surface is not only essentially free of linting and
pilling, but the non-woven fabric is also strengthened through and
through and this makes it difficult to separate the layers of the
non-woven fabric.
* * * * *