U.S. patent application number 12/363922 was filed with the patent office on 2009-05-28 for method for the manufacture of polyethylene-based, soft nonwoven fabric.
This patent application is currently assigned to Fiberweb Corovin GmbH. Invention is credited to Markus Haberer, Henning Rottger.
Application Number | 20090133813 12/363922 |
Document ID | / |
Family ID | 34683816 |
Filed Date | 2009-05-28 |
United States Patent
Application |
20090133813 |
Kind Code |
A1 |
Haberer; Markus ; et
al. |
May 28, 2009 |
METHOD FOR THE MANUFACTURE OF POLYETHYLENE-BASED, SOFT NONWOVEN
FABRIC
Abstract
The present invention concerns a method for the manufacture of
nonwoven fabric the fibers of which have polyethylene on at least
part of their surface, where the fibers are thermally bonded and
the non-woven fabric exhibits an abrasion of less than 0.5
mg/cm.sup.2, in particular of less than 0.4 mg/cm.sup.2, and an
embossed area fraction of less than 35%, in particular of less than
28%. Furthermore a device is made available for the manufacture of
a non-woven fabric, using a polyethylene-containing polymer, with a
take-down system underneath a spinning plate that causes the
take-down of the polyethylene, where the spinning plate has an L/D
ratio of between 4 and 9.
Inventors: |
Haberer; Markus; (Berlin,
DE) ; Rottger; Henning; (Braunschweig, DE) |
Correspondence
Address: |
ALSTON & BIRD LLP
BANK OF AMERICA PLAZA, 101 SOUTH TRYON STREET, SUITE 4000
CHARLOTTE
NC
28280-4000
US
|
Assignee: |
Fiberweb Corovin GmbH
|
Family ID: |
34683816 |
Appl. No.: |
12/363922 |
Filed: |
February 2, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11425340 |
Jun 20, 2006 |
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12363922 |
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PCT/EP2004/004640 |
Apr 30, 2004 |
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11425340 |
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Current U.S.
Class: |
156/167 |
Current CPC
Class: |
Y10T 442/608 20150401;
D01D 5/0985 20130101; D04H 1/54 20130101; D04H 3/16 20130101; Y10T
442/641 20150401; D01F 8/06 20130101; Y10T 442/637 20150401; Y10T
442/69 20150401; D04H 3/007 20130101; Y10T 442/681 20150401; Y10T
442/60 20150401; D01D 4/02 20130101 |
Class at
Publication: |
156/167 |
International
Class: |
D04H 3/16 20060101
D04H003/16 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 20, 2003 |
DE |
10360845.1 |
Claims
1. A method for the manufacture of a nonwoven fabric, the fibers of
which at least in part have polyethylene on their surface, where
after take-down from a spinning plate at a speed of at least 650
m/min, the fibers are further processed, where the polymer in the
extruder is heating to between 200.degree. C. and 250.degree. C.
and passes at this temperature through the spinning plate heated to
a temperature between 200.degree. C. and 250.degree. C., where the
polymer is divided into individual polymer threads through at least
4500 holes/m, where the polymer threads each pass through the
spinning plate on a passageway which is at least four times as long
as the diameter of the polymer threads.
2. A method according to claim 1, wherein the passageway is at
least four times as long as the diameter of a boring of the
passageway.
3. A method according to claim 1, wherein the polymer threads are
stretched with a take-down speed of between 3000 m/min and 4500
m/min.
4. A method according to claim 1 wherein the polyethylene is mixed
with another polymer as dry blend or compound before going into the
extruder.
5. A method according to claim 1 wherein the polymer threads are
deposited on a screen belt and are then thermally bonded by means
of a calendar, the rollers of which are heated to a different
extent.
6. A method according to claim 1 wherein the polymer threads are
thermally bonded at a surface temperature range of 112-140.degree.
C., with a consolidating area fraction below 35%.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This is a divisional application of U.S. application Ser.
No. 11/425,340, filed Jun. 20, 2006, which is a continuation of PCT
International application PCT/EP2004/004640, filed Apr. 30, 2004,
which claims priority from German Application No. 10360845.1, filed
Dec. 20, 2003.
BACKGROUND OF THE INVENTION
[0002] The present invention concerns a nonwoven fabric the fibers
of which have a polyethylene at least on their surface, with the
fibers being thermally bonded. Furthermore claimed is a device for
the manufacture of a nonwoven fabric using a
polyethylene-containing polymer, and a procedure for the
manufacture of a nonwoven fabric the fibers of which have
polyethylene at least on part of their surface.
[0003] Because of their multiple applications, nonwoven fabrics
have the most varied applications. Because of their multiple
influence parameters, these properties can often be determined only
by means of elaborate tests, where in addition to the effects of
the polymer material used, also machine effects, ambient conditions
and other parameters have to be taken into account. For instance, a
nonwoven fabric is obtained from WO 02/31245 A2 that presumably is
particularly soft. A nonwoven fabric is obtained based on multiple
experimental parameters that are supposedly manufactured with a
consolidation surface area of at least 30% of the nonwoven fabric
surface area and an abrasion coefficient of less than 0.30
mg/cm.sup.2. To make such a material possible, a pre-consolidated
nonwoven fabric is passed though a first and then a second
calender, where thermal bonding takes place in both calenders. In a
calender placed downstream, the material thus doubly consolidated
is stretched essentially in CD direction, before being spooled and
transported for further processing.
[0004] It is the task of the present invention to make available a
nonwoven fabric that on the one hand feels soft and on the other is
sufficiently robust for numerous applications; the manufacture of
the nonwoven fabric should be as economical as possible.
SUMMARY OF THE INVENTION
[0005] This task is accomplished by means of a nonwoven fabric
comprising the features of claim 1, in a device according to the
features of claim 17 and/or according to a method comprising the
features of claim 39. Other advantageous implementations and
further developments are indicated in the dependent claims.
[0006] In accordance with the invention, a nonwoven fabric is
proposed the fibers of which have a polyethylene at least on the
surface, where the fibers are bonded and the nonwoven fabric has an
abrasion rate less than 0.8 mg/cm.sup.2. The fibers preferably
consist essentially of polyethylene.
[0007] The nonwoven fabric is preferably thermally bonded only
once. According to one implementation the nonwoven fabric has an
abrasion resistance rate less than 0.2 mg/cm.sup.2, especially in
the range between 0.2 to 0.09 mg/cm.sup.2. A further implementation
comprises a nonwoven fabric with a consolidation area fraction of
less than 0.2 mg/cm.sup.2, especially less than 32%, preferably
less than 28% a preferred embodiment comprises a nonwoven fabric
with an abrasion rate of less than 0.3 mg/cm.sup.2 and a
consolidation area fraction of less than 30%. The nonwoven fabric
fibers have polyethylene at least on their surface, where the
fibers are thermally bonded and the nonwoven fabric shows an
abrasion of less than 0.5 mg/cm.sup.2, in particular of less than
0.4 mg/cm.sup.2, and an consolidated surface fraction of less than
23%, in particular of less than 20%. According to one of the
further developments, a nonwoven fabric can be manufactured with an
abrasion of less than 0.3 mg/cm.sup.2, preferably even of less than
0.2 mg/cm.sup.2 and in particular, of less than 0.1 mg/cm.sup.2. It
is also possible to keep the consolidated area fraction to below
16%.
[0008] The abrasion is here determined as follows:
[0009] In nonwoven fabrics the abrasion is determined using a
Sutherland Inc. Rub Tester, a standard instrument in the paper
industry. This instrument can for instance be obtained from the
Richard Schmitt Company, In der Einsteinstrasse 20, 64668 Rimbach.
The Tester is described in principle also in U.S. Pat. No.
2,734,375. The measurement principle provides that a surface of the
nonwoven fabric be treated with sandpaper under defined conditions
and the abrasion is determined gravimetrically. Abrasion is here
defined as follows: the gravimetrically determined mass of loose
fiber per unit surface area [mg/cm.sup.2].
[0010] To perform the abrasion determination, a Sutherland Inc. Rub
Tester with a 1 kg bearing load (AGS) is required, with a holder
for the sandpaper, an analytical balance with a precision of
.+-.0.0001 g, a dinking die and stamp press, and a 2 kg hand
roller. The materials required are:
[0011] Sandpaper (aluminum oxide), 320 grain, width 50.8 mm;
double-side adhesive tape, from 3M, Article No. 9195, hereinafter
called Tape 1; to collect the fibers, an adhesive tape, from 3M,
Article No. 3126c, hereinafter called Tape 2; silicone paper; metal
sheets to glue on the nonwoven fabric.
[0012] Sample preparation is performed before carrying out the
test. To this end a piece of nonwoven fabric of size 20 cm.times.5
cm is punched out using a dinking die. Care must be taken to verify
whether the nonwoven fabric is tested in the production direction
(MD), or in the direction perpendicular to the production direction
(CD). Thus, if the nonwoven fabric sample is to be tested in MD,
then the MD must be oriented parallel to the longer side of the
nonwoven fabric specimen. The test report must indicate whether the
test was performed in MD or CD. When handling the nonwoven fabric
specimen, care must be taken not to touch it with bare hands, to
avoid surface contamination. Tape 1 has adhesive sides that adhere
with different strengths. The more strongly adhering side is the
side that remains covered when the tape is let out. The nonwoven
fabric must be glued onto this side. To this end, the side that is
uncovered during the unwinding of Tape 1 must be covered with
silicone paper and the tape cut into 15 cm long pieces. The
silicone paper from the more strongly adhering side of Tape 1 is
removed and the nonwoven fabric is glued onto tape 1 on the side
not to be tested. Note during the testing of the nonwoven fabric,
that the nonwoven fabric has two sides: a smooth and an
consolidated side. Hence different abrasion values can be
determined for the same nonwoven fabric, depending on the side
tested. Once the samples have been prepared, the nonwoven fabric
thus prepared must be rolled over twice with the 2 kg hand roller.
No additional force is exerted here. The sample thus prepared is
next punched out to size 4 cm.times.11 cm, using the dinking
die.
[0013] The test is performed in the following steps:
[0014] The Sutherland Inc. Rubb Tester is set to 20 test cycles,
selecting velocity step 1 on the instrument. This corresponds to 42
cycles per minute. Next a 20 cm long piece of sandpaper is cut. The
sandpaper is attached to the AGS of the Sutherland Inc. Rubb
Tester, in such a way that the sandpaper no longer moves. Note that
a new piece of sandpaper must be used for each test. Next the
removable paper is peeled off the second side of tape 1 and the
composite of tape 1 and the nonwoven fabric is glued onto the metal
sheet provided for that purpose. The composite must be glued
precisely in the marked area on the metal sheet. The nonwoven
fabric is then rolled over twice with the 2 kg hand roller. No
additional force is to be applied. The weight of the metal sheet
and the tape 1/nonwoven fabric composite is then determined on an
analytical balance to four decimal places, and recorded (G1). The
AGS is then hung into the mounting support on the Sutherland Inc.
Rubb Tester. Care must be taken here that the surface of the
nonwoven fabric to be tested is not damaged and no unnecessary
pressure is applied to it. Once the measurement has been performed,
the AGS is carefully removed. Then a 20 cm long strip of tape 2 is
cut and placed loosely on the specimen. Care must be taken that the
adhesive side of tape 2 is not touched with bare hands. Next pass
the 2 kg hand roller once over the glued-on tape 2. No additional
force is applied here. Next tape 2 is pulled off the surface of the
nonwoven fabric specimen. The nonwoven fabric is weighed precisely
with the sample holder, to .+-.0.0001 g accuracy. The weight so
determined is recorded as "overall nonwoven fabric weight"
(G2).
[0015] Abrasion is calculated as follows:
Abrasion [mg/cm.sup.2]=[1000.times.(G1-G2)]/44
[0016] During evaluation, take into account that the results will
differ depending on whether the smooth or the consolidated side of
the nonwoven fabric is examined. Differences can also arise if the
sample is tested once in MD and another time in CD orientation. To
obtain uniform measurement results, care must be taken that the
test conditions are uniform. In multiple determinations of an
abrasion value, the mean value and the standard deviation are
calculated. In addition, the minimum and the maximum values are
recorded. The measurement precision of the calculated abrasion is
reported to three decimal places.
[0017] Preferably the nonwoven fabric shows an abrasion of less
than 0.3 mg/cm.sup.2 on the consolidated side. According to another
implementation the difference in abrasion between the consolidated
and the smooth side is less than 70%. It is in particular preferred
that abrasion of the consolidated side amounts to at most 50%, in
particular less than 30%, of the abrasion on the smooth side of the
nonwoven fabric.
[0018] In particular, the consolidated surface of the nonwoven
fabric can serve as outer layer of a product, compared to the
smooth side. The reduced abrasion tendency of the material makes it
possible to use the nonwoven fabric in particular in applications
in which a pronounced tendency to lint formation could lead to
undesirable side effects.
[0019] In accordance with an additional concept of the invention,
which in particular can be realized independently of the concepts
above, a nonwoven fabric is made available, with fibers that have
polyethylene on their surface, whereby the nonwoven material
exhibits a dynamic coefficient of friction (COF: coefficient of
friction) of 0.19-0.5. Preferably the dynamic coefficient of
friction will be of 0.25-0.35. If the nonwoven fabric has a
coefficient of friction in this range, then it can be successfully
used wherever it is important to use the nonwoven fabric without a
high abrasion effect.
[0020] The dynamic coefficient of friction CoF is determined using
a measurement principle in which a sled is covered with a nonwoven
fabric sample and then pulled in a defined manner over a level area
also covered with the same nonwoven fabric. The intervening forces
are recorded by a tensile tester. The standard to be consulted here
is TEFO method 18-66. The dynamic coefficient of friction is here
defined as follows:
.mu..sub.D=F.sub.mittel/(W*9.81)[(kg*m*sec.sup.2)/(kg*m*sec.sup.2)]
The dynamic coefficient of friction is thus dimensionless. The
F.sub.mittel used is the mean force in Newton obtained by the
measurement. The value W indicates the weight of the nonwoven
fabric specimen W.sub.Vlies wrapped around the sled, added to the
weight of the sled W.sub.Schlitten. The weight of the sled is 195.3
g. In addition, the concept "friction body" is defined as "sled
with attached nonwoven fabric sample" and the concept "friction
table" is defined as "platform with applied nonwoven fabric".
[0021] A tensile tester--for instance a Zwick 2.5--is required to
perform the test method, as well as a sled with a nylon thread and
an adapter for the test machine, a platform with a turn pulley and
a balance. The specimen to be tested is prepared as follows: a
nonwoven fabric specimen 1 is cut to size 65.times.100 mm and a
second nonwoven fabric 2, to size 140.times.285 mm. Care must be
taken here that the long sides are cut either in MD or CD
alignment. While carrying out the test method, the platform is
attached to the tensile tester. A 100 N load cell is installed in
the tensile tester. Next the nonwoven fabric specimen 1 is weighed
to 0.001 g precision and the weight W.sub.Viles is recorded. Then
the nonwoven fabric specimen 1 is cut centrally on one of the
narrow sides, to a depth of 3 cm and attached to the sled using
adhesive tape. Care must be taken that the adhesive tape is not on
the friction side of the nonwoven fabric specimen. Furthermore,
care must be taken that the orientation of the nonwoven fabric is
observed, i.e., its smooth or its consolidated side are indicated.
In a subsequent evaluation, care must be taken to indicate which
side was used in the test.
[0022] The nonwoven fabric specimen 2 is attached to the platform
using a double-sided adhesive tape. Care must be taken here too
that the adhesive tape is not in the friction area of the nonwoven
fabric specimen. The nonwoven fabric specimen must lie wrinkle-free
on the platform, with the longer side parallel to the longer side
of the platform. Here too, in the subsequent evaluation care must
be taken to know what orientation--smooth or consolidated side--the
nonwoven fabric presented. After the tensile tester has been
zeroed, the friction body is placed on the platform. The nylon cord
connected to the friction body is guided over the turn pulley and
connected to the tensile tester. The nylon cord is sufficiently
taut if the tensile tester shows a force of 0.03 N. Next the load
cell of the tensile tester is zeroed again. The measurement at the
tensile tester can then begin and the friction body can slide over
the friction table. The mean force F.sub.mittel and the coefficient
of friction are determined for each specimen. The force measured is
determined to a precision of 0.01 N, with the calculated dynamic
coefficient of friction being indicated with two decimal
places.
[0023] In accordance with another concept of the invention that
combines with the concepts above, but can also be further pursued
independently, a nonwoven fabric is provided with fibers that have
polyethylene at least on their surface, where the nonwoven fabric
has a bending stiffness in MD direction in the range of 0.03-0.23
mN/cm and in CD direction in the range of 0.01-0.15 mN/cm. The
softness of the nonwoven fabric can for instance be influenced via
the bending stiffness. It has proven to be advantageous for the
nonwoven fabric to have a minimum and a maximum bending stiffness,
since for instance in the use of the nonwoven fabric in contour
matching, as in medical and hygiene articles, too stiff a material
would be undesirable.
[0024] One further development provides for the nonwoven fabric to
have fibers with a titer below 3 dtex, in particular below 2.8
dtex. This is an additional way to influence abrasion. In addition,
another property, such as permeability for liquids and/or gases,
can be affected hereby.
[0025] The nonwoven fabric preferably has a tensile force at
maximum peak in CD direction of at least 3 N, preferably of at
least 8 N, in particular 12 N, and in MD direction of at least 5 N,
in particular of at least 10 N, preferably of at least 15 N. In
particular, the nonwoven fabric has a tensile force in CD direction
at least 20 N high and in MD direction at least 25 N high. The
tensile force is here determined following DIN/EN 29073-3, June
1992 version. However, the following deviation is adopted in the
determination: the distance between the clamps is 100 mm, instead
of 200 mm, as the standard states. The velocity at which a
cross-head of the measurement machine is moved is of 200 mm/min,
instead of 100 mm/min as defined in the standard. The specimen size
is 50 mm in width and 200 mm in length. When the specimen is
clamped in, care must be taken that the tension acting on the
nonwoven fabric lies between 0 and 0.5N. The test is performed
until the specimen tears. From the force-elongation curve so
determined it is possible to determine the maximum tensile force at
maximum peak and therewith the elongation at maximum force in %,
the elongation at 5 N and at 10 N in % and the tensile force at 5%
elongation, in Newton. The tensile force is determined with a
precision of 0.1 N and the elongation with a precision of 0.1%.
[0026] According to one implementation, the nonwoven fabric
exhibits a grammage of 13-30 gsm. According to another
implementation, the grammage has a value of 15-20 gsm. With an
appropriate embossing, at such a grammage sufficient tear forces
can be made available for applications in particular in the hygiene
area.
[0027] Another implementation provides for a nonwoven fabric with
softness that is preferably greater than 2.1. A softness value
greater than 3.1 is particularly desired.
[0028] One implementation provides for at least part of the fibers,
preferably all fibers, to have a core-sheath structure. This
core-sheath structure is preferably caused by different polymers.
The casing can for instance be polyethylene, while the core has
polypropylene. In particular, polymer mixtures can also be used
here, with a core of different composition than the polymer
composition of the casing. Also different polyethylene for the core
and for the casing can be used. Another implementation provides for
the core-sheath structure to include a light oxidation surface. In
particular this oxidation surface can exist additionally. By means
of an oxidation surface it is possible to improve the bonding
properties in a subsequent thermal bonding step. Preferably a
polypropylene has an oxidation layer on its surface.
[0029] Furthermore, the core-sheath structure can be such that for
instance a multi-component material is present, in particular a
two-component material, where the casing is not arranged
homogeneously but inhomogeneously around the core. The arrangement
can for instance be in the form of thickenings and thickness
reductions. In accordance with another implementation, the casing
arrangement can even be partially discontinuous, so that the core
appears in at least some segments.
[0030] Besides a core-sheath structure in the form of a
two-component fiber, the core-sheath structure can also be
eccentric. Segment fibers can also be formed.
[0031] A further implementation provides for at least part of the
fibers to have a non-circular cross-section. In particular the
fiber cross-section can be oval, flattened, trilobal or in any form
that increases the surface. Besides an especially large surface
area, in this manner a deposit on the fiber surface can achieve
better adherence, because of the enlarged surface. The fiber can
preferably have a star-shaped cross-section, where a gusset is
formed between two radially outward stretching segments. An active
substance can for instance be placed in this gusset.
[0032] The fiber can be at least either partially or completely
equipped with an additional covering. This covering can be applied
on the entire surface of the nonwoven fabric. To this end, for
instance foam depositions, spray depositions, wetting procedures,
vapor deposition procedures, ionization procedures and/or immersion
bath procedures, as well as other possibilities, can be used. The
covering can be applied off-line or on-line.
[0033] In accordance with another implementation form, at least a
part of the nonwoven fabric fibers, preferably all of them, can
have a hollow core. In this manner it is on the one hand possible
to achieve a weight reduction, while on the other the hollow core
can be used to achieve certain properties. A hollow core can for
instance make available an improved liquid uptake. The hollow core
can also contain an active agent that is gradually released to the
outside. A further development provides for at least a part of the
fibers, in particular all fibers of the nonwoven fabric, to be
curled. A curl can for instance be achieved by means of special
heat treatments, making use of different polymers contained in a
nonwoven fabric fiber. Curling can also be achieved by stretching
the nonwoven fabric or respectively, its fibers. Preferably the
curling is accomplished by means of a process step before, during
and/or after a consolidation process, in particular a thermal
bonding process to bond the nonwoven fabric fibers to each other.
Another implementation provides for the nonwoven fabric to be a
thermally bonded spunbonded nonwoven fabric. Another implementation
provides for the nonwoven fabric to be a carded nonwoven
fabric.
[0034] In accordance with another concept of the invention, a
device is proposed for the manufacture of a nonwoven fabric using a
polyethylene-containing polymer, with a take-down mechanism that
causes the take-down of the polyethylene beneath a spinning plate,
where the spinning plate has an L/D ratio of 4-9. Here the value of
L refers to the length of spinning plate boring through which the
polymer flows to form a thread upon exiting. The value D in turn
indicates the diameter of the spinning plate boring. The boring can
be manufactured by different processes.
[0035] Another implementation provides for the L/D ratio to be
between 6 and 8. Yet another implementation provides for the L/D
ratio to be between 4 and 6. Preferably, the L/D ratio is in
between 4.5 and 9, especially between 5.5 and 7.5. In particular,
the possibility exists of achieving a high spinning throughput by
adapting a MFI value to the L/D ratio. In accordance with a further
implementation the spinning plate temperature--and according to a
continued development, also the polymer temperature before it
passes through the spinning plate--is coordinated with the L/D
ratio, in conjunction with the polymer material.
[0036] In addition, the spinning plate can have different
configurations. For instance, the diameter D can be uniform over at
least most of the length L. Here, "uniform" can mean constant, but
also evenly increasing or decreasing. The diameter D can also have
a narrowing in its initial range, while being nearly constant in
the remaining portion. In turn, the length L is preferably such
that it represents the shortest distance from one side of the
spinning plate to the opposite side. In accordance with a different
configuration, at least part of the spinning plate holes are not at
right angles to at least the side of the spinning plate on which
they open.
[0037] Another configuration provides for the neighboring holes in
the spinning plate to be arranged in rows parallel to each other
along one width and one length of the spinning plate.
[0038] Another implementation provides for neighboring holes in the
spinning plate to be offset with respect to each other. This makes
it possible for the polymer threads exiting the spinning plate
borings to be exposed to a quenching agent to cool them and so that
they can be stretched. In particular, the spinning plate geometry
and the geometry of spinning plate boring arranged on it can be
coordinated with the flow velocity of the quenching agent.
[0039] Preferably it is provided an enclosure for a take-down
device for the polyethylene and the spinning plate. In particular
it is provided for such an enclosure to be penetrable, at least in
the area of the take-down mechanism. A further development provides
for the enclosure to extend at least in part in the direction of a
deposition device for the polymer threads. This makes it possible
to purposefully reduce environmental influences due to the
conditions surrounding the device, and thereby intentionally
adjusting the temperature conditioning of the take-down of the
polymer threads and thereby, cooling and stretching.
[0040] Another implementation provides for the device to have an
enclosure, as housing. The enclosure preferably is under a pressure
of 10-50 mbar. This allows achieving a particularly good stretching
of the polymer threads. Yet another implementation provides that at
least a one-sided quenching air flow be arranged beneath the
spinning plate. Furthermore, a two-sided quenching flow can also be
provided. The quenching air can here flow perpendicularly and/or at
an angle onto the polymer threads. In particular, the quenching air
can be temperature conditioned. This means that at least its
temperature, but for instance also its moisture content, its
velocity and hence its pressure and the volume flow, and/or other
parameters, can be intentionally adjusted.
[0041] One further development provides a split quenching to be
arranged underneath the spinning plate. Here, in a first step
underneath the spinning plate, a first quench airflow quenches the
polymer threads and stretches them. It can also be provided for an
optimization of the stretching during the first quenching by
heating the quenching air, so that the fiber is not cooled too fast
and hence can be stretched longer. A subsequent quenching has a
differently conditioned quench air, compared to the first. This
conditioning is adapted to the prestretched and cooled state of the
polymer threads existing at that point. The conditioning can
provide for the second quenching to have a higher temperature,
higher volume flow, higher flow, higher velocity and/or a different
flow direction than the first quenching. According to another
implementation, the second quenching has lower conditioning
parameters than the first. Hence, the device preferably has at
least two areas, in the zone beneath the spinning plate and to a
deposition device, in particular a screen belt, in which different
take-down parameters can be set. A quench differing in many ways
can also be used for this purpose.
[0042] Another implementation provides for the device to be such
that the take-down velocity can be adjusted in a range of 900-6000
m/min. In this manner, different procedure parameters, and polymer
threads as well as polymer compositions can be processed into a
nonwoven fabric. For instance, one or several compactors can be
provided those are able to realize different take-down velocities.
A nozzle system can also be provided to select different take-down
velocities. For instance, a nozzle geometry can here be adjustably
modified. A take-down velocity can also be set via different
tempering and pressure settings of a quenching air. This can in
particular be realized in conjunction with a changeable or
different nozzle geometry. One further development for instance
provides for the depressurizing of a pressurized quenching air.
Depressurization can be achieved in different ways, so that
different take-down velocities can thereby be set.
[0043] Another further development of the device provides for a
nozzle arrangement for the flow-through of polymer threads from the
spinning plate to be placed under the spinning plate, which first
has a constriction, then an averaged diameter and finally, an
enlargement. The nozzle arrangement can here be in one or several
pieces. The nozzle arrangement can also be subdivided. Preferably
the nozzle arrangement is penetrable, i.e., it allows screening the
polymer threads from the device's immediate surroundings.
Preferably the nozzle arrangement is such that the polymer threads
enter in contact with the immediate surroundings of the device only
immediately before they are deposited, for instance on a screen
belt. Before that the polymer threads are only under a conditioned
state, determined by the quenching air and/or other media supplied
to the nozzle arrangement.
[0044] It has furthermore proven to be advantageous for the
spinning plate to have at least 4500 holes/m, in particular more
than 6000 holes/m and preferably, more than 7000 holes/m. Another
implementation provides for the spinning plate to have a hole
density of 4.5-6.3 holes/cm.sup.2. The spinning holes in the
spinning plate can hereby have a taper. In this manner it is
possible to achieve a nozzle effect and in particular, an
acceleration of the polymer material inside the spinning plate.
This makes it possible to spin the polymer material into thin
polymer threads.
[0045] Preferably it is preferably for the borings in the spinning
plate for the flow-through of the polymer to have a diameter larger
than 0.4 mm. Such a size makes it possible, on the one hand, to
achieve a high throughput of polymer through the spinning plate,
while on the other hand with such a size sufficiently fine nonwoven
fabric threads can be obtained, preferably of less than 3 dtex, in
particular of less than 2.8 dtex. The boring diameter of at least
0.4 mm also makes possible with the polyethylene-containing
material to achieve throughputs higher than 100 kg/h/m and
especially higher than 120 kg/h/m, in particular of more than 150
kg/h/m and preferably, of higher than 180 kg/h/m. In particular,
throughputs of polyethylene-containing polymer material can be
attained that exceed 200 kg/h/m and that make possible a nonwoven
fabric with a titer of less than 3 and an abrasion of less than 0.4
mg/cm.sup.3 at an consolidated area fraction of less than 30%,
preferably less than 25%, especially less than 20%. Preferably here
the borings in the spinning plate have a diameter in the range of
0.4-0.7 mm, preferably up to 0.9 mm. Preferably the boring diameter
is of 0.6-0.9 mm. With a spunbond nonwoven fabric line throughputs
in the range of 220-240 kg/h/m can be achieved.
[0046] An improvement in the spinning of polyethylene-containing
polymer material can be achieved by a coating on the spinning
plate. The coating can for instance be chromium plating. However,
it can also be a PTFE treatment. Other coatings that in particular
reduce adherence of polymer material, but do not impede heat
passage, can also be used.
[0047] A further implementation provides for the device to include
a heatable calender that is connected to the device. The calender
preferably has at least a smooth-surfaced roller and an engraved
roller. In accordance with a first implementation the
smooth-surfaced roller and the engraved roller are heated to
different extents. Preferably the smooth-surfaced roller is at a
lower temperature than the engraved roller. Thermal bonding of the
nonwoven fabric material is performed with the heatable calender,
to set the consolidated area fraction to preferably less than 23%
and in particular, to less than 20%, in particular in a range of
13-18%. Preferably it is planned that achieving the embossing after
the deposition of the nonwoven fabric fibers be accomplished in a
single step, in particular just by means of a heatable calender. In
this implementation there is no further consolidation of the
nonwoven fabric material.
[0048] The thermal bonding step can be additionally furthered by
means of a coating on at least one of the calender rollers.
Preferably the coating is such that adhesion is avoided, in
particular adhesion of the polymer material heated in the thermal
bonding step. One calender roller can for instance have a PTFE
coating.
[0049] Heating of the calender rollers is preferably accomplished
by means of internal heating, for instance ensured by a liquid
circulation. A calender roller can also be heated by means of
gaseous media. Preferably different heating circuits are provided,
so that different heating is possible in two opposing calender
rollers. Preferably a temperature difference of at least 2.degree.
C. can be set, in particular a temperature difference of up to
10.degree. C. It is also possible to heat both calender rollers to
the same temperature.
[0050] Another implementation provides that the device include an
arrangement that allows the manufacture of a core-sheath structure.
To this end, the device preferably has a spinning plate for the
generation of a core-sheath structure, in which the device
generates the casing with a polyethylene-containing polymer and the
core with a polypropylene-containing polymer. The spinning plate
and all the remaining components of the device are adjusted for the
procedural parameters necessary in each case for the different
polymers. This for instance means that different temperatures,
different line diameters and different polymer extruders can be
made available.
[0051] According to another concept of the invention, a procedure
is made available for the manufacture of a nonwoven fabric the
fibers of which have polyethylene on the surface at least in parts,
whereby the fibers can be further processed after take-off at a
velocity of at least 650 m/min, in particular 1500 m/min from a
spinning plate, where the polymer is heated in an extruder to
between 200.degree. C. and 250.degree. C. and passed at that
temperature through a spinning plate heated to between 190.degree.
C. and 240.degree. C., where the polymer is divided into individual
polymer threads in a spinning plate with a least over 4500 holes/m,
where the polymer threads in each case flow through the spinning
plate along a path that is at least four times as long as a polymer
thread diameter. The polymer thread diameter used here is the
diameter at the exit from the spinning plate.
[0052] Preferably it is provided for the polymer threads to be
stretched at a take-off velocity of 3000-4500 m/min.
[0053] The polyethylene is preferably mixed as dry blend with
another polymer before going into the extruder. This has shown
particularly advantageous effects during processing, since thereby
the throughput can be increased to over 160 kg/h/m.
[0054] One further development provides for the polymer thread to
be deposited on a screen belt, to be subsequently compacted by
means of a calender, the rollers of which are heated to different
degrees. Consolidation occurs in a thermal bonding step. It is
preferably provided for the polymer threads to be thermally bonded
in a temperature range of 112-135.degree. C., with a consolidated
area fraction of less than 30%, preferably less than 28%,
especially less than 23%. In particular, a nip pressure in the
calender amounts to 40-80N/mm, particularly to only 40-60 N/mm.
[0055] In accordance with one implementation, a polyethylene being
a homo- or a copolymer is bonded in a temperature range that can
reach up to 140.degree. C. In another implementation a Bico
material is bonded in a temperature range than can reach up to
155.degree. C.
[0056] The nonwoven fabric can be used to particular advantage in
an application in which it is used on the outside of a product, as
covering.
[0057] The polymer material used for the fibers can be a
polyethylene by itself, or in a blend. A blend can be obtained
either by compounding or by dry-blending of one or several
polymers. In particular, the concept "polymer" includes
homopolymers, copolymers and inter-polymers, i.e., polymers formed
by polymerization of at least two different kinds of monomers. This
means that the polymer material can be a copolymer, a terpolymers,
etc. The polyethylene polymer can for instance be a LDPE, a LLDPE
and/or a HDPE. They can be formed by homopolymerization of
ethylene, or by inter-polymerization, for instance copolymerization
of ethylene with one or several vinyl or diene-based comonomers. An
.alpha.-polyolefin with three to twenty carbon atoms can for
instance be used, or a vinyl ester, or a styrene-based monomer, as
well as other copolymerization reactions.
[0058] The polyethylene that can be used can for instance be of
homogeneous or inhomogeneous linkage of the molecules. In addition
to using long-chain, essentially linear polyethylene, short-chain
polyethylene polymers can also be used. Furthermore, both LLDPE and
HDPE can be used. The polyethylene preferably has a bimodal
molecular weight distribution, but the polymer or copolymer,
respectively, can also have a unimodal molecular weight
distribution. A polyethylene with octene, in particular a
metallocene-LLDPE with octene is preferred.
[0059] It was surprisingly found that polyethylene-containing
material can be used by itself or in mixtures with other polymer
material in the manufacture of nonwoven fabric fibers which was
used to date only in the injection molding area, especially for
roto-molding, for sheets or other plastic processing areas, but not
in the nonwoven fabric area.
[0060] A polymer material can for instance include a polyethylene
blend by itself, or as a partial constituent, as described in US
2003/0149180. It is also possible to use homo and copolymers and
polymer blends, for instance with polypropylene, as described in EP
260 974 A1, for example. Regarding the polymers necessary to
manufacture nonwoven fabric fibers, their manufacture and
composition, in the framework of this invention it is referred to
these two documents, the content of which are part of the
disclosure in this description.
[0061] It is furthermore possible to use polymer blends and
polymers, in particular admixed, as known for instance from US
2002/0144384, from US 2001/0051267, from US 2002/0132923 and from
US 2002/0019490. The relevant content of these documents is also
part of this description, within the framework of the
disclosure.
[0062] An essentially linear polyethylene can for instance be
manufactured in a continuous process, with at least one reactor.
Something of this type is for instance described in WO 93/07187, WO
93/07188 and WO 94/07189, the content of which is part of the
description, within the framework of this disclosure. A multiple
reactor arrangement can also be used, for instance as described in
U.S. Pat. No. 3,914,342. The disclosure made there is hereby also
included in this description.
[0063] The polyethylene can for instance be manufactured using a
Ziegler-Natta, or a Kaminsky-Sinn polymerization reaction. In
addition, the polyethylene can be manufactured by a metallocene
process. The possibility furthermore exists of manufacturing
polymer mixtures by manufacturing each fraction of the mixture
separately and combining them only subsequently. This has the
advantage of particularly variable regulation possibilities, by
changing the individual fractions. Another possibility provides for
a reactor to be adjusted for a desired polyethylene-containing
polymer, to be then operated continuously at this ratio.
[0064] In accordance with a first implementation, preferably a
LLDPE is used that has a density preferably in the range of
0.9-0.955 g/cm.sup.3. According to a different implementation, a
ULDPE or a VLDPE can for instance be used, with densities in the
range of 0.87-0.91 g/cm.sup.3, approximately. Or a HDPE with a
density of for instance 0.941-0.965 g/cm.sup.3 can be used. Also PE
materials with different densities mixed together can be used.
[0065] According to another implementation, a polyethylene material
is used in which the M.sub.W/M.sub.N range lies for instance
between 2 and 4, in particular between 2.6 and 3.2. The material
preferably has a molecular weight in the range of 40,000-55,000
g/mol, in particular of 46,000-52,000 g/mol. The density is
preferably adjusted to 0.85-0.955 g/cm.sup.3. The MFI preferably
lies in the range of 10-30 g/10 min at 190.degree. C./2.16 kg. It
is in particular also possible to mix two or more polymers, for
instance as dry blend or as compound. This material comprises
preferably the same parameters as mentioned above. According to one
implementation, at least one polyethylene-containing polymer has a
high MFI, for instance of 30 g/10 min at 190.degree. C./2.16 kg,
with a high density, and the second polyethylene has a lower MFI,
for instance of 10, and a lower density than the first one. The
polymers are preferably unimodal. Another implementation provides
for the use of a polyethylene-containing polymer with a density of
0.955 g/cm.sup.3 and an MFI of 29 g/10 min at 190.degree. C./2.16
kg. Another implementation comprises or consists of at least a PE
polymer that has a bimodal molecular weight distribution.
[0066] In addition to polyethylene, at least one other
thermoplastic material can be mixed with the polyethylene material,
or arranged next to it. The thermoplastic material can for instance
be a polyolefin such as polypropylene, or a polylactitol, an
alkenyl-aromatic polymer, a thermoplastic polyurethane, a
polycarbonate, a polyamide, a polyether, a polyvinyl chloride
and/or a polyester, or other polymer materials such as block
polymers and elastomers. This listing is not intended to be
limiting.
[0067] In addition, a nonwoven fabric fiber can include other
material fractions, for instance additives. They can be added as
master batch and/or during compounding. Antioxidants and/or other
additives can for instance be used. A property of the nonwoven
fabric may thereby be influenced, or also by treating the nonwoven
fabric with a fluid, for instance by coating, spraying, diffusion,
etc.
[0068] Examples of possible additives are flame retarding
additives. The possibility also exists of stabilizing the nonwoven
fabric with respect to solar and other radiation, for instance
heat, beta and/or gamma rays. To this end thermal and/or UV
stabilizers can be used as additives (for instance HALS, hindered
amine light stabilizer). There is also the possibility of using
opalescent pigments, for instance. Colored additives can also be
used, for instance in the form of pigments. The possibility also
exists of using clarifying agents as additives, and/or nucleating
additives, optical brighteners, fragrances such as perfumes,
aromatic additives such as spices like vanilla, hydrophilizing
agents, hydrophobing agents, fillers, titanium dioxide, and
antistatic agents.
[0069] Furthermore, it is possible to use additives or coatings
with antimicrobial effects, such as biostatic or biocidal
additives, depending on the desired use of the invention. Some
examples of substances with antimicrobial activity are Irgaguard B
1000 from Ciba Specialty Chemicals, or numerous commercially
available products that contain silver ions (for instance AlphaSan
RC 5000 from Milliken Chemical). Odor-controlling additives such as
zeolites can also be added.
[0070] According to one implementation a polyethylene is for
instance used that has a MFI of 15 g/10 min at 190.degree. C./2.16
kg, measured following ISO 1133. The material has a density of
0.935 according to ISO 1183 and a melting point of 127.degree. C.
The Vicat softening temperature is 111.degree. C. as measured by
ISO 306 (Method A120). The crystallization temperature is
107.degree. C. as measured by DSC. This polyethylene can be spun as
homopolymer, or in combination with another polymer material. An
additional polyethylene material that can be spun by itself or in a
mixture, has a MFI of 27 g/10 min at 190.degree. C./2.16 kg
according to ISO 1133. The density is 0.941 gcm.sup.3 according to
ASTM D-792. The DSC melting temperature is 126.degree. C. Another
polyethylene material that can be spun has a MFI of 30 g/10 min at
190.degree. C./2.16 kg, according to ISO 1133. The density is 0.955
g/cm.sup.3 per ASTM D-792. The DSC melting temperature is
132.degree. C. These polymers mentioned as examples were spun in
some cases as homopolymers and in others as polymer mixtures with
other thermoplastic materials, especially with those mentioned.
Preferably these and others have molecular weights in the range of
20,000-70,000 g/mol, preferably in a range of 40,000-70,000 g/mol.
The polymers can in particular also be processed in the temperature
range of 190-240.degree. C. Below other advantageous polymer
materials are discussed in greater detail.
[0071] It has for instance proven to be positive to mix different
polyethylene materials with each other. This can be realized as a
dry blend, but also in an appropriate compounding. Advantageously
this polyethylene has a different density and a different MFI than
the at least second polyethylene material. It is particularly
advantageous if the MFI of the material to be spun is >20.
[0072] It can furthermore be provided for various polyethylene
materials to be mixed together and then adding one or more
additional polymers. Two or more polyethylene materials can for
instance be in a mixing ratio in a band width of 80:20 to 20:80. To
this material a polypropylene can for instance be added. The
polypropylene can for instance be isotactic, or also syndiotactic
or atactic. It was shown to be particularly advantageous for the
MFI of the material to be spun to be >25, in particular in the
range of 28-35 g/10 min according to ASTM D-1238. It was also found
to be particularly advantageous for the density of the material to
be spun to be in the range of 0.935-0.975 g/cm.sup.3.
[0073] It was furthermore shown to be advantageous to seek a MFI
value >20 for the material to be spun, preferably a MFI value
between 20 and 30. In this manner it becomes possible to set a
spinning temperature in a range of for instance 19-225.degree. C.
In particular it thereby becomes possible to set the nip pressure
in the downstream calender in a very low range. Preferably the
calender nip pressure had a value in the range of 40-70 N/mm, in
particular of 40-60 N/mm, at the same time achieving a stable
embossing result. In particular, this makes possible a durable
process able to run for several hours at constant fiber or nonwoven
fabric results. It has also proven advantageous for the calender to
have a roughness R.sub.z of approximately 35-50 .mu.m, in
particular of 40 .mu.m. However, the surface roughness can also be
higher or lower. If a coating is applied, for instance, it
advantageously has a layer thickness of 100-200 .mu.m. A polymer
coating can for instance be provided for.
[0074] It has furthermore been shown to be advantageous for the
polymer material used to have a width of molecular weight
distribution M.sub.W/M.sub.N of 2-3.5. It has also proven to be
advantageous to add a master batch containing a stabilizer, for
some polyethylenes or polyethylene-containing mixtures. The
fraction of the master batch can here for instance be of up to 5
wt.-% of the material to be spun. It was preferably established in
some tests that an addition of master batch in the range of 0.1-1.5
wt.-%, with the correspondingly lower stabilizer fraction, was
sufficient.
[0075] A fluoro-elastomer can furthermore for instance be added to
the polyethylene or the polyethylene copolymer. The
fluoro-elastomer contributes to avoid cracking of the spinning
plate. Another implementation provides for a lubricant to be added
to the polymer material. The lubricant can here be added in a dry
blend, or during compounding. The lubricant added can for instances
be an internal, or also an external lubricant. The lubricant
accomplishes a further reduction in the fiber's titer. Examples of
lubricants that can be used are for instance fatty acids, for
instance monoamido-fatty acids, carbonated fatty acids and fatty
acid mixtures. It is furthermore possible to use polyethylene wax,
montan wax and wax emulsions. Hydrocarbon wax in particular has
proven advantageous as an internal lubricant.
[0076] In accordance with a further implementation, a polyethylene
material is used that has an MFI value of 15-20 g/10 min at
190.degree. C./2.16 kg for the material to be spun. This makes it
possible to set a temperature at the spinning plate that is in the
range for instance of 190-250.degree. C. In particular, it also
makes possible setting a nip pressure in the calender downstream
that is very low. The calender nip pressure can preferably have a
value of 40-60 N/mm.
[0077] An extruder temperature profile can furthermore be built in
such a way that the temperature is higher in the inlet area than in
the outlet area. The temperature profile can also be such that the
temperature in the inlet area is lower than that in the outlet
area. In addition, varying the extruder length, the temperature can
for instance first increase and then decrease again.
[0078] Below some examples of experimental setups and experimental
results are reported. However, they should not be considered
limiting and are merely an extract of the tests performed.
[0079] Below, for instance, is described the configuration used to
perform some of the spinning tests for the manufacture of
two-component fibers. The tests were performed on a Reifenhauser
III beam. Two separate extruders and spinning pump systems were
used. The first extruder has a screw of 150 mm diameter with
different screen packs of order of magnitude 60, 180 and 250 mesh
(0.16, 0.05 and 0.04 mm). The second extruder has a screw of 80 mm
diameter and screen packs of order of magnitude 50 and 120 mesh
(0.2 and 0.08 mm). A spinning package with a spinning plate with
5.297 holes (4.414 holes per m) was used. Each hole had a diameter
of 0.6 mm and an L/D ratio of 4. The calender had a smooth-faced
roller and an engraved roller, both of which were heated. The
engraved roller had an oval embossing pattern, where the fraction
of embossing area was 16.19%. The land area points were
0.83.times.0.5 mm with a depth of 0.84 mm. The temperature of each
roller could be regulated separately. The nip pressure in the
calender could also be adjusted. In addition, different
consolidating patterns were used in this as in other calenders in
other tests. Elliptical, round, diamond-shaped, rod-shaped and
U-shaped patterns were used, with consolidated area fractions of
14.5-35%.
[0080] The extruder was for instance adjusted as follows:
[0081] The first extruder had an outlet temperature of
210-228.degree. C. at the extruder head. The second extruder was
operated in a temperature range of 210-230.degree. C. at the
extruder head. The temperature of the second extruder could here
differ from that of the first extruder. The temperature difference
used for the extruder head was for instance of 5-15.degree. C. Good
results were also obtained with Bico materials when the exit
temperatures were the same.
[0082] The temperature of the spinning block was set to
220-240.degree. C. The pressure applied to the spinning block was
of 30-50 bar, but it can also be in the range of 70-100 bar. The
cabin pressure was varied between 13 and 20 mbar. The quenching was
performed at a temperature between 16.5 and 24.degree. C. However,
these parameters are only indicated as examples. The cabin pressure
for example can have values of up to 50 mbar and beyond. The
quenching temperature can also be above or below the range
indicated.
[0083] Other tests were for instance performed on a Fourne line.
The spinning plate used had 162 holes of capillary borings with 1.4
mm diameter each. Here the melt temperature and the spin plate
temperature were varied, with especially good results obtained in
the range of 205-220.degree. C. Also used for instance was a spin
pack equipped with a spinning plate with 105 holes and a capillary
diameter of 0.6 mm. The L/D ratio was 8.
[0084] Furthermore, the first and the second extruder were also
used in the manufacture of nonwoven materials of a single material.
This means that a homogeneous material was used. It was possible
here to use both extruders simultaneously, or just one of them.
When both extruders were used simultaneously, their parameters and
in particular, their temperature profiles, were set at least
approximately equal. Here the parameters could vary in the same
ranges indicated above for the first extruder on the one hand, and
for the second on the other.
[0085] A Lurgi-Docan line was for instance also used to perform
these tests. For instance, a spinning package with 2.268 holes/m in
the spinning plate was used. Temperatures between 175.degree. C.
and 269.degree. C. were set.
[0086] Below some of the experimental results are shown. The test
results are merely examples and should not be viewed as
limiting.
Compilation of Test Results with a PE/PP Bico Material
TABLE-US-00001 [0087] Versuch 324 331 352 Polymer PP1/PP1 als PP1/
PP1/PE1 Vergleichsmaterial PE1 (50/50) Basisgewicht [gsm] 17 27 20
Kalandertemperatur [.degree. C.] 155 125 135 F [N] MD
Rei.beta.festigkeit 43.2 44.74 38.41 std. [N] 4.93 5.90 3.73 F [N]
CD Rei.beta.festigkeit 28.50 25.03 21.89 std. [N] 2.28 2.37 1.82
Elongation @ Peak [%] MD 70.70 57.72 65.60 std. [%] 9.04 12.09 9.86
Elongation @ Peak [%] CD 72.92 76.23 71.05 std. [%] 10.69 9.72 5.91
[mN cm] MD Biegesteifigkeit 0.45 0.71 0.55 std. [mN cm] 0.14 0.15
0.15 [mN cm] CD Biegesteifigkeit 0.24 0.24 0.20 std. [mN cm] 0.09
0.08 0.05 [dtex] Titre 2.3 2.1 2.3 std. [dtex] 0.3 0.5 0.5
[mg/cm.sup.2] Fuzz 0.321 0.973 0.505 std. [mg/cm2] 0.064 0.136
0.081 [g/10 min] MFR 42 19 20 std. [g/10 min] 3 0 0 COF (MD) 0.37
0.15 0.35 std. 0.09 0.04 0.03 SPU Softness 1.20 1.80 0.90 Versuch =
test Basisgewicht = base weight Kalandertemperatur = calender
temperature Reissfestigkeit = tensile strength Biegesteifigkeit =
bending stiffness Vergleichsmaterial = reference material std. =
standard deviation PP1 = PP homopolymer with MFR of 27 according to
ISO 1133 and a density of 0.9 g/cm.sup.3 PE1 = resin A, see
below
Compilation of Test Results 1 with a Polyethylene Material
TABLE-US-00002 [0088] Versuch 397 401 404 405 421b 417 428 429 469
467 Polymer PP als PP als Ver- Ver- gleichsma- gleichs- terial
material PE1 PE1 PE2 PE2 PE3 PE3 PE4 PE4 Basisgewicht [gsm] 20 27
20 27 20 27 20 27 20 27 Kalandertempera- 145 155 130 130 135 135
125 125 130 140 tur [.degree. C.] Quenchtemperatur 22 22 22 22 22
22 22 22 22 22 [.degree. C.] Spaltdruck [N/mm] 70 70 70 70 70 70 70
70 70 70 F [N] MD Rei.beta.fe- 36.61 66.08 8.69 13.99 11.76 11.28
10.48 15.17 14.43 10.97 stigkeit std. [N] 3.12 3.42 1.13 1.05 1.12
0.56 0.50 0.99 2.30 2.61 Force [N] CD Rei.beta.- 25.63 46.45 5.70
9.37 5.85 9.54 7.22 12.21 6.37 10.30 festigkeit std. [N] 2.92 1.35
0.66 0.71 1.13 0.86 0.73 0.86 0.99 1.54 Elongation @ Peak 50.75
71.35 47.57 60.52 43.79 98.79 166.80 171.45 76.56 62.60 [%] MD std.
[%] 6.52 7.62 14.33 12.26 6.57 14.74 12.25 16.83 18.24 20.39
Elongation @ Peak 52.08 68.31 50.29 65.40 82.91 125.78 151.04
191.59 94.27 99.18 [%] CD std. [%] 7.43 3.77 9.41 10.66 16.64 15.61
25.55 15.73 20.15 21.93 [mN cm] MD Biege- 0.508 1.426 0.091 0.206
0.062 0.135 0.049 0.135 0.069 0.061 festigkeit std. [mN cm] 0.102
0.297 0.040 0.053 0.029 0.034 0.012 0.049 0.022 0.024 [mN cm] CD
Biege- 0.231 0.887 0.036 0.087 0.015 0.055 0.024 0.079 0.016 0.061
festigkeit std. [mN cm] 0.048 0.235 0.014 0.025 0.013 0.016 0.009
0.046 0.006 0.027 [dtex] Titer 1.99 2.11 2.74 2.72 2.50 2.75 2.85
2.83 2.83 2.83 std. [dtex] 0.19 0.17 0.20 0.23 0.26 0.33 0.09 0.12
0.12 0.12 [mg/cm.sup.2] Abrieb 0.605 0.216 0.386 0.790 0.459 0.265
0.559 0.640 0.538 0.437 std. [mg/cm.sup.2] 0.109 0.097 0.190 0.087
0.069 0.142 0.093 0.153 0.123 0.034 COF MD 0.290 0.309 0.307 0.271
0.415 0.318 0.374 0.370 0.366 0.315 std. COF 0.012 0.013 0.006
0.016 0.013 0.023 0.014 0.015 0.018 0.010 als Vergleichsmaterial =
as comparison material Basisgewicht = base weight
Kalandertemperatur = calender temperature Quenchtemperatur =
quenching temperature Spaltdruck = gap pressure Reissfestigkeit =
tensile strength Biegefestigkeit = bending stiffness Abrieb =
abrasion std = standard deviation PP = PP1 = PP homopolymer with
MFR of 27 (190.degree. C./2.16 kg) according to ISO 1133 and a
density of 0.9 g/cm.sup.3 according to ISO 1183 PE1 = resin A, see
below PE2 = resin D, see below PE3 = resin E, see below PE4 = resin
G, see below
Compilation of Test Results 2 with a Polyethylene Material
TABLE-US-00003 [0089] Versuch 512_3Z W 488 489 490 497 545_7d
Polymer PE5 PE5 PE5 PE5 PE5 PE5 Bonding Muster 3 zones Oval Oval
Oval Oval 70 dots Bonding Flache [%] 25 16.19 16.19 16.19 16.19
14.5 Basisgewicht [gsm] 20 20 20 20 20 20 Kalandertemperatur
[.degree. C.] 125 125 130 135 130 125 Quenchtemperatur [.degree.
C.] 22 22 22 22 22 22 Spaltdruck [N/mm] 40 40 40 40 60 50 F [N] MD
Rei.beta.festigkeit 13.41 10.53 14.23 14.67 14.84 14.62 std. [N]
0.65 4.51 1.72 1.34 1.21 0.83 F [N] CD Rei.beta.festigkeit 8.36
4.51 6.37 8.24 7.34 10.67 std. [N] 0.46 1.59 1.65 1.07 0.44 1.22
Elongation @ Peak [%] MD 112.42 41.18 70.46 72.22 77.86 105.28 std.
[%] 6.03 20.73 14.47 12.33 9.01 9.52 Elongation @ Peak [%] CD
135.27 64.46 85.64 98.76 95.88 122.49 std. [%] 12.52 17.24 19.35
14.71 8.16 13.06 [mN cm] MD Biegefestigkeit 0.022 0.049 0.047 0.067
0.062 0.045 std. [mN cm] 0.006 0.010 0.014 0.040 0.019 0.018 [mN
cm] CD Biegefestigkeit 0.011 0.017 0.020 0.018 0.019 0.015 std. [mN
cm] 0.006 0.007 0.005 0.009 0.007 0.003 [dtex] Titer 2.72 3.15 2.87
2.98 2.58 std. [dtex] 0.23 0.22 0.47 0.37 0.27 [mg/cm.sup.2] Abrieb
0.103 0.097 0.131 0.199 0.185 0.332 std. [mg/cm.sup.2] 0.059 0.029
0.076 0.097 0.107 0.184 COF MD 0.372 0.444 0.416 0.376 0.318 0.455
std. COF 0.046 0.010 0.010 0.044 0.045 0.005 Versuch = test Muster
= pattern Flache = surface area Basisgewicht = base weight
Kalandertemperatur = calender temperature Quenchtemperatur =
quenching temperature Spaltdruck = nip pressure Reissfestigkeit =
tensile force Biegefestigkeit = bending stiffness Abrieb = abrasion
std = standard deviation PE5 = metallocene LLDPE with MFR of 15
g/10 min (190.degree. C./2.16 kg) according to ISO 1133 and density
of 0.935 g/cm.sup.3 according to ISO 1183
[0090] Further examples are:
[0091] A series of fibers were used to make a series of nonwoven
fabrics. The resins were as follows: Resin A is an ethylene
homopolymer having a melt index (1.sub.2) of 30 gram/10 minutes and
a density of 0.955 g/cc. Resin B is an ethylene homopolymer having
a melt index (1.sub.2) of 27 gram/10 minutes and a density of 0.941
g/cc. Resin C is a homogeneous substantially linear
ethylene/a-olefin having a melt index (1.sub.2) of 30 gram/10
minutes and a density of 0.913 g/cc. Resin D is an
ethylene/1-octene copolymer, comprising about 40% (by weight) of a
substantially linear polyethylene component having a melt index of
about 30 g/10 minutes and a density of about 0.915 g/cc and about
60% of a heterogenous Ziegler Natta polyethylene component; the
final polymer composition has a melt index of about 30 g/10 minutes
and a density of about 0.9364 g/cc. Resin E is an ethylene/loctene
copolymer, comprising about 40% (by weight) of a substantially
linear polyethylene component having a melt index of about 15 g/10
minutes and a density of about 0.915 g/cc and about 60% of a
heterogenous Ziegler Natta polyethylene component; the final
polymer composition has a melt index of about 22 g/10 minutes and a
density of about 0.9356 g/cc. Resin F is an ethylene/1-octene
copolymer, comprising about 40% (by weight) of a substantially
linear polyethylene component having a melt index of about 15 g/10
minutes and a density of about 0.915 g/cc and about 60% of a
heterogenous Ziegler Natta polyethylene component; the final
polymer composition has a melt index of about 30 g/10 minutes and a
density of about 0.9367 g/cc. Resin G is an ethylene/1-octene
copolymer, comprising about 55% (by weight) of a substantially
linear polyethylene component having a melt index of about 15 g/10
minutes and a density of about 0.927 g/cc and about 45% of a
heterogenous Ziegler Natta polyethylene component; the final
polymer composition has a melt index of about 20 g/10 minutes and a
density of about 0.9377 g/cc. Resin H is homopolymer polyproylene
having a melt flow rate of 25 g/10 minutes in accordance with ASTM
D-1238 condition 230.degree. C./2.16 kg.
[0092] Resins D, E, F, and G can be made according to U.S. Pat. No.
5,844,045, U.S. Pat. No. 5,869,575, U.S. Pat. No. 6,448,341, the
disclosures of which are incorporated herein by reference. Melt
index is measured in accordance with ASTM D-1238, condition
190.degree. C./2.16 kg and density is measured in accordance with
ASTM D-792.
[0093] Nonwoven fabric was made using the resins indicated in the
table mentioned below and evaluated for spinning and bonding
performance. The trials were carried out on a spunbond line which
used a Reicofil III technology with a beam width of 1.2 meters. The
line was run at an output of 107 kg/hour/meter (0.4 g/min/hole) for
all polyethylene resins and 118 kg/hour/meter (0.45 g/min/hole)
with the polypropylene resin. Resins were spun to make about 2.5
denier fibers, corresponding to the fiber velocity of about 1500
m/min at 0.4 g/min/hole output rate. A mono spin pack was used in
this trial, Each spinneret hole had a diameter of 0.6 mm (600
micron) and a L/D ratio of 4. Polyethylene fibers were spun at a
melt temperature of 210.degree. C. to 230.degree. C., and
polypropylene fibers were spun at a melt temperature of about
230.degree. C.
[0094] The embosses roller of the chosen calendar had an oval
pattern with a bonding surface of 16.19%, an areas amount/cm.sup.2
of 49.90, a land are width of 0.83 mm.times.0.5 mm and a depth of
0.84 mm: For the polypropylene resin the embossed calendar and
smooth roller were set at the same oil temperature. For
polyethylene resins the smooth roller was set 2.degree. C. lower
than the embossed roller (this was to reduce tendency of roller
wrap). All calendar temperatures that are mentioned in this report
were the oil temperature of the embossed roll. The surface
temperatures on the calendars were not measured. The nip pressure
was maintained at 70 N/mm for all the resins.
TABLE-US-00004 Flexural Basis Bonding Mono Rigidity Elongation
Tenacity Weight Temp or bicomponent Abrasion (nMcm) to Peak (N/5
cm); Softness Example # Resin [gsm] .degree. C. filament
(mg/cm.sup.2) MD; CD Force % MD; CD (SPU) 1 100% H 20 145 mono
0.183 0.7; 0.3 63.8; 78.25 49.73; 37.18 0.7 2 100% A 20 130 Mono
0.997 0.13; 0.05 24.95; 32.93 9.32; 4.10 2.3 3 100% A 28 130 Mono
0.997 0.26; 0.14 65.07; 72.81 20.37; 11.42 2.2 4 100% B 21 125 Mono
0.678 0.08; 0.03 32.63; 45.06 11.08; 5.56 2.7 5 100% B 28 125 Mono
1.082 0.15; 0.08 37.83; 47.48 16.23; 8.1 2.6 6 80% 21 130 Mono 0.53
0.06; 0.03 63.14; 91.56 12.0; 8.8 2.9 A/20% C Compounded 7 80% 28
130 Mono 0.56 0.16; 0.07 86.02; 109.51 17.79; 13.22 2.4 A/20% C
Compounded 8 80% 21 130 Mono 0.42 0.07; 0.03 57.98; 86.16 11.45;
8.15 3 A/20% C Dry Blended 9 100% D 20 135 Mono 0.399 0.07; 0.02
71.3; 100.16 7.25; 5.90 3 10 100% D 27 135 Mono 0.491 0.14; 0.06
98.79; 125.78 11.28; 9.54 NA 11 100% E 20 135 Mono 0.411 0.08; 0.03
69.35; 97.99 7.30; 6.09 3.9 12 100% E 27 135 Mono 0.653 0.22; 0.07
89.60; 123.71 11.33; 9.76 NA 13 100% F 20 135 Mono 0.421 0.09; 0.03
75.04; 105.15 7.02; 6.15 3.7 14 100% F 27 135 Mono 0.534 0.22; 0.07
93.45; 118.21 11.36; 9.21 NA 15 100% G 20 135 Mono 0.435 0.08; 0.03
59.55; 96.78 8.25; 7.12 NA 16 100% G 27 135 Mono 0.625 0.19; 0.06
95.89; 116.26 13.23; 11.13 NA
In addition, the nonwoven fabric manufactured can be used by
itself, or for instance in combination with other nonwoven fabrics
or materials such as films. In particular, it can be combined to
form a composite material. After its manufacture, the mono or
multilayered nonwoven fabric can be additionally consolidated,
bonded, laminated and/or mechanically treated, in particular
composited with another material. This can for instance be
accomplished physically, chemically, frictionally coupled and/or
interlocking. For instance, thermal and/or ultrasonic bonding
possibilities may be used. An adhesive can also be used.
[0095] Preferably the nonwoven fabric can be included in a SM or
SMS material, for instance as known from U.S. Pat. No. 5,178,931
and U.S. Pat. No. 5,188,885, or with a melt-blown material, as for
instance known from U.S. Pat. No. 3,704,198 and U.S. Pat. No.
3,849,241. Multilayer materials can also be formed, for instance as
known from WO 96/19346. In the context of this disclosure of the
invention we refer to the documents indicated above, with regard to
the material, the manufacturing process and/or its use. It is also
possible to manufacture two-component materials, for instance as
they are known from U.S. Pat. No. 5,336,552, from U.S. Pat. No.
5,382,490, from U.S. Pat. No. 5,759,926 and from U.S. Pat. No.
5,783,503 and the documents mentioned therein. It is also possible
to manufacture co-extruded fibers as they are known from U.S. Pat.
No. 4,100,324 and U.S. Pat. No. 4,818,464.
[0096] Furthermore, the nonwoven fabric can be stretched by itself
or bonded to at least one additional layer. Here the material can
exhibit elastic properties. The stretching force can here be
applied in CD and/or in MD. Methods and parameters for such
stretching can for instance be found in EP 0 259 128 B1, in U.S.
Pat. No. 5,296,184, in EP 0 309 073 and in U.S. Pat. No. 5,770,531.
It is referred to them in the context of this disclosure in
relation to stretch possibilities.
[0097] The term "nonwoven fabric" refers to a web that has a
structure of individual fibers or threads which are interlaid, but
not in any regular, repeating manner. Nonwoven fabrics can be
formed by a variety of processes, such as, for example, air laying
processes, meltblowing processes, spunbonding processes and carding
processes, including bonded carded web processes.
[0098] The nonwoven fabric might comprise microfibers.
"Microfibers" refers to small diameter fibers having an average
diameter not greater than about 100 microns. Fibers, and in
particular, spunbond fibers utilized in the present invention can
be microfibers, or more specifically, they can be fibers having an
average diameter of about 15-30 microns, and having a denier from
about 1.5-3.0.
[0099] The nonwoven fabric might comprise meltblown fibers. The
term "meltblown fibers", refers to fibers formed by extruding a
molten thermoplastic material through a plurality of fine, usually
circular, die capillaries as molten threads or filaments into a
high velocity gas (e.g., air) stream which attenuates the filaments
of molten thermoplastic material to reduce their diameter, which
may be to a microfiber diameter. Thereafter, the meltblown fibers
are carried by the high velocity gas stream and are deposited on a
collecting surface to form a web of randomly dispersed meltblown
fibers.
[0100] The nonwoven fabric might comprise spunbond fibers,
especially consists spun-bond fibers. The term "spunbonded fibers"
refers to small diameter fibers which are formed by extruding a
molten thermoplastic material as filaments from a plurality of
fine, usually circular, capillaries of a spinneret with the
diameter of the extruded filaments then being rapidly reduced by
drawing.
[0101] The nonwoven fabric might be consolidated. The terms
"consolidation" and "consolidated" refer to the bringing together
of at least a portion of the fibers of the nonwoven fabric into
closer proximity to form a site, or sites, which function to
increase the resistance of the nonwoven to external forces, e.g.,
abrasion and tensile forces, as compared to the unconsolidated
fabric. "Consolidated" can refer to the entire nonwoven fabric that
has been processed such that at least a portion of the fibers are
brought into closer proximity, such as by thermal point bonding.
Such a web can be considered a "consolidated web". In another
sense, a specific, discrete region of fibers that is brought into
close proximity, such as an individual thermal bond site, can be
described as "consolidated".
[0102] Consolidation can be achieved by methods that apply heat
and/or pressure to the fibrous web, such as thermal spot (i.e.,
point) bonding. Thermal point bonding can be accomplished by
passing the fibrous web through a pressure nip formed by two rolls,
one of which is heated and contains a plurality of raised points on
its surface, as is described in the aforementioned U.S. Pat. No.
3,855,046 issued to Hansen et al. Consolidation methods can also
include ultrasonic bonding, through-air bonding, and
hydroentanglement. Hydroentanglement typically involves treatment
of the fibrous web with high pressure water jets to consolidate the
web via mechanical fiber entanglement (friction) in the region
desired to be consolidated, with the sites being formed in the area
of fiber entanglement. The fibers can be hydro-entangled as taught
in U.S. Pat. Nos. 4,021,284 issued to Kalwaites on May 3, 1977 and
4,024,612 issued to Contrator et al. on May 24, 1977, both of which
are hereby incorporated herein by reference. In the currently
preferred embodiment, the polymeric fibers of the nonwoven are
consolidated by point bonds, sometimes referred to as "partial
consolidation" because of the plurality of discrete, spaced-apart
bond sites.
[0103] Because of its characteristics, the nonwoven fabric can be
used in the most varied applications, which are here reflected
merely as examples, without claim to completeness.
[0104] The nonwoven fabric can be used in absorbent articles. The
term "absorbent article" refers to devices which absorb and contain
body exudates, and, more specifically, refers to devices which are
placed against or in proximity to the body of the wearer to absorb
and contain the various exudates discharged from the body. The
nonwoven fabric can also be used in disposable articles. The term
"disposable" is used herein to describe absorbent articles which
are not intended to be laundered or otherwise restored or reused as
an absorbent article (i.e., they are intended to be discarded after
a single use and, preferably, to be recycled, composted or
otherwise disposed of in an environmentally compatible manner). A
"unitary" absorbent article refers to absorbent articles which are
formed of separate parts united together to form a coordinated
entity so that they do not require separate manipulative parts like
a separate holder and liner.
[0105] Further use of the nonwoven fabric is possible: In the
medical area, for instance in a Stoma bag, coverings, gowns, face
masks, ladies' and babies' hygiene articles, for instance back
sheets, or also as top sheets, which for instance may also have a
coating, in sanitary towels, incontinence articles, printable
coverings, protective surfaces, packaging materials, as separators,
as vapor-permeable but water-tight materials, as adhesive material
for instance in the use of microloops and locking devices, as
fastening material in closure systems, as contact surface for an
adhesive, as contact agent between two surfaces, for instance a bed
and a bed cover, as part of a wall hanging or carpet or floor
material, as cleaning or polishing agent, in protective clothing,
for instance an overall, in applications close to the skin. Also as
oil and/or lubricant collector and/or as cleaning agent, in sport
clothes, sport accessories and/or sport equipment, or shoes, in
clothing items such as gloves, coats, etc., as packaging, for
instance for bottles, CD wrappers, as wrapping, as decoration, in
the automobile domain, in the fittings area, as covering material
to wrap articles, as a coating, as roofing material, as noise
and/or thermal insulation, as filtering agent or sedimentation
agent, as identification agent for instance in creme application
fabrics, as storage medium for substances that during subsequent
use are suddenly or gradually released, for instance by diffusion,
as eyeglass cleaning fabric, as loading medium for particles and/or
powders, as intermediate layer in hygiene articles, in the sanitary
area, for instance in towels, in bathing caps, as drainage agent,
as color-coding agent, as signal marker, as seat cover, as wound
covering material, in elastic bandages, as cigarette filter, as
surface material in a disposable article, as covering material for
painting, coating and similar work, to grow cell cultures, in
elastic materials, for instance in hygiene articles as sidebands,
waste-bands and/or also elastic closures, in suction pads, as well
as in other applications, e.g. house-hold applications like wipes,
especially wipes comprising or consisting of at least one nonwoven
fabric layer as mentioned
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)
[0106] Having thus described the invention in general terms,
reference will now be made to the accompanying drawings, which are
not necessarily drawn to scale, and wherein: Other advantageous
implementations and further developments can for instance be
derived from the drawings below. The examples there illustrated
should not be viewed as limiting. The characteristics described
there can rather be related to other implementation forms.
[0107] FIG. 1: is a schematic view showing a first spinning system
that operates according to the Lurgi-Docan process,
[0108] FIG. 2: is a schematic view showing a second device for the
manufacture of spunbond nonwoven fabrics,
[0109] FIG. 3: is a top view showing a first spinning plate,
[0110] FIG. 4: is a top view showing a second spinning plate,
[0111] FIG. 5: is a cross-section all view,
[0112] FIG. 6: a cross sectional view of a first product,
[0113] FIG. 7: cross sectional view of a second product,
[0114] FIG. 8: a cross-section through a nonwoven fabric fiber,
and
[0115] FIG. 9, a cross-section through bicomponent fibers.
[0116] 10, 11:
DETAILED DESCRIPTION OF THE INVENTION
[0117] The present invention now will be described more fully
hereinafter with reference to the accompanying drawings, in which
some, but not all embodiments of the inventions are shown. Indeed,
these inventions may be embodied in many different forms and should
not be construed as limited to the embodiments set forth herein;
rather, these embodiments are provided so that this disclosure will
satisfy applicable legal requirements. Like numbers refer to like
elements throughout.
[0118] FIG. 1 shows a first device 1 for the manufacture of
nonwoven fabric fibers 2. In an extruder 3, polymer sent to the
extruder 3 is melted and sent to a spinning package 5 through an
extruder head 4. The extruder head 4 and the spinning package 5 can
be heated independently of each other. A spinning plate 6 is
included in the spinning package 5. The polymer 7 coming from the
extruder is pressed through the spinning plate 6. As it exits the
spinning plate 6, the polymer continues as individual threads,
which are cooled and stretched by means of quenching device 8. The
quenching device provides for a quenching medium 9, indicated by
arrows, to cool the polymer threads 10 coming out of the spinning
plate 6. After passing through this one-piece quenching segment 11,
the polymer threads 10 are sent into a gap area 12. In the gap area
12 first a propelling agent is introduced, for acceleration. In
particular this can be driving air. Farther downstream a spreading
medium 14 is introduced, to spread the polymer threads 10 in a
downstream diffuser area 15. The nonwoven fabric fibers 16 thus
stretched and spread can then be deposited on a device not further
shown, for further processing. With the device described and
properly chosen parameters it is possible to manufacture a nonwoven
fabric as described above. To this end a bonding facility is added
downstream of the first device 1, in particular a calender system,
so that the nonwoven fabric can be manufactured in a single
process, from polymer melting to processing to nonwoven fabric
fibers, to consolidation in a calendering system.
[0119] FIG. 2 shows a second device 17, that includes an extruder
18. The extruder 18 has a first segment 19, a second segment 20, a
third segment 21, a fourth segment 22 and a fifth segment 23. The
segments 19-23 can each be heated separately. In addition, the
extruder 18 has a heated extruder head 24. The melted polymer is
sent under temperature control to the spinning package 25, through
the extruder head. The polymer 27, under pressure, is sent to the
chamber 28 via the spinning package 25 and through the spinning
plate 26 that is part of the spinning package 25. The chamber 28
has an outlet placed across from the spinning package 25. This
outlet can in particular be in the form of a gap, as illustrated.
In particular, the gap width 29 is adjustable. The outlet 28
preferably opens into an enclosure 30 that preferably has a
diffuser area 31. The diffuser area 31 allows spreading the
nonwoven fabric fibers 32 when they are deposited. Next to the
diffuser area and in particular, preferably sealed off of it, a
first 33 and a second roller area 34 is arranged. The roller areas
33, 34 are preferably such that they facilitate improved suctioning
off of the quenching medium by the deposition facility 35. In
particular, a suction system 37 can be arranged underneath the
screen belt 36 of the deposit facility 35. The suction system 37
can preferably be adjusted to different removal volumes, by changes
of the suction mechanism 38. The deposited nonwoven fabric fibers
32 are next compacted or consolidated in a calender 39, in
particular thermally bonded. To this end the calender 39 has an
engraved roller 40 and a smooth-surfaced roller 41. Between the
engraved roller 40 and the smooth-surfaced roller 41 an embossing
gap 42 is formed, where its nip pressure can be adjusted. The
nonwoven fabric can be spooled on a downstream spooling device 43
and stored or further processed as a spool.
[0120] On the screen belt 36, upstream of the second device 17, it
is possible to install a not further illustrated let-off device, or
some other layer manufacturing system. It would thereby be possible
in an in-line process, for instance, to supply a support 44, on
which the spunbound nonwoven fabric could be deposited and
subsequently bonded.
[0121] FIG. 3 shows a first spinning plate 45 in a schematic view.
The borings 46 in the spinning plate 45 are arranged in parallel
rows and lines perpendicular to each other. In particular, only the
borings, or also the entire spinning plate can have a coating
47.
[0122] FIG. 4 shows a second spinning plate 48 in a schematic view.
Here the borings are arranged in a staggered fashion. As shown, the
distances can be displaced by 50%. However, the distances can also
be different, for instance 1/3, 1/4 or 1/5.
[0123] FIG. 5 shows a schematic cross-section through as third
spinning plate. Different boring geometries that can be used are
here shown in simplified form. In addition, the L/D ratio can be
obtained from the cross-section. If the diameter D changes along
the length L, then the mean diameter is determined. It is obtained
by adding all partial diameters and multiplying by the
corresponding partial lengths and next dividing the result by the
overall length L.
[0124] FIG. 6 shows a cut-out of a first product 51. The product 51
has a polyethylene nonwoven fabric 52 according to the invention on
its surface 53. The product can for instance be a two-layer
material, as shown. The laminate can for instance be a
film/nonwoven fabric laminate.
[0125] FIG. 7 shows a cut-out of a second product 54. The second
product 54 is a SMS material, for instance, the layers of which are
thermally bonded to each other. Preferably the layers have not only
been bonded to each other but also individually consolidated, in a
single process. Here at least one of the spunbound nonwoven fabric
layers is a nonwoven fabric according to the invention, with a
polyethylene surface.
[0126] FIG. 8 shows a cross-section through a nonwoven fabric fiber
55. It shows a core 56 that preferably contains polypropylene. A
surface 57 of the nonwoven fabric fiber has polyethylene at least
on parts of it. The polyethylene can cover the entire surface, in
particular with changing surface geometry, or cover the core 56
discontinuously, as casing 58. If there are discontinuities, they
can advantageously be equipped with an oxidation layer, for thermal
bonding.
[0127] FIGS. 9, 10 and 11 each show different cross-sections
through a two-component fiber. In addition to being a fully
polyethylene material-covered fiber, the two-component fiber offers
the advantage of allowing the influencing of desired properties of
the nonwoven fabric by the choice of the other polymers, for
instance the tensile strength. In the nonwoven fabric fiber show,
polyethylene forms the surface, at least partially and in
particular, completely.
[0128] Many modifications and other embodiments of the inventions
set forth herein will come to mind to one skilled in the art to
which these inventions pertain having the benefit of the teachings
presented in the foregoing descriptions and the associated
drawings. Therefore, it is to be understood that the inventions are
not to be limited to the specific embodiments disclosed and that
modifications and other embodiments are intended to be included
within the scope of the appended claims. Although specific terms
are employed herein, they are used in a generic and descriptive
sense only and not for purposes of limitation.
* * * * *