U.S. patent application number 10/521532 was filed with the patent office on 2006-06-15 for device and method of liquid-permeable perforation of a nonwoven.
Invention is credited to Mathias Muth, Ralf Sodemann.
Application Number | 20060128245 10/521532 |
Document ID | / |
Family ID | 30010035 |
Filed Date | 2006-06-15 |
United States Patent
Application |
20060128245 |
Kind Code |
A1 |
Muth; Mathias ; et
al. |
June 15, 2006 |
Device and method of liquid-permeable perforation of a nonwoven
Abstract
A method for the manufacture of a perforated nonwoven, whereby
perforation means engage into the nonwoven. The perforation means
are arranged on a first roller. The perforation means engage
through the nonwoven into a surface of a second roller. The
perforation means displace fibers of the nonwoven, whereby the
perforation means engage in a material on the second roller, such
that said means can displace the material when they engage. In
addition, a corresponding device and corresponding materials are
provided for.
Inventors: |
Muth; Mathias; (Wiesbaden,
DE) ; Sodemann; Ralf; (Peine, DE) |
Correspondence
Address: |
ALSTON & BIRD LLP;BANK OF AMERICA PLAZA
101 SOUTH TRYON STREET, SUITE 4000
CHARLOTTE
NC
28280-4000
US
|
Family ID: |
30010035 |
Appl. No.: |
10/521532 |
Filed: |
July 5, 2003 |
PCT Filed: |
July 5, 2003 |
PCT NO: |
PCT/EP03/07217 |
371 Date: |
August 19, 2005 |
Current U.S.
Class: |
442/327 |
Current CPC
Class: |
D04H 3/14 20130101; D04H
1/56 20130101; D04H 1/12 20130101; Y10T 442/60 20150401; D04H 3/007
20130101; B26F 1/24 20130101; D04H 3/16 20130101; D04H 1/559
20130101; D04H 1/54 20130101 |
Class at
Publication: |
442/327 |
International
Class: |
D04H 13/00 20060101
D04H013/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 16, 2002 |
DE |
10232148.5 |
Claims
1. A method for the manufacture of a perforated nonwoven, wherein
perforation means engage into the nonwoven, the perforation means
are arranged on a first roller, and the perforation means engage
through the nonwoven into a surface of a second roller, the
perforation means displace the fibres of the nonwoven, whereby the
perforation means engage in a material on the second roller (10),
which they can displace during the engagement, and whereby contours
are formed in the material.
2. The method according to claim 1, wherein the perforation means
engage into an at least partially fibrous material, which for
preference forms the surface of the second roller.
3. The method according to claim 1, wherein the perforation means
are heated up to a temperature which is below a melt temperature of
the nonwoven or a decomposition temperature of the material.
4. The method according to claim 1, wherein a felt material is
used.
5. The method according to claim 4, wherein the felt material is
located onto the second roller as a shrinkage hose-type
covering.
6. The method according to claim 1, wherein the perforation means
displace the fibres of the nonwoven and push against the material
whereby the fibres are compacted and an opening in the nonwoven is
stabilised.
7. The method according to claim 6, wherein, when the perforation
means engage, fibres are at least in part forced out of the
nonwoven, whereby the fibres form a structure which correspondingly
exhibits a geometry of the perforation means, which, after the
nonwoven has run through the first and second roll, rises from a
surface of the nonwoven.
8. The method according to claim 6 wherein, when the perforation
means engage into the material, fibres are at least in part drawn
in sympathy into the material.
9. The method according to claim 1, wherein the perforated nonwoven
is detected.
10. A roll calender for the perforation of a nonwoven, whereby the
roll calender exhibits a first and a second roller, the first
roller has perforation means which project from a surface of the
first roller, and the first and the second rollers form a gap,
through which the nonwoven which is to be perforated is guided,
wherein the second roller exhibits a material as its surface which
can be displaced by the perforation means, whereby the gap is set
in such a way that the perforation means engage into the material,
and whereby contours are formed in the material of the second
roller.
11. The roll calender according to claim 10, wherein the gap is
capable of being changed.
12. The roll calender according to claim 10, wherein the material
exhibits fibres at least in part.
13. The roll calender according to claim 10, wherein the material
exhibits a felt material.
14. The roll calender according to claim 13, wherein the felt
material exhibits a thickness of at least 6 mm.
15. The roll calender according to claim 13 wherein the felt
material is a shrinkage hose covering.
16. The roll calender according to claim 13 wherein the felt
material is arranged under mechanical tension on the second
roll.
17. The roll calender according to claim 13, wherein a connection
material is applied on the second roll, which creates a connection
between the felt material and the second roll.
18. The roll calender according to claim 10, wherein the second
roll is driven.
19. The roll calender according to claim 10, wherein the
perforation means are needles which are capable of perforating the
nonwoven in such a way as to render it permeable to fluids.
20. The roll calender according to claim 10, wherein a carrier is
drawn onto the second roller, on which the material is
arranged.
21. The roll calender according to claim 10, wherein a detector
unit is arranged at the roll calender, which detects the perforated
nonwoven.
22. The roll calender according to claim 10, wherein the roll
calender exhibits a changeover device for changing the second
roller which is engaged with the first roller by a third
roller.
23. The roll calender according to claim 10, wherein the roll
calender exhibits a lateral possibility of access at the second
roll for drawing the felt material up and off.
24. (canceled)
25. (canceled)
26. (canceled)
27. A perforated nonwoven manufactured by a method according to
claim 1 in which the nonwoven, has a connecting surface which
amounts to between 8% and 25%.
28. (canceled)
29. (canceled)
Description
[0001] The present invention relates to a method of manufacturing a
perforated nonwoven, perforation means, particularly needles,
engaging in the nonwoven. The needles are positioned on a first
roller, the needles engaging through the nonwoven in a surface of a
second roller. Furthermore, a roll calender for perforating a
nonwoven is provided, the roll calender having a first roller and a
second roller. The first roller has perforation means. A perforated
nonwoven material is also. described, which is produced using a
method and/or a roll calender.
[0002] Calenders which each have a needle roller and a perforated
roller are described in European Patent Application 1 048 419 A1
and in European Patent Application 1 046 479 A1. The needles of the
needle roller engage in the corresponding diametrically opposite
openings of the perforate roller and are thus capable of
perforating material guided through the gap formed by the
perforated roller and the needle roller. Materials which may be
perforated are to be plastic films, paper, or nonwoven materials.
The latter are to be able to be up to a few millimeters thick.
[0003] The object of the present invention is to provide a method
and a device which allow the technical outlay for manufacturing
perforated nonwoven to be kept low, but simultaneously allow high
production speed.
[0004] This object is achieved by a method of manufacturing a
perforated nonwoven having the features of claim 1 and by a roll
calender for perforating a nonwoven having the features of claim
10. Further advantageous embodiments are specified in the
particular subclaims.
[0005] EP 0 598 970 A1 discloses a device and a method for
producing a perforated web, for example, a membrane material. In
the process, the web advances between two counterrotating
cylinders, of which a first cylinder is smooth and a second
cylinder is provided with projections. The second cylinder rotates
at a greater peripheral speed than the peripheral speed of the
smooth cylinder. The smooth cylinder comprises an elastically
yielding covering of a rubber material or textile fibers. The
different peripheral speeds of the cylinders produce a slipping
action, which creates in the web holes and forms around them
strands of partially detached material. These strands extend in the
direction, in which the membrane material passes between the two
cylinders. The function of the strands consists in allowing liquid
to pass from the one side of the membrane to the other, and
preventing the liquid from flowing back in the opposite
direction.
[0006] EP 0 214 608 A2 describes perforated spunbonded nonwovens of
polypropylene fibers and bicomponent fibers. In this connection, it
discloses a method of perforating a nonwoven, wherein a positive
roller mounts a plurality of perforation needles, which are brought
into contact with a counter roller. The nonwoven is perforated in
that the perforation needles enter the cavities of the counter
roller and in so doing penetrate the nonwoven. The nonwoven has
perforations with diameters ranging from 0.015 to 0.125 of an inch.
However, only 20% to 55% of the entire surface is perforated.
[0007] WO9967454 discloses a method for producing from fibers a
nonwoven material with a plurality of perforated hole structures
extending over the cross section of the nonwoven.
[0008] The perforated hole structures are produced by laying the
fibers on a screen belt to a fibrous web, by subsequently
perforating the fibrous web in a perforation mechanism, and
converting it into a nonwoven in a bonding unit. To this end, the
perforation mechanism comprises two elements. One element possesses
a plurality of spikes directing toward the fibrous web. The second
element possesses openings, into which the spikes of the first
element immerse in part, and displace without damage the fibers of
the fibrous web while passing therethrough, thereby forming the
hole structures. The openings of the second element connect to a
source of overpressure and vacuum, which permits taking into the
openings or blowing out therefrom fibers that are in the region of
the openings. Nonwovens produced therefrom have hole structures
with a diameter from 0.5 mm to 5 mm and 40 to 120 bonding points
per square centimeter, with the bonding surface being 10% to 40% of
the surface of the nonwoven material.
[0009] WO03004229 discloses a nonwoven fabric perforating device
according to FIGS. 1 and 2 and the description of the Figures at
pages 11 and 12. The device comprises a perforating roller 4 with
needles and a counter roller 5. The counter roller 5 includes a
coating 14, preferably a rubber coating. The needles of the
perforating roller are able to penetrate the coating of the counter
roller preferably to a depth from 2.5 mm to 6 mm. Likewise, the
coating 14 itself may contain holes that are arranged in facing
relationship with the needles 11.
[0010] WO03004259 discloses a perforating device, wherein a first
roller with a positive structure engages a second roller with a
negative structure and perforates a nonwoven in this process.
[0011] For example, a counter roller 3 shown in FIG. 1 comprises,
preferably on its surface, openings 14 that extend into the counter
roller 3. In their dimensions, the openings 14 approximately
correspond to the projections 5 of the perforating roll 2. The
openings may be circular holes, elongate holes, or, however, also
channels, as result, for example, from forming ridges on the
surface of the counter roller 3. A thermoplastic structure 7 is
formed by the interaction of the perforating roller 2 and the
counter roller 3.
[0012] The present invention relates to a method of manufacturing a
perforated nonwoven, perforation means, particularly needles,
engaging in the nonwoven. The needles are positioned on a first
roller, the needles engaging through the nonwoven in a surface of a
second roller. Furthermore, a roll calender for perforating a
nonwoven is provided, the roll calender having a first roller a
second roller. The first roller has perforation means. A perforated
nonwoven material is also described, which is produced using a
method and/or a roll calender.
[0013] Calenders which each have a needle roller and a perforated
roller are described in European Patent Application 1 048 419 A1
and in European Patent Application 1 045 479 A1. The needles of the
needle roller engage in the corresponding diametrically opposite
openings of the perforated roller and are thus capable of
perforating material guided through the gap formed by the
perforated roller and the needle roller. Materials which may be
perforated are to be plastic films, paper, or nonwoven materials.
The latter are to be able to be up to a few millimeters thick.
[0014] The object of the present invention is to provide a method
and a device which allow the technical outlay for manufacturing
perforated nonwoven to be kept low, but simultaneously allow high
production speed.
[0015] This object is achieved by a method of manufacturing a
perforated nonwoven having the features of claim 1 and by a roll
calender for perforating a nonwoven having the features of claim
10. Further advantageous embodiments are specified in the
particular subclaims.
[0016] A method according to the present invention for
manufacturing a perforated nonwoven provides that perforation
means, particularly needles, engage in the nonwoven. The needles
are positioned on a roller, the needles engaging through the
nonwoven into a surface of a second roller. The needles displace
fibers of the nonwoven, the needles engaging in a material. The
material is selected in such a way that the needles may displace
the material. In particular, the needles may displace the material
in such a way that contours form in the material. The needles
preferably engage reproducibly in these contours. The contours are
particularly first formed by the engaging of the perforation means.
The perforation means preferably at least partially engage in
fibrous material which preferably forms at least apart of a surface
of the second roller. The displaceable material is particularly a
felt material.
[0017] According to a refinement, the perforation means are
needles. The needles may have differing geometries and
cross-sections. For example, the needles may be pointed or blunt,
may have undercuts, and may be cylindrical or conical. The geometry
and the cross-section may change over the length of the needle. In
addition to needles, pyramids, stumps, particularly conical stumps,
mushroom geometries, oblong geometries having heads, at least
partially round heads, for example, may be used. The perforation
means may be milled, etched, or even eroded from the solid. The
perforation means may also be incorporated later, for example,
glued, clamped, or in another form-fitting and/or frictional
way.
[0018] The perforation means, particularly needles, preferably
engage in felt material which forms the surface of the second
roller. In this way, because the felt material is positioned on the
second roller, the felt material forms a counterpart diametrically
opposite the needles, which preferably may have an elastic
behaviour, but also has a certain hardness. The felt material is
preferably capable of stabilizing the nonwoven on the second
roller, so that the roller may laterally displace nonwoven fibers
as it slides into the nonwoven.
[0019] According to one embodiment, the felt material which is used
on the second roller is positioned on the second roller while
standing under mechanical tension. This particularly offers a
certain strength of the felt material in relation to a pressure
exerted by the needles and/or the first roller. Felt fibers are
also capable in this way of having a certain elastic behaviour.
[0020] According to one embodiment of the method, the first roller,
having the needles, is driven, while the second roller which has
the felt material on the surface is not driven directly. Rather, a
movement of the first roller ensures that the second roller is
carried along by the engagement of the needles in the nonwoven
material. In this way, the first roller and the second roller run
synchronously with one another. The felt material is preferably
selected in such a way that when the needles engage in the felt
material, this always occurs at approximately the same points.
Openings are thus formed within the felt material in which the
needles always engage. In this way, wear of the felt material when
it is used on the second roller is restricted.
[0021] According to a further embodiment, the needles are heated.
The heating is preferably to a temperature which lies below a
melting temperature of the nonwoven or a decomposition temperature
of the felt material. For example, a needle surface temperature may
be such that fibers of the nonwoven are melted and/or softened,
without, however, the fiber structure as such being destroyed. A
refinement of the method provides that the felt material is applied
to the second roller as a shrinkage hose. This shrinkage hose is
preferably seamless. The second roller preferably has a metal
surface. It may be smooth on its surface or have a corrugation. The
corrugation is, for example, applied as a spiral or in the form of
grooves with their axes parallel. There is also the possibility
that the surface of the second roller has screw-like grooves with a
left or right pitch. The particularly metal surface of the second
roller and the felt material are preferably connected in that the
hose exerts a pressure on the metal surface of the second roller.
Furthermore, an adhesive may also be applied between the felt
material and the metal surface. This adhesive may preferably be
dissolved again through the effect of alcohol or something similar,
for example. In this way, the connection between the film material
and the second roller may be removed again. If the felt material is
too worn, it is replaced with a new felt material. The remaining
parts of the second roller do not absolutely have to be
replaced.
[0022] A refinement, which also represents an independent idea,
provides that the felt material is applied to a carrier. The felt
material having the carrier is then subsequently applied to the
roller, pulled on, for example. The carrier is preferably a
changeover bobbin. The changeover bobbin is preferably pushed onto
the roller. The changeover bobbin and the roller are connected via
typical connections, which are particularly frictional and/or
form-fitting. For example, tongue and groove systems, screw
connections, or something similar may be used. The felt material is
preferably applied replaceably to the carrier, so that the carrier
is reusable. The carrier, in particular the changeover bobbin,
allows rapid felt material replacement. A standstill time of the
calender is thus minimized. The felt material and the carrier are
connected, for example, as was described above in the context of
the connection of the felt material to the roller. A plastic
material is preferably used for the changeover bobbin. A shrinkage
hose only has to be pulled onto the changeover bobbin. The rollers
of the calender may remain unchanged. By using multiple changeover
bobbins, even shorter useful lives of the felt material may be
overcome rapidly. Through a sufficient supply, replacement of the
changeover bobbin may be performed simultaneously with a
replacement of a roll from the unwinder.
[0023] According to a further and also independent idea of the
present invention, the roll calender is constructed in such a way
that the counter roller may be made accessible on one side in such
a way that, for example, a changeover bobbin may be replaced. This
is preferably performed while the other side remains in its
position, in a bearing, for example. If the weight of the counter
roller must be compensated for, a support may be provided on the
calender for this purpose. The support absorbs the weight which
would otherwise be produced by unclamping the now free side of the
counter roller. The support is preferably at least partially
movable so that there is sufficient protection as the changeover
bobbin is pulled off and on. A part of the support is particularly
movable along the axis of the counter roller. According to a
refinement, the counter roller is supported on the free side by an
attachable weight receiver. The weight receiver is screwed on, for
example, and extends along the axis of the counter roller. The
force receiver is particularly long enough that the sleeve may be
pushed on and off.
[0024] A further, also independent idea provides that the calender
has a roller changer for the counter roller. If, for example, a
first felt material is worn so much that it must be replaced, the
first counter roller having the first felt material is moved away
from the perforation roller and a second counter roller of the
calender having a second felt material is brought into contact with
the perforation roller. The first counter roller may now, for
example, be uninstalled in order to replace the first felt
material. For example, a roller changer for a calender is disclosed
in German Patent 100 05 306 C1, to which reference is made in its
entirety in the scope of this disclosure, particularly in regard to
the calender, the roller replacement, and the operation of the
roller.
[0025] A good pressure during the use of a felt hose results, for
example, if the felt hose is pulled over the cleaned surface of the
second roller or the cleaned carrier and subsequently is wetted
through with water heated to approximately 60-80.degree. C. In this
case, it may be advantageous to add an additional wetting agent to
the water, this may be a detergent, for example. In this way,
shrinkage of the felt hose is accelerated. Subsequently, the felt
hose is quenched using cold water and dried on the second roller at
a temperature of 30-40.degree. C., for example. The connection
between the felt material and the second roller and/or carrier
achieved in this way is sufficient that there is no slip between
the felt material and the second roller as the needles penetrate
into the felt material.
[0026] A surface of the felt material itself may also be processed.
This is necessary, for example, if the felt material surface has
elevations or appearances of wear, which cause interference. There
is also the possibility of either roughening the surface or
processing it in such a way that its degree of roughness decreases.
The latter may be performed, for example, using light singing of
protruding felt material fibers and subsequent removal using a
brush, for example.
[0027] A felt material which has wool as a fibrous material is
preferably used. For certain applications, however, it may also be
advisable to use other fibrous materials as the felt material.
These may be, for example, flax or cotton, viscose, polyamide,
polyacrylonitrile, polyester, polypropylene, aramid,
polytetrafluoroethylene, polyamide, or polyphenylene sulfide. While
wool has a long-term heat resistance of around 100.degree. C., at a
higher needle temperature, polyamide, polyester, or aramid fibers
are used, for example. Special durability of the shrinkage hose
used has resulted when it has a hardness of group F according to
DIN 61 200. The felt material preferably has a gross density
between 0.32 and 0.48 g/cm.sup.3. The felt material preferably has
a felt thickness which is greater than 5 mm, particularly greater
than 8 mm, preferably 10 mm and more, for example, up to 15 mm. A
felt hose is preferably used which has a wool felt according to F 2
having a wall thickness of approximately 10 mm and a density of
0.36 g/cm.sup.3.
[0028] Use of a felt hose and/or a felt material has the further
advantage that little consideration must be taken of temperature
expansion of the needle and/or of the first roller. Particularly if
the first roller carries along the second roller, the needles and
the engagement points in the felt material are automatically
synchronized. Furthermore, an embodiment provides that the material
of the second roller has a lower elasticity than the felt material
which forms the surface of the second roller. The second roller is
preferably manufactured from a metal, particularly an alloyed
steel. Another embodiment provides that the second roller has
plastic, and preferably is made predominantly of plastic.
Furthermore, the second roller may also be a hollow roller.
[0029] A gap between the first and the second roller is preferably
set in such a way that the needles which penetrate into the
nonwoven displace the fibers of the nonwoven and press against the
felt material, the fibers being compressed and an opening in the
nonwoven being stabilized. Depending on the speed of the rollers
and/or the nonwoven guided through them, the pressure applied, the
temperature, and other parameters, there is the possibility that
the openings will assume a funnel shape, for example. Furthermore,
the use of a felt material on the second roller allows the use of
greatly differing needle geometries. These may be pointed, conical,
blunt, or shaped in other ways. Their cross-sections may be
rectangular, star-shaped, round, semicircular, figure-shaped, or
even mixtures of all of these.
[0030] According to a refinement, the needles are particularly
shaped in such a way that as the needles engage, fibers are at
least partially displaced out of the nonwoven. In this case, the
fibers form a structure which deforms corresponding to a geometry
of the needles. The structure preferably arises from a nonwoven
surface after the nonwoven passes through the first and the second
roller. Another embodiment of the method provides that upon
penetration of the needles into the felt material, fibers are at
least partially also pulled into the felt material. As the nonwoven
is subsequently pulled off of the second roller, this may lead to
the existing texturing of the nonwoven surface becoming more
pronounced. For example, by adhering in the felt, the fibers may be
pulled out until the felt-fiber connection is broken.
[0031] According to a further idea of the present invention, a roll
calender for perforating a nonwoven is provided, the roll calender
having a first and a second roller. The first roller has
perforation means which project from a surface of the first roller.
The first and the second roller form a gap, through which a
nonwoven to be perforated is guided. The second roller has a felt
material as a surface, the gap between the first and the second
roller being set in such a way that the perforation means engage in
the felt material. A refinement provides that the gap between the
first and second roller is changeable. In particular, it may be set
in such a way that the needles used do not engage completely in the
felt material and the nonwoven guided through, but only up to a
certain range.
[0032] The needle roller preferably has a circular needle shape. A
needle diameter preferably has a value between 1 and approximately
3 mm. A needle area is particularly between 1.5 and 5 mm.sup.2, a
needle density is preferably between 8 and 25 per cm.sup.2, a
needle area component preferably being between 30% to 70%. An
insertion depth of the needles into the felt material is preferably
between 2 mm to 6 mm. The gap between the first and the second
roller is preferably set in such a way that the needles are not
inserted completely into the felt material and into the nonwoven. A
further embodiment provides that the gap has a size such that a
nonwoven guided between them is compressed simultaneously with the
perforation. For example, the nonwoven may be subjected to a
pressure and/or a temperature for this purpose, which is exerted by
the first roller or parts thereof on the nonwoven.
[0033] Data of an exemplary needle roller, using which various
nonwovens were perforated on the second roller in interaction with
a felt material, are listed in the following table. TABLE-US-00001
Needle Needle Needle Needles Needle shape in diameter area [number/
area top view [mm] [mm.sup.2] cm.sup.2] proportion [%] Circular
1.95 2.987 15.36 45.86
[0034] Exemplary measurement data of various experiments which were
determined using a needle roller and a felt-coated counter roller
are listed in the following table: TABLE-US-00002 Feed material A A
A B B B B Area weight 30 30 30 30 30 40 40 [g/mm.sup.2] Needle 4.5
4.5 5.0 4.5 5.0 4.5 5.0 insertion depth [mm] Hole area 0.63 0.68
1.09 0.73 0.84 0.91 0.95 [mm.sup.2] Open area [%] 9.7 10.6 18.3
12.3 14.2 15.1 15.7 A: polypropylene spunbonded nonwoven B:
polypropylene spunbonded nonwoven + polyethylene/polypropylene
bi-component spunbonded nonwoven In the experiments shown, the
screen belt speed was 95 m/minutes.
[0035] The perforation means, particularly the needles, are
preferably implemented in such a way that the nonwoven is
perforated so it is permeable to liquid. It has been shown to be
particularly suitable in this case to use a prebonded nonwoven as
the nonwoven used. A single-layer nonwoven is preferably used. For
example, a spunbonded nonwoven made predominantly of polypropylene
is used, which is single-layer. This spunbonded nonwoven preferably
has a weight between 20 g/m.sup.2 and 40 g/m.sup.2. The basic
weight is preferably around 30 g/m.sup.2. A prebonded nonwoven has,
for example, a bonded area in the form of thermobonding of 14.49%.
The nonwoven preferably has a bonded area between 10% and
approximately 60%. Besides thermobonding, the nonwoven may also
obtain its stability and strength through other bonding methods,
for example, through water jet bonding, adhesive, adhesive fibers,
ultrasound welding, etc. The hole sizes which were produced, for
example, were 1.09 mm.sup.2 as hole area, an average length being
1.35 mm in MD and an average length in CD being 1.04 mm. The needle
roller used was heated from the inside using a thermal oil for this
purpose, a surface temperature of the needle roller being set
between 105.degree. C. and 130.degree. C. Using the single-layer
nonwoven, hole sizes were achieved which had an axis ratio MD to CD
of approximately 1. Speeds of up to 95 m/minutes were used in this
case.
[0036] Further experiments were performed, for example, on a
two-layer nonwoven. A first layer was made of a spunbonded nonwoven
made of polypropylene, a second layer was made of a bi-component
material. The two-layer nonwoven was prebonded and had a bonding
area of approximately 17%. Especially good, stable circular
perforations resulted for a base weight which was between 30 and 40
g/m.sup.2.
[0037] A prebonded nonwoven which has a bonding area which is
particularly between 8% and 25% is preferably used for
perforation.
[0038] Besides the materials polypropylene and polyethylene cited,
the nonwovens may also have other materials, for example,
polyamides, polyester, glass fibers, PET, viscose, acetate,
polyacrylics, polystyrene, polyvinyl chloride, their copolymers,
and mixtures thereof. The use of bi-component or multicomponent
nonwovens made of these materials in particular is also
possible.
[0039] Further advantageous embodiment and refinements may be
inferred from the following drawing. The features illustrated there
may be combined with the embodiment of the present invention
described above into further independent refinements, without the
present invention being restricted as such in its embodiment by the
drawing.
[0040] FIG. 1 shows a first device for manufacturing a perforated
nonwoven,
[0041] FIG. 2 shows a detail from FIG. 1,
[0042] FIG. 3 shows a single-layer nonwoven before perforation,
[0043] FIG. 4 shows the single-layer nonwoven from FIG. 3 after
perforation,
[0044] FIG. 5 shows a two-layer nonwoven before perforation,
[0045] FIG. 6 shows the two-layer nonwoven from FIG. 5 after
perforation,
[0046] FIG. 7 shows a material, particularly a felt material, on a
changeover bobbin,
[0047] FIG. 8 shows a schematic view of a roll calender, in which a
roller in which the perforation means may engage is laterally
accessible to replace a surface material, and
[0048] FIG. 9 shows a schematic view of a further roll calender, in
which a replacement of rollers is possible.
[0049] FIG. 1 shows a first device 1 for manufacturing a perforated
nonwoven 2. A prebonded nonwoven 3 is guided from an unwinder 4
over various web guides 5 and a tension measuring roller 6 to a
roll calender 7. The roll calender 7 has a first roller 8 having
needles 9 as perforation means and a second roller 10. The second
roller 10 is preferably manufactured from metal and has a felt
material 11 on its surface. The felt material 11 is preferably a
shrinkage hose 12. The shrinkage hose 12 is pushed over the second
roller 10, so that an inner surface 13 of the shrinkage hose 12 is
in contact with a metal surface 14 of the second roller 10. The
surface 15 of the shrinkage hose 12 therefore simultaneously forms
an outer surface of the second roller 10. The needles 9 of the
first roller 8 engage in this surface 15. The prebonded nonwoven 3
is now guided to the roll calender 7 in such a way that it first
comes to rest on the second roller 10. The prebonded nonwoven 3
preferably has a looping angle around the second roller 10 of more
than 90.degree., particularly more than 120.degree., and preferably
more than 180.degree.. This allows tensions in the nonwoven to be
reduced due to the settling on the felt material 11 up to the
perforation by the needles 9. In particular, the not yet perforated
nonwoven 3 may be smoothed in this way. A defined tension is
preferably exerted on the nonwoven. The tension is, for example, at
least detectable via the tension measuring roller 6, and preferably
also adjustable via a position regulator.
[0050] It may also be seen from FIG. 1 that a gap 16 between the
first roller 8 and the second roller 10 is adjustable. At least one
of the two rollers 8, 10 may have its position changed. In this
way, a perforation depth of the needles 9 in the felt material 11
is adjustable. An adjustment of the perforation depth is checked,
for example, directly following the perforation by checking the
perforation image of the perforated nonwoven 2. This may
particularly be performed automatically. For example, a quality may
be checked immediately via a detection unit, preferably a camera
and preselectable parameters, and appropriate adjustments may be
undertaken in the event of deviations. For example, it may
additionally be indicated when the felt material must be replaced.
After the unperforated nonwoven 3 is perforated by the needles 9,
according to a further independent idea, the perforated nonwoven is
not immediately drawn out of the gap 16 and wound using a winder.
Rather, the nonwoven remains on the first roller 8 and is guided
further according to the rotation direction indicated by the arrow.
The perforated nonwoven 2 is preferably guided along over a looping
angle of greater than 90.degree., particularly greater than
120.degree., and preferably in a range from 160.degree. to
270.degree.. Only subsequently is the perforated nonwoven 2 pulled
off of the first roller 8 and therefore the needles 9. Guiding the
nonwoven in this way provides many advantages: firstly, the needles
may be heated sufficiently that the perforations in the nonwoven
stabilize. In this case, stabilization may be performed through a
more uniform, particularly also slower supply of heat to the
nonwoven fibers surrounding the needles 9. This makes it possible,
for example, to soften not only nonwoven fibers which are directly
in contact with the needles 9. Rather, a larger wrap angle
preferably also allows nonwoven fibers positioned neighboring
thereto to be at least softened. Softening preferably leads to
slight adhesion of the surfaces of fibers pressing against one
another. In this way, structures and geometries assumed may be
stabilized. In addition, nonwoven guiding of this type allows the
nonwoven fibers to be compressed against one another through the
engagement of the needles 9 in the perforated nonwoven 2 and the
further guiding of the nonwoven on the surface of the felt material
11. This also leads to stabilization of the perforation structure
generated in the nonwoven by the needles 9. The perforated nonwoven
2 is guided from the first roller 8 to a second tension measuring
roller 17. From there, the perforated nonwoven 2 reaches a winder
18 via web guides 5. The tension measuring roller 17 allows the
stresses applied to the nonwoven to be checked repeatedly during
the perforation procedure and the speed of the winder 18 and/or
unwinder 4 to be adjusted accordingly. Furthermore, the speed of
the first roller 8 and/or the second roller 10 may be regulated in
such a way that a desired tensile stress acts on the nonwoven.
[0051] FIG. 2 shows a detail from FIG. 1. The engagement of the
needles 9 in the felt material 11 of the shrinkage hose 12 may be
seen. An exemplary construction of the first roller 8 is
schematically indicated. The needles 9 are introduced into the
surface of the first roller 8. The possibilities of the
constructive achievement of the object of providing needles or
other perforation means in the first roller 8 are known in the
related art. For example, reference is made in the scope of this
disclosure to the documents in the related art cited above.
[0052] FIG. 3 shows a single-layer nonwoven 19, which is shown
perforated in FIG. 4. The single-layer nonwoven 19 is preferably a
spunbonded nonwoven. The perforations are particularly implemented
in such a way that the nonwoven fibers projecting from the surface
form funnel-shaped structures. FIG. 5 and FIG. 6 show a two-layer
nonwoven 20, which is either laminated together before the
perforation or is laminated together by the perforation procedure.
A first layer 21 and a second layer 22 are perforated
simultaneously. A formation of funnel-shaped structures of the
first layer 21 preferably extends in this case into the second
layer 22 in such a way that the latter has an approximately smooth
surface without further elevations. Depending on the penetration
depth of the needles, however, nonwoven fibers from the first layer
21 and/or the second layer 22 may also arise from a surface of the
two-layer nonwoven 20.
[0053] FIG. 7 shows a changeover bobbin 23, which is preferably
manufactured from plastic. A shrinkage hose is applied to the
changeover bobbin, for example, which particularly has a felt
material 11. The felt material 11 may be removed again from the
changeover bobbin 23, so that subsequently a new shrinkage hose may
again be placed on the changeover bobbin 23. Preferably, the
changeover bobbin 23 has a certain elasticity and/or deformability.
For example, in this way a pressure which acts on the changeover
bobbin 23 from the shrinkage hose may act from the changeover
bobbin 23 on a counter roller of the calendar positioned
diametrically opposite a perforation roller. In particular, the
pressure may be so great that in this way an attachment of the
changeover bobbin 23 on the counter roller is at least
supported.
[0054] FIG. 8 shows a schematic drawing of a calender 24, which is
laterally accessible. This allows replacement of a surface on the
second roller 10 without the second roller 10 having to be
uninstalled. A holder 25 and/or cover may be folded out laterally
for this purpose or displaced upward and/or downward. This allows
free lateral access to the second roller 10. In particular, the
roller construction of the second roller 10 and a corresponding
dimensioning and weight layout may be such that a holder on one
side in the calender 24 is sufficient to catch the weight of the
second roller 10. This may apply if the calender 24 is not in
operation, but also if the calender 24 is in operation. For
example, the second roller 10 may be a hollow roller, may be made
of light material, and/or may be at least partially made of plastic
or even aluminium. Using the ability to clamp on only one side, the
second roller 10 may also be pulled out of the calender frame and
the surface of the second roller 10 may be changed.
[0055] The construction and mode of operation of the schematic
drawing shown in FIG. 9 corresponds to that of the arrangement
known from FIG. 1. In addition, a principle is illustrated in FIG.
9, with which the second roller 10 may be replaced by a third
roller 26 through a replacement mechanism. In this way, for
example, the second roller 10 may be replaced while the third
roller 26 is engaged with the first roller 8. For this purpose, the
roll calender 7 has, in addition to the third roller 26, a lever
mechanism 27, for example, via which the second roller 10 and the
third roller 26 are connected to one another. If the lever
mechanism 27 is moved as indicated by the arrows around an axis
(not shown in greater detail), for example, the second roller 10
moves away from the first roller 8. The third roller 26, in
contrast, is moved toward the first roller 8. Fine adjustment of
the distance of the particular roller 10, 26 to the first roller 8
may preferably be performed independently of the lever mechanism
27. If the third roller 26 is engaged with the first roller 8, the
nonwoven to be perforated may be guided along the third roller 26
to the first roller 8 as indicated by the dashed lines. The tension
measuring roller 17 may preferably have its position tailored to
that of the third roller 26. In this way is ensured that tension
measurement occurs even during operation of the third roller
26.
* * * * *