Note: Descriptions are shown in the official language in which they were submitted.
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MET1iOD AND DEVICE FOR PRODUCING A FIBER WEA CONSISTING OF CELLULOSE
FIBERS FOR USE IN HYGIENE PRODUCTS
'rhe invention relates to a method for producing an absorbent fiber web and a
device for producing a
fiber web consisting of cellulose fibers for use in hygiene products, in
particular, personal, absorbing
hygiene products. The invention further relates to an absorbant fiber web
manufactured according to
this method.
It is known to combine cellulose-containing material such as wood or plant
fibers into a fiber web by
employing a combindtiun of inechanical and chemtcal processing strps under
intensive lwaung while
excluding oxygen. The aim of such a process is to avoid rhe use of binding
agent additives Cuher
conzpletely or to a larbe extent According to one of these known methods (US A
1 4,111,744), ceAulose
fibers wich a rnoisture content of 3 to 12 percent in weight are subjected to
pressurr in an oxygen-free
aunosphere at a temperature of 450 to 800 F (= 232 to 426 C), which is a
high temperature
environment beyond the cellulose carbontzing temperature and cellulose
combustibility trmperature.
Paper-type products may also br manufactured usiug the aforementioned lmowu
tnetftod, but, aniy that
of stiff cardboard
The disadvantage of Llus method is that a considerable technological effort
needs to be invested to heat
the pressuri2ed spacc and to prevent combustion of the material through oxygen-
free tnanufacturing.
Also known is a methocl (WO 94/10956) for producing under pressure absorbetu
web products from dry
cellulose fibers and additives by compressing a material with a weight per
tuut area of 30-2000 g/cm' to
a producc with a dCnsity of 0.2-1.0 glcm'. Compressing is carried out using
stnooth calettdcr rollers. The
disadvantage of this method is rhat although rhe density is increased, the
tear strength of the tuateiial
icself is low. Synthenc additives, especially theromplasts, must be added to
increase the tear suength.
It is further knowu from US-A 3 692 622 to initially fornr an irregular
cellulose fiber l8yer and under
relatively low pressure to produce a lcxnc non-woveti fabric with a low
density and tear strength. The
loose non-woven is theu entered into the gap of an additional pair of caleader
rolls and embossed with a
pattrru of point- or lute-shaped pressure zottes_ The result is a soft,
absorbent web utaterial with a base
weight of about 16.9 to 50.9 g/m'. The tear strength of this fiber web is
about 0.09 !cN/m. Thus, it is a
materixl that rears easily as is the case witn iacia! tissaes, for example.
The calender pressures applied
for this known product axe about 2,000 to 10,000 psi corresponding to 14 to 69
MPa. Thr US-A
docurnent speaks of resultant hydrogen bundtng, as is also the result in self-
bonding conventional paper
products.
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The fiber web manufactured by the mCthod is said to be particularly suitable
for manufacturing hygiene
products. it is said to be vCry absorbing, soft and capable for processing as
a web. Single-use hygiene
articles such as diaper panties and such are tnanufactured in high volume. The
core absorbing layers
used for these products should be tolerated well by the body, the absorbed
liquids well distributed, and
after use, thr products should rot in landfills without residue. A known
method is to manufacnue the
absorbing layer of a wood cellulosr fiber rnatrix, where so-called
superabsorbers can be added to this
fiber matrix to increase rbe liquid absorption capacity. Superabsorbers are
polymers that can absorb
water by building hydrogels
It is the objective io specify a method for producing a fiber web made of
cellulose fibers, where
essentially no btnding agents need to br used, and were the process can be
carried out ai room
temperaturCs under normal atmospheric pressure and with thC oxygen content of
ambient air.
This objective is accomplished with the method for manufacturing a fiber web
made of cellulose fibers,
which is largely tear resistant, absorbent and rollable, using the processing
steps according to the
features of claizn 1.
It is assumed that in the technology of producing cellulose fibers it is known
to make them of a wood
derivative known in the industry as "fluff pulp". This material is a
standardized wood product made of
cellulose material shtpped in boards or webs, so-called wood pulp cardboards,
where said material is
crushed in a hammer mill and separated into fibers until it turns into a
cotton-like product of ceiluiose
fibers, namely fluff pulp. A description of such a standardized crushing
process can be found, for
exainple, in the brochure of the company Dan-Webforming International A/S.
Risskov, Denmark.
This wood derivative called "tluff pulp" is a product that is used in large
quaatities in the so-called
water-less paper production. Preferably, the fibers have a length of about 1
to 5 rtun as they exit the
bammer inill. According to the first step of the aforementioned process, they
are embedded irregularly in
a cellulose riber layer with a height of 5 to 15 mm and are preferably sent on
a conveyor belt io a
movable strainer tluough a pre-condenser station that consists preferably of a
pair of calender rolls with
low pressure, such tl-at the result is a loose non-woven with low density and
tear strength. The tear
strength is dimensioned such that the non-woven can sag over a lerigth of 0.1
to 1 m without tearing. It
can also withstand air pressures that occur during the production_
This essentially known and still very loose non-woven is inserted into a gap
of a pair of calender roAs,
where a sigruricant pressure is applied in the point-shaped pressure zones.
The pressure must be at least
100 and should be about 520 MPa (MPa = N/mm) The liquid limit of the material
used for the rollers
is geucrally the upper pressure limit. Acuording to the state-of-the-an, such
high pressures have not been
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used until now. To produce such a pressure, rollers may be used with studs,
with line patterns offset
from one anozher or wirh other protruding point- or line-shaped pressure
surfaces, where the array
density of the point-shaprd pressure zones is between 1 and 16 array points
per cm2.
A fiber web, preferably with a m= weight between 50 g and 1500 g, is produced
according to the
method. Due to the discribution of the cotulecting points, this new fiber web
has become so strong that a
tear suengih of at least 0.12 kN/m, preferably of up to 0.65 kN/m, is
achieved. The thickness of the
fiber web is dependent on the desired metrage.
The size of the pressure area of the puint-shaped pressure zones is dependent
on the pressure that can be
achievzd between the second calender rollers. Poini-shaped pressure zones with
areas between 0.05 and
mm= have proven sutficient.
As has already been emphasized, the tCtnperature of the second pair of
calender rolls should be
maintained at room temperature, that is, between 19 and 25 C. The operation
can also take place at
higher tempcrarures. It should be noted that the temperature will increase in
the pressure zones due to
the significant use of power.
Pre-:ompression should talce place at a tool crmperature of between 18 and 320
C, preferably between
250 and 300 C. Preferably, thz pre-compression tool is a pair of calender
rolls that can be heated_
The fiber and/or the loose non-woven are brougtu to a certain moisture content
before entering the
calender rolls, whrrr preferably the moisture conteni should be set to between
2 and 9 percent in weight,
at a rqinimum to 1 5 percent in weight.
Starting triaterial is thC aforemei-tioned iluff pulp wood derivative.
Preferably, this is a srandardizA
dehbered product, such as the one also used in rnanufaczuring fiber webs
according to lactowu methods.
Sulfite or sulfate bleached long fiber cellulose of northern wood appears very
advan,tageous.
It has also proven ac3vantageous, when r.he cellulose fibers were not bleached
to totai whiteness but
instead when they still contained a certain content on natural wood materials.
The degree of whiteness
should be between 80 and 92 %, preferably between 85 and 89 %. A certain
remaining lignin contetu
has shown to be advantageous as well, for example if it is between 0.5 and 5
percent in weight of the
starting matzrial_
Non-binding, tnorganic pigments or tillers, such as titanium oxide, kaolin or
zeolithe can be added ta the
stdrting material.
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A certain amount of superabsorbers can be added to the starting fibers as
well, where the acrylate
composites known as superabsorbers can be added in powder forYn to the fluff
pulp in an atnouru of, for
example, 0.5 to 70 percent in wright (in relation to the total arnount) and
where the manufacturing
process is not significantly influCnczd by this.
In the pressure zone of the second calender roll, the radial distance of the
calender roll pair beyond the
actual point-shaped pressure zones should be about 1 to 15 mm such that the
material beyond the
pressure zorie is not squashed during the pressure application, but is rather
fluffed and somewhat
compressed.
The gap in ttie pressure zone of the second pair of calencler rolls is
dependent on the metrage and the
thickness of the inscrted loose non-woven. In general, the gap should not
exceed a clear width of 0.45 to
1 tnttt.
A signifrcant part of the device for carrying out the method is formed by tbe
second pair of ealetalrr
rolls, whtch is prrterably made up of two steel calender rollers both provided
with nwnerous studs
distributed across the outer surfaces of ttie rollers corresponding ta point-
shaped pressure zones that are
surrounded by indentations tlhat rxhibit d rnultiple of the volume of the
raised areas. In the operacing gap,
the raised areas of the two rollers are opposite one another, and a pressure
of at least 200 MPa up to the
maximum liquid lirnit of the materiat used for the studs is exerted on the nnn-
woven located in the point-
shaped pressure zones.
The preferable heighr of the studs or other pressure zones is between 0.5 and
15 mm from the roller
base. The studs are preferably shaped as pyramzds or truncated cones with a
snul coat angle of 10 to 45
in relation to the radius. Line-shaped or similar pressure zones are possible
as well.
The irregularly arranged fibers are compressed under very high localized
pressure in line or point-
shaped pressure zones, such that a multitudr of close fusions of the fiber
bodies occur that will not
separate after the pressure is released. A product of numerous irregular
cellulose fibers is produced,
where said fibers are connected in the pressure zones through fiber bonding.
The fiber web has sufficient
tear strength and also a high absorption capacity such that it is ideally
suited for hygiene products.
It has shown that in order to meet the specific requirements of the hygiene
industry, the web of fiber
materials must subsequently be combined with suitable materials in a labor-
intensive manner. Thus, the
additional objective is given to specify au addttionat method for producing a
fiber web consisting of
cellulose fibers rhat is e9uipped with, for example, increased tear strength,
densiry or breathing and/or
insulating capacities.
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The methods and apparatus in the claims will become more readily apparent
through the description of
exemplary enibodiments with reference being made to the accompanying drawings,
wherein
Fig. 1 shows a schCmat:c presentation of a device for producing a fiber web
made of cellulose fibers;
Fig. 2 shows in an enlarged presentation according to Fig. 1, the cross-
section of the pressure zone of
two rollers with pyratnid=shaped studs;
Fig. 3 shows a perspective prCnientation of a section of the product
truuutfaetured according to the
method;
Fig. 4 shows an enlarged presentation of the pressure zones of the fiber web;
Fig. 5 shows a schematic presentatton of a different device for producing a
fiber web with two
additional synshetic layers,
Fig. 6 shows a schematic prrseniation of yet another device for producing a
fiber web with a synthetic
coatinb;
Fig. 7 shows a presentation sunilar to Fig. 2 of a cross-section of the
pressure zone of two rollers with
an inserted fibrr web with a foil placed on it.
Fig. I shows in a schrmatic sequence an arrangement of roAers and rolls for
carrying out the tnethod.
The production process starts with cellulose fibers made of fluff pulp,
preferably of dry wood pulp
cardboards by means of a hammer mill, which is described in great detail in
the state-of-the-art presented
in the aforeinentioned brochure of Dan Webforming international A/S.
A layer of irregular fibers 1 in a height of about 20 mm is conveyed to a
first pair of calender rollers
4.1, 4.2 on a strainer conveyer belt 8. The upper roller 4.1 has a surface
temperature of about 220 C,
whiie the bottora roIler is unheated. The web is tnoisturized by spraying from
above using a moisturizing
device 3 prior to entering the gap between the two rollers 4.1 and 4.2. The
rrsuitauc moisture of the
material is about 5 to 10 percent in weight.
A portion of the moisture is elirninated biltween the calender rollers 4.1 and
4.2, aad the irregular
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eellulose fiber layer is corupressrd to a loosc uon-woven with low density and
tear strength. However,
the tear strength is sufficient that ttie non-woven 2 does not tear when
bridging the distance between the
end of the strarrrer beli 8 and rhe reversing roll 7 to the inlet into the gap
between the two additiondl
calendCr rolls 6.1 and 6.2, which is about SU cm.
The first processing step is simply a prC-compresston or compacting of the aon-
woven from the
irregularly arranged tibers. A fixcd web is not produced and it is entirely
possible to remove thx fibers
iadividually, piece by piece. Thr tear strength of the non-woven is very low,
prrferably at least 8 N/tn
wide.
The non-wovert 2 providCd by the strainer belt 8 is again rwisturrzed from top
and bottom (maisturizing
device 5) prior to entering the gap between the two calender rolls 6_ 1 and
6.2.
Between the calender rolls 6.1 and 6.2, the inuially loose non-woven is
subjected to an array of point-
shapod pressure zones, where the irregularly arranged fibers are pressed onto
each other under high
pressure, such that a close fusion of the tiber bodies occurs and a fiber web
100 with an etnbossed
pattera is created that will not separate etier the pressure is released. The
roller arrangement cau also be
termed as "pixel rollers".
Carbonization of the fiber material is avoided. However, it is obvious that
the pressure is sufficiently
high to practically melt the matertals constituting the fibers, ihat is,
cellulose and reniaining ligniit and
other materials, wlterr such close bonding occurs that goes beyond the bond of
simple adhesion.
Through point-tocused high pressure and crowding of the fibers, the loose
c.ellulose or pulp fibers are
bonded together in all existltig free spaces, additionally glued and
interlocked, resulting in an overail
very strong fiber web.
Rolls 6.1 and 6.2 are operated at regular room temperatures, thar is, between
18 and 25 C, however it
should not be rxcluded ehat tha rollers may be heated or that a higher
temperattue may be reached at the
point-shaped and also point-focused pre ure zones due to the high mechanical
energy. The pressure
affectutg the cellulose fiber layer in the puitu-shaped pressure zones 17 (cf.
Fig. 2) is preferably above
500 MPa, but defittitely in a range of 100 to 600 MPa, even higher with a
respective technoiogical
effort.
With this method, fiber webs with a mZ weighr between 50 and 1500 g, for
exaruple, can be produced.
The fiber web exiting the calenders is significantly tttore tear resistaru
than the web eatering the caleader
rolis 6.1 atu16.2 The material is treated with broad drawing roller 9.
Thereafrer, it is wrapped otuo a
take-up rolirr 11 with the use of a driver roller 10.
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Foremost, the material used should be an inexpensive mass material that is
available in large amounts.
Fluff pulp witti a whiteacss of 85 to 89 % is the preferred choice, which in
turn means thaz a signific,ant
lignin and residue content is still present. It has been shown that such
residues significantly improve the
bonding behavior. Experience shows thar cellulose bleached entirely has a
worse bonding behavior ihau
less pure cellulose. The titer should nor be below a certain length because
fibers that are too short cannot
bridge the distance between the point-thaped pressure zones such that low rear
szrength is achieved with
low titer.
SuppleAaentary additives are also dirtwnsionrd according to the desired tear
strength. The addition of so-
called super-absorbers, as described in the document WO 94/10596, for example,
is relarively uneritieal.
Fluff pulp can be supplemented with superabsorbers with 0S to 70 percent in
weight, preferably 5 to 30
percent in weight, and thereafter sent through the high-pressure calender
rolls 6. The superabsorbers
have tuw bonding effect; tou large an amounr will reduce the tear strength.
However, the addition of crushed non-bonding inorganic materials, such as the
whire pigrnent titanium
oxide, reduces the tear strength such that, in general, a percentage of 25
percent in weight of titanium
oxide should noi be exceeded. A similar rule applies to fillers such as kaolin
and zeolithe.
It is important that binding agents such as are lcnown from the state-of-the-
an, which are generally
required, can be avoided almost entirely. "T'his significantly improves the
recycleability and
cornpostability of thr product. The production becomes less expensive and is
simpler because stations for
applying and curing are not required. However, it shall not be precluded that
the finishad product can be
provided with a surface tinish or larninated with a film on one or both sides
afier running through the
calender rollers 6.1 and 6.2.
Fig. 2 shows an exemplary embodiment of a high pressure zone between the two
calender rollers 6.1 and
62. As can be sren, thr outer roller surface is provided wirh studs 14, shown
in an enlarged
presentation. The numerous studs distributed across the entire outer roller
surface result, preferably, in
an array density of thr point-shaped pressure regions of between 1 and 16
array points per cm2 for the
fuzished fiber web. The studs have the shape of a truncated pyramid with a
stud coat angle of 10 to 45
in relation to the radius. A calculated pressure of a bout 520 MPa, which
leads to the aforementioned
fusion of thC celiuluse fibers in the gap, is present in the gap 12, where the
pressure zone 17 is created.
Other shapes of the pressure zones, such as truncat.ed cones, cylinders or
cubes are possible and are
selected according ro professional opinions according to the required
pressure, thc respective stanitig
material and the material uf the rullers, the temperatures that occur, etc.
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In the preseut case, the direction of the operation is from left tv right.
Thus, the fuushed product exhibits
almost lucid fusion zones 18, thai alternate with sonwwhat tluffy loose
regions 19 that are, however,
compressr,d when compared to the starting non-woven.
Fig. 3 shows the finished product, consisting of nurmerous irregular cellulose
fibers that arr connected by
fusion in the pressure zones 18. The niaterial itself has a high tear strength
and, in addirion, a high
absorption capacity, which is increased evrn further through thr use of
superabsorbers such that it can be
used as packagitig material, for hygiene products, lining ruaterial, pillow
filler and similar products. The
material can also be used in the construction industry as a well as
replacernent for paper and cardboard.
The aforCmentioned products can also be used for napkins, tampons, baby diaper
panties, slip inserts,
sanitary napkins, and incontinence products
Fig. 4 shows an enlarged przsentation of a pressure zone 17 in an electron
microscope image. In this
case, the pressure 2one has a hexagonal shape that has been caused by the
insertion of a stud 14 into the
non-woven. The pressure applied in this case is 190 MPa (= 190 N/mm). It can
be seen that the
initially routui and undamaged fibers 29 are flat and smooth in the pressure
zone dtre to the pressure.
The superabsorber particles that were present are optically no longer
recognizable, because they have
obviously been pressrd into the surface. The fiber structure can still be
recognized sotnewhat in the
portion of the zones 27 inside the pressurC zone 17, while other zones 28 are
present where a fiber
structure can no longer be recognized. Ttie fibers pressed onto one another
can no longer be separated
from one another when trying to do so with a dissecting needle. Thus, a
fusiou, compacting and gluing
with surface bonding of thr fiber and/or cellulose substance has occurred with
the pressure being kept
under the carbouization limit of the fibers 29.
Fig. 5 shows a schematic sequence of an arrangement of rollers and rolls where
the method is carried
out using a second embodimCnt. A layer of irregular fibers 1 in a height of
about 20 mm is conveyed to
a first pair of calendrr rollers 4.1, 4.2 on a strainer conveyer belt 8. The
upper roller 4.1 has a surface
temperature of about 250 C, while the bottom roller is unheated. The web is
moisturized by spraying
from above using moisturiztng device 3 prior to entering the gap between the
two rollers 4.1 and 4.2.
The resu]tant moisture of the material is about 5 to 10 percent in weight.
A portion of the moisture is elimir,ated between the calender rollers 4.1 and
4.2 and the irregular
cellulose fiber layer is compressed w a loose non-woven with low densiry aud
tear strengrh_
8etween the calender rolls 6.1 and 6.2, the initially loose non-woven is
subjected to an array of point-
shaped pressure zones where thC irregularly arranged fibers are pressed onto
each other under high
pressure such that a close fusion of the fiber bodies occurs and a fiber web
100 with an embossed pattern
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is created that will not separatr after the pressure is released.
After passing the calender rollers 6.1 and 6.2, the fiber web 40 is on both
sides glued to, welded to
attdlor mechanically connected to wCbs 20.1 and 20.2 made of textile, non-
woven-type ar foil-type
tnaterial. ThC pre-fabricated coating webs 20.1, 20.2 have - as far as
necessary - already been coated
with adhesive, and are guided from above and below onto the fiber web that
exits from the calender
roller pair 6.1, 6.2 and fused to it using the pressure roll pair 9.1, 9.2. A
mechanical connection of the
coating with thz fiber material is also possible using pressure rollers 9.1,
9.2 provided with embossing
elements. Gluing with a hot adhesivC is possible as well. The composite is
wrapped onto a take-up roller
11 with the use of a driver rollrr 10_
Fig. 6 shows in a schematic sequence an arrangement of rollers and rolls for
carrying out the method in
an additional embodiment. The production process stans with cellulose fibers
utade of fluff pulp that has
been made of dry "wood pulp" using hammer mills.
Similar to Fig. 1, a IayCr of irregular fibers 1 in a height of about 20 mm is
conveyed to a first pair of
calertder rollers 4.1, 4.2 on a strainer conveyer brlt 8. The upper roll 4.1
has a surface temperature of
about 180 C, while the bottom roller is unheated.
The irregular cellulose fiber web is cornpressed between the calender rollers
4.1 and 4.2 to a loose non-
woven with low density and tear strength. Prior to entering the gap between
the two calender rolls 6.1
and 6.2, the non-woven 2 provided by ttie strairier belt 8 is covered from the
top with a tlun (10 m) foil
30 made of PTFE that initially is not perforated (PTFE = polyfluorethylen).
Between the calender rolls 6.1 and 6.2, the non-woven covered with the PTFE
foil is subjected to an
array of point-shaped pressure zones where the irregularly arranged fibers are
pressed onto each other
under high pressure such that a close fusion of the fiber bodies occurs and a
fiber web 100 with an
embossed panern is created that will not separatC after the pressure is
released; the foil, which is
relatively heat-resistant is included in the composite. Carbonization of thC
fiber or foil material is
prevented. The sintering or bcbinning-to-rnelt foil material achieves
additional bonding.
Rolls 6.1 and 6.2 are operated ar regular room temperatures, that is, between
18 and 26 C, however it
should not be precluded that the rolls rnay be hearxd or that a higher
temperature may be reached at the
poitu-shaped and point-focused pressure zonzs due to the high mechanical
energy.
The pressurt affecting the cellulose fiber layer with the foil placed on it in
the point-shaped pressure
zones 17 (cf. Fig. 4) is preferably above 300 to 400 MPa . After passing
through the calender rollers 6.1,
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6.2, the fiber web is on one side connect,ed with a foil web. The composite is
wrapped onto a talce-up
roller 11 with the use of a driver roller 10,
An additional coating web 20.2 has - as far as necessary - already been
c:oated with adhesive, and is
guided from below onto the wCb that zxits from the calender roller pair 6.1,
6.2 and fused to it using the
pressure roll pair 9.1, 9.2 (cf. Figure 6). The composite is wrapped onto a
take-up roller 11 with the use
of a driver roller 10.
Fig. 7 shows an exemplary erubodiruent of a high pressure 2one between rhe two
calender rollers 6.1 and
6.2. As can be seen, the outer roller surface is provided with studs 14 shown
in an enlarged presentation.
The numerous studs 14 distributed across the entire outer roller surface
preferably result in an array
densiry of the point-shaped pressure regions of between I and 16 array points
per em' for the finished
fiber web. The studs have the shape of a truncated pyramid with a stud coat
angle of 10 te 45 in
relation to rhe radius. A calculated pressure of a bout 520 MPa, which leads
to the aforementioned
fusion of the cellulose 2ibers in the gap, is present in the gap 12, where the
pressure zone 17 is created.
Other shapes of the pressure zones, such as truncated cones, cylinders or
cubes are possible and are
selected according to professional opiruons according to the required
pressure, the respective starting
material and the material of che rollers, the temperatures that occur, etc.
Foi130 can be calendered or
laminated ai the samr time.
For Fig. 7, iaie direction of the operation is from left to right. Thus, ihe
finished product exhibiis almost
lucid fusion zoi,es 18, that alternate with somewhat fluffy loose regions 19
that are, however,
compressed when compared to ttie starting non-woven.
The coating methods are described in greater detail based on the following
examples:
Example 1
A fiber web 100 (cf. Fib. 3) is combined on one side with a web of woven
textile material. On the
surface pointing t.o the fiber web, the textile web is provided with a Hotmeit
adhesive, such that a good
adhesive bond is produced after passing through the pressure rolls 9.1, 9.2.
Because of the fiber
material, such a composite exhibits good heai insulating effecis and can
withstand greater rnechanical
forces due to the woven textile web.
Exemple 2
The fiber web 100 produced according to the description of Figures 1 to 3 is
at its uncoated surface
additionally bonded to a foil-type, settu-permCable climattc membrane made of
polytetrafluorethylen
using an adhesive. The climatic membrane is water resistant but permrabie to
water steam. When used
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MAY-24-00 04:19Ptv1 FROM-STIKEMAN, ELLIOTT +6132308877 T-698 P.24/27 F-325
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as liner material for hygietx garments, the water vapor ernittrd by the user
can be taken up by the fiber
fabric and then dissipated by the climatic membrane. At the same time, the
fiber layer is protected from
moisture.
Example 3
A non-woven web 100 is combined with a polytetrafluorethylen foil with a
thicltness of 20 m, which is
coated on one side with an adhesive free of solvents. The calender rolls 6.1,
6.2 create a composite. At
its uncoated side, an additional polyethylene foil is placed on the composite
before it enters the calender
rollers 9_1, 9.2. The needle rollers (not shown) apply a perforation to the
second polyethylene foil. The
foil particles intilirating the fiber web during the perforation procedure
cause a mechanical anchoring
between the fiber web with a first foil glued to it and the second foil. The
result is a mat,erial 200 thai is
absorbent towards one surface and tight to liquid towards the other surface,
which is particularly suited
for use in hygiene products_
In recycling, the soiled fiber web can be cotnposied aftrr tearing off the top
foil coatings. The composite
material subject to the inveniion is more rnvironmetually fiiendly than, for
example, the cellulose with
polymeric superabsorbers used for disposable dtapers.
CA 02309998 2000-05-15
